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58 A Quantitative Approach to Evaluating International Environmental Regimes Ronald B. Mi tch ell A Quantitative Approach to Evaluating International Environmental Regimes · Ronald B. Mitchell* Introduction To date, quantitative analysis has been largely absent from efforts to study the effects of international environmental regimes. 1 Yet, applying statistical proce- dures to relatively large sets of quanti ed data offers rich opportunities to address questions central to this research program. Quantitative analysis allows us to answer questions that either cannot be or usually are not answered by other methodologies as well as to reexamine (and buttress or refute) answers to questions already addressed by other methodologies. Quantitative techniques that use careful modeling and appropriate data could shed light on which features of a regime are responsible for a regime’s success and which are super uous, whether the effectiveness of a particular type of regime is problem- contingent, and how a regime’s effectiveness varies with international and domestic contexts. Thus, quantitative analysis offers a valuable complement to qualitative techniques in evaluating the determinants of regime effects and effectiveness. Consider some questions regarding regime effectiveness. Are sanctions always more effective at inducing behavioral change than rewards and, if not, under what conditions are rewards more effective? 2 Are pollution problems, on Global Environmental Politics 2:4, November 2002 © 2002 by the Massachusetts Institute of Technology * A revised version of this article will appear in Arild Underdal and Oran Young, Regime Conse- quences: Methodological Challenges and Research Strategies, Kluwer Academic Publishers, 2003. This article has benefited greatly from comments from Arild Underdal, Oran Young, Detlef Sprinz, and participants in a conference on “Regime Consequences: Methodological Challenges and Research Strategies” hosted by the Centre for Advanced Study of the Norwegian Academy of Science and Letters in June 2000. This article was completed with the generous support of a Summer Research Award from the University of Oregon 1. For some exceptions, see Meyer et al. 1997; and Downs, Rocke, and Barsoom 1998. Several scholars have put together data sets that code a variety of parameters for a range of environmen- tal treaty regimes. The International Regimes Database (IRD) has begun pulling together an ex- tensive set of data on thirty different treaties which, once completed, will constitute a signi cant advance in the data that will be available to the policy and scholarly community. Haas and Sundgren examined trends in environmental treaty making (Haas and Sundgren 1993). Dmitris Stevis has collected data on membership and characteristics of international environ- mental institutions (Stevis 1999). 2. Downs et al. 1996.

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58

A Quantitative Approach to Evaluating International Environmental RegimesRonald B Mi tchell

A Quantitative Approach to EvaluatingInternational Environmental Regimes

middot

Ronald B Mitchell

Introduction

To date quantitative analysis has been largely absent from efforts to study theeffects of international environmental regimes1 Yet applying statistical proce-dures to relatively large sets of quantied data offers rich opportunities toaddress questions central to this research program Quantitative analysis allowsus to answer questions that either cannot be or usually are not answered byother methodologies as well as to reexamine (and buttress or refute) answers toquestions already addressed by other methodologies Quantitative techniquesthat use careful modeling and appropriate data could shed light on whichfeatures of a regime are responsible for a regimersquos success and which aresuperuous whether the effectiveness of a particular type of regime is problem-contingent and how a regimersquos effectiveness varies with international anddomestic contexts Thus quantitative analysis offers a valuable complementto qualitative techniques in evaluating the determinants of regime effects andeffectiveness

Consider some questions regarding regime effectiveness Are sanctionsalways more effective at inducing behavioral change than rewards and if notunder what conditions are rewards more effective2 Are pollution problems on

Global Environmental Politics 24 November 2002copy 2002 by the Massachusetts Institute of Technology

A revised version of this article will appear in Arild Underdal and Oran Young Regime Conse-quences Methodological Challenges and Research Strategies Kluwer Academic Publishers 2003This article has benefited greatly from comments from Arild Underdal Oran Young DetlefSprinz and participants in a conference on ldquoRegime Consequences Methodological Challengesand Research Strategiesrdquo hosted by the Centre for Advanced Study of the Norwegian Academy ofScience and Letters in June 2000 This article was completed with the generous support of aSummer Research Award from the University of Oregon

1 For some exceptions see Meyer et al 1997 and Downs Rocke and Barsoom 1998 Severalscholars have put together data sets that code a variety of parameters for a range of environmen-tal treaty regimes The International Regimes Database (IRD) has begun pulling together an ex-tensive set of data on thirty different treaties which once completed will constitute a signicantadvance in the data that will be available to the policy and scholarly community Haas andSundgren examined trends in environmental treaty making (Haas and Sundgren 1993)Dmitris Stevis has collected data on membership and characteristics of international environ-mental institutions (Stevis 1999)

2 Downs et al 1996

average more difcult or easier to resolve than wildlife preservation problemsDo demands for new behaviors generally work better or worse than banson existing behavior3 Such questions are difcult to answer convincingly withcase studies of single regimes simply because most regimes do not employ bothsanctions and rewards address both pollution and wildlife problems or bothban some behaviors and require others We certainly want to analyze thosevaluable but rare regimes that exhibit variation on such variables since theyconvincingly control many other variables Yet existing case studies of environ-mental regime effectiveness as well as future ones face inherent problems ofgeneralizability Even commendable recent efforts to draw conclusions acrossmultiple regimes each analyzed by a different scholar face difculties in ensur-ing convincing comparability across regimes4 Carefully designed case studiesoften generate compelling ndings that t the case studied quite well but usu-ally do so by sacricing the ability to map those ndings convincingly to manyif any other cases5

Quantitative analysis involves an opposite trade-off Quantitative analysiscan identify general propositions that hold reasonably well across a range ofcases even as they fail to explain any particular case well6 Examining manyregimes and their consequences can help identify what ldquotends to happenrdquo in re-gimes in general and in regimes of particular types It can tell us whether re-gimes generally have large effects on behavior or none at all It can help ldquoll inthe blanksrdquo left by qualitative analysis using patterns across regimes to clarifywhy certain types of regimes address certain types of problems better than oth-ers or why regimes in one issue area work better than otherwise-similar regimesin a different issue area Such comparisons across regimes move us beyond casestudy insights that a particular type of regime can produce a desired outcome tothe often more useful claim that such a design is likely to produce such an out-come in some other context They help us move from statements of possibilityto statements of probability Large-N cross-treaty comparisons can help usdevelop claims from qualitative research for example rening the general claimthat country capacity inuences compliance by evaluating whether the lack of aparticular capacity inhibits compliance with some types of regimes but notother types7 Quantitative techniques offer the promise of replacing claimsthat ldquothis strategy worked in this historical caserdquo with more convincing policy-relevant and contingent prescriptions of which strategy is likely to work best toaddress a given problem under given conditions Although a variety of quantita-

Ronald B Mitchell middot 59

3 Princen 19964 Brown Weiss and Jacobson collected extensive information on compliance and its determi-

nants for ten countries and ve different treaties (Brown Weiss and Jacobson 1998) Miles andUnderdal have developed a database of 44 cases involving regime phases or components (Mileset al 2001)

5 Mitchell and Bernauer 19986 Thus the convincing if contested quantitative nding that democratic states rarely go to war

against each other proves unsatisfactory in explaining why any particular war occurs7 Haas et al 1993 Brown Weiss and Jacobson 1998 and Victor et al 1998

tive techniques could be used to investigate regime consequences in this articleI delineate one quantitative approach that of using regression analysis on paneldata8

De nitions

Recent work on qualitative methodology in general and counterfactuals in par-ticular reminds us that any attempt to make causal claims requires comparing atleast two cases9 Here I clarify some terms useful for discussing quantitativestudy design generally avoiding the term ldquocaserdquo because of its multiple oftenwidely divergent meanings10 Units of analysis are the entities or phenomenaabout which the researcher collects data11 Units of analysis often called casesare a sample from a population or class of all conceptually-similar units thatcould have been studied Variables are the dimensions characteristics or param-eters of these units of analysis with any variable having at least two possible val-ues Quantitative studies seek to evaluate the relationships among the valuesof variables Dependent variables (DVs) are those whose variation we seek toexplain Explanatory or independent variables (IVs) are those whose variationwe look to as possible explanations of the variation in the DV based on theoret-ical claims regarding their causal inuence on that DV Control variables (CVs)are IVs believed to inuence the DV that are included in an analysis in order toseparate their inuence on the DV from that of the primary IV of interest Toavoid confusion I distinguish between a unit of analysis and an observation Anobservation is one set (or vector) of the observed values of all variables (IVs CVsand DV) for a given unit of analysis Notice that this denition allows us tospeak of multiple observations of a single unit of analysis as when we observe aregime (the unit of analysis) at several points in time In a spreadsheet analogyeach column corresponds to a different IV CV or DV each row corresponds to asingle observation the rst column would contain a name for each observationthe dataset could contain rows of multiple observations from each unit of anal-ysis as well as observations from multiple units of analysis and each cell wouldcontain the value of a given variable for a given observation A quantitativestudy of regime consequences requires dening some potential consequent ofregimes as a dependent variable the presence or absence of a regime or some re-gime characteristic as the independent variable of interest and some set of otherfactors predicted to affect the dependent variable as control variables The ana-lyst would then seek out regimes (units of analysis) that allow relatively compa-rable observations across these IVs CVs and DVs

These denitions suggest that research studies are most usefully distin-guished by the number of units of analysis rather than the number of observa-

60 middot A Quantitative Approach to Evaluating International Environmental Regimes

8 The application of this approach is currently underway and will be reported in future work9 King et al 1994 Fearon 1991 and Biersteker 1993

10 See for example Ragin and Becker 1992 Galtung 1967 King et al 1994 and Yin 199411 King et al 1994 52

tions The major virtues and limitations of qualitative ldquocase studyrdquo researchstem from a reliance on one or a relatively few units of analysis even when mul-tiple observations are made Making multiple observations of the same unit ofanalysis holds many variables constant but poses obstacles to the analystrsquos abil-ity to generalize to units of analysis with different values for those variables Themajor virtues and limitations of quantitative research stem from a reliance onmany different units of analysis whether or not there are many or few observa-tions of each Including multiple units of analysis in a study introduces consid-erable variation in variables we would prefer to hold constant thereby posingobstacles to the analystrsquos ability to identify causal relationships that may existIn short qualitative studies must overcome serious obstacles to the external va-lidity of their claims whereas quantitative studies must overcome serious obsta-cles to the internal validity of their claims

Finally although recognizing the value of a broader denition I useregime here to refer to the governance structures surrounding internationalconventions and treaties including the norms rules principles and decision-making procedures as well as the numerous actors who bring those componentsto life12 I use the term ldquosubregimerdquo to refer to different rules compliance strate-gies or other features that provide the basis for making analytically useful dis-tinctions among various components of a regime For example we can view thestratospheric ozone regime based on the Vienna Convention the Montreal Pro-tocol and subsequent amendments as consisting of three subregimes one re-lated to the ozone depleting substances (ODSs) phaseout commitments of de-veloped states one related to the ODS phaseout commitments of thedeveloping states and one related to the commitments of developed states tonance the ODS phaseout of the developing states

The Contributions and Limitations of Quantitative Analysis

Case-studies have provided considerable evidence that certain regimes haveinuenced behavior Indeed a fairly extensive list now exists of regimes deemedeffective or ineffective by thoughtful well-informed scholars13 A quantitativeapproach however allows us to answer more comparative questions that arecentral to the regime consequences research program but that have as yet goneunanswered What types of regimes are most effective Why does one regime in-duce signicantly more behavior change than another apparently comparableregime How do contextual factors condition the effectiveness of a particulartype of regime or subregime It is precisely such questions which involve com-paring across regimes and subregimes that quantitative analysis is particularlywell-suited to address

Ronald B Mitchell middot 61

12 Krasner 198313 Haas et al 1993 Brown Weiss and Jacobson 1998 Victor et al 1998 Young 1997 Young

1999a and Miles et al 2001

Quantitative Modeling to Evaluate a Single Regimersquos Effects

Although ultimately interested in using quantitative analysis to investigate suchcross-regime questions for expository purposes I start by examining how wecould use quantitative analysis to evaluate a single regimersquos effects Consider thequestion of whether the European Convention on Long-Range TransboundaryAir Pollutionrsquos (LRTAP) Sulfur Protocol was effective at altering the sulfur diox-ide (SOx) emissions that contribute to acid precipitation14 Although variousapproaches could be taken to this problem one approach would involve identi-fying an econometric model that examines how SOx emissions (the DV) covarywith membership in the convention (the IV) Several years of SOx emission datafor various countries could be regressed on corresponding data of when if everthose countries ratied the Sulfur Protocol

How we specify the model depends on what we seek to accomplish Al-though we might want to accurately estimate the variation in emissions in thepresent context I assume the analytic goal is to accurately estimate the effect ofregime membership on emissions Given that we need only include those vari-ables on the right hand side of the equation that correlate with both member-ship and emissions Failing to do so would violate the assumptions underlyingregression analysis and lead to misestimating the effect of regime membershipIn the current context we want to include other inuences on sulfur emissionssuch as population coal usage and energy efciency to avoid introducing omit-ted variable bias into our estimates of the inuence of membership Thus wecould specify a model as follows

EMISS 1MEMBER 2POPN 3COAL 4 EFFIC NOTHER

where EMISS is annual emissions of sulfur dioxide MEMBER is coded as 0 inyears of nonmembership and 1 in years of membership and POPN COAL andEFFIC are annual data for population coal usage and energy efciency withOTHER allowing the inclusion of other inuences on sulfur emissions as well

What would the results from such a model or similar models for other re-gimes tell us 1 represents the difference in average emissions that (if we havemodeled emissions correctly) can be attributed to membership a number wewould predict to be negative on the assumption that membership leads statesto reduce their emissions The t-statistic on 1 indicates the likelihood that thisdifference in average emissions would have occurred by chance Although goodqualitative analysis also assesses the likelihood that the observed outcomecould have occurred by chance quantitative analysis encourages prior establish-ment of a criterion (by convention a probability of 5) of whether to interpretan observed covariation of an IV with the DV as random or as resulting from asystematic and presumably causal effect of the IV on the DV15 For IVs that have

62 middot A Quantitative Approach to Evaluating International Environmental Regimes

14 Levy 1993 Levy 1995 and Sprinz 199815 The criteria usually viewed as necessary to infer a causal relationship between A and B are dem-

onstrating ldquorelationshiprdquo (co-variation of the values of A with the values of B) ldquotime prece-

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

average more difcult or easier to resolve than wildlife preservation problemsDo demands for new behaviors generally work better or worse than banson existing behavior3 Such questions are difcult to answer convincingly withcase studies of single regimes simply because most regimes do not employ bothsanctions and rewards address both pollution and wildlife problems or bothban some behaviors and require others We certainly want to analyze thosevaluable but rare regimes that exhibit variation on such variables since theyconvincingly control many other variables Yet existing case studies of environ-mental regime effectiveness as well as future ones face inherent problems ofgeneralizability Even commendable recent efforts to draw conclusions acrossmultiple regimes each analyzed by a different scholar face difculties in ensur-ing convincing comparability across regimes4 Carefully designed case studiesoften generate compelling ndings that t the case studied quite well but usu-ally do so by sacricing the ability to map those ndings convincingly to manyif any other cases5

Quantitative analysis involves an opposite trade-off Quantitative analysiscan identify general propositions that hold reasonably well across a range ofcases even as they fail to explain any particular case well6 Examining manyregimes and their consequences can help identify what ldquotends to happenrdquo in re-gimes in general and in regimes of particular types It can tell us whether re-gimes generally have large effects on behavior or none at all It can help ldquoll inthe blanksrdquo left by qualitative analysis using patterns across regimes to clarifywhy certain types of regimes address certain types of problems better than oth-ers or why regimes in one issue area work better than otherwise-similar regimesin a different issue area Such comparisons across regimes move us beyond casestudy insights that a particular type of regime can produce a desired outcome tothe often more useful claim that such a design is likely to produce such an out-come in some other context They help us move from statements of possibilityto statements of probability Large-N cross-treaty comparisons can help usdevelop claims from qualitative research for example rening the general claimthat country capacity inuences compliance by evaluating whether the lack of aparticular capacity inhibits compliance with some types of regimes but notother types7 Quantitative techniques offer the promise of replacing claimsthat ldquothis strategy worked in this historical caserdquo with more convincing policy-relevant and contingent prescriptions of which strategy is likely to work best toaddress a given problem under given conditions Although a variety of quantita-

Ronald B Mitchell middot 59

3 Princen 19964 Brown Weiss and Jacobson collected extensive information on compliance and its determi-

nants for ten countries and ve different treaties (Brown Weiss and Jacobson 1998) Miles andUnderdal have developed a database of 44 cases involving regime phases or components (Mileset al 2001)

5 Mitchell and Bernauer 19986 Thus the convincing if contested quantitative nding that democratic states rarely go to war

against each other proves unsatisfactory in explaining why any particular war occurs7 Haas et al 1993 Brown Weiss and Jacobson 1998 and Victor et al 1998

tive techniques could be used to investigate regime consequences in this articleI delineate one quantitative approach that of using regression analysis on paneldata8

De nitions

Recent work on qualitative methodology in general and counterfactuals in par-ticular reminds us that any attempt to make causal claims requires comparing atleast two cases9 Here I clarify some terms useful for discussing quantitativestudy design generally avoiding the term ldquocaserdquo because of its multiple oftenwidely divergent meanings10 Units of analysis are the entities or phenomenaabout which the researcher collects data11 Units of analysis often called casesare a sample from a population or class of all conceptually-similar units thatcould have been studied Variables are the dimensions characteristics or param-eters of these units of analysis with any variable having at least two possible val-ues Quantitative studies seek to evaluate the relationships among the valuesof variables Dependent variables (DVs) are those whose variation we seek toexplain Explanatory or independent variables (IVs) are those whose variationwe look to as possible explanations of the variation in the DV based on theoret-ical claims regarding their causal inuence on that DV Control variables (CVs)are IVs believed to inuence the DV that are included in an analysis in order toseparate their inuence on the DV from that of the primary IV of interest Toavoid confusion I distinguish between a unit of analysis and an observation Anobservation is one set (or vector) of the observed values of all variables (IVs CVsand DV) for a given unit of analysis Notice that this denition allows us tospeak of multiple observations of a single unit of analysis as when we observe aregime (the unit of analysis) at several points in time In a spreadsheet analogyeach column corresponds to a different IV CV or DV each row corresponds to asingle observation the rst column would contain a name for each observationthe dataset could contain rows of multiple observations from each unit of anal-ysis as well as observations from multiple units of analysis and each cell wouldcontain the value of a given variable for a given observation A quantitativestudy of regime consequences requires dening some potential consequent ofregimes as a dependent variable the presence or absence of a regime or some re-gime characteristic as the independent variable of interest and some set of otherfactors predicted to affect the dependent variable as control variables The ana-lyst would then seek out regimes (units of analysis) that allow relatively compa-rable observations across these IVs CVs and DVs

These denitions suggest that research studies are most usefully distin-guished by the number of units of analysis rather than the number of observa-

60 middot A Quantitative Approach to Evaluating International Environmental Regimes

8 The application of this approach is currently underway and will be reported in future work9 King et al 1994 Fearon 1991 and Biersteker 1993

10 See for example Ragin and Becker 1992 Galtung 1967 King et al 1994 and Yin 199411 King et al 1994 52

tions The major virtues and limitations of qualitative ldquocase studyrdquo researchstem from a reliance on one or a relatively few units of analysis even when mul-tiple observations are made Making multiple observations of the same unit ofanalysis holds many variables constant but poses obstacles to the analystrsquos abil-ity to generalize to units of analysis with different values for those variables Themajor virtues and limitations of quantitative research stem from a reliance onmany different units of analysis whether or not there are many or few observa-tions of each Including multiple units of analysis in a study introduces consid-erable variation in variables we would prefer to hold constant thereby posingobstacles to the analystrsquos ability to identify causal relationships that may existIn short qualitative studies must overcome serious obstacles to the external va-lidity of their claims whereas quantitative studies must overcome serious obsta-cles to the internal validity of their claims

Finally although recognizing the value of a broader denition I useregime here to refer to the governance structures surrounding internationalconventions and treaties including the norms rules principles and decision-making procedures as well as the numerous actors who bring those componentsto life12 I use the term ldquosubregimerdquo to refer to different rules compliance strate-gies or other features that provide the basis for making analytically useful dis-tinctions among various components of a regime For example we can view thestratospheric ozone regime based on the Vienna Convention the Montreal Pro-tocol and subsequent amendments as consisting of three subregimes one re-lated to the ozone depleting substances (ODSs) phaseout commitments of de-veloped states one related to the ODS phaseout commitments of thedeveloping states and one related to the commitments of developed states tonance the ODS phaseout of the developing states

The Contributions and Limitations of Quantitative Analysis

Case-studies have provided considerable evidence that certain regimes haveinuenced behavior Indeed a fairly extensive list now exists of regimes deemedeffective or ineffective by thoughtful well-informed scholars13 A quantitativeapproach however allows us to answer more comparative questions that arecentral to the regime consequences research program but that have as yet goneunanswered What types of regimes are most effective Why does one regime in-duce signicantly more behavior change than another apparently comparableregime How do contextual factors condition the effectiveness of a particulartype of regime or subregime It is precisely such questions which involve com-paring across regimes and subregimes that quantitative analysis is particularlywell-suited to address

Ronald B Mitchell middot 61

12 Krasner 198313 Haas et al 1993 Brown Weiss and Jacobson 1998 Victor et al 1998 Young 1997 Young

1999a and Miles et al 2001

Quantitative Modeling to Evaluate a Single Regimersquos Effects

Although ultimately interested in using quantitative analysis to investigate suchcross-regime questions for expository purposes I start by examining how wecould use quantitative analysis to evaluate a single regimersquos effects Consider thequestion of whether the European Convention on Long-Range TransboundaryAir Pollutionrsquos (LRTAP) Sulfur Protocol was effective at altering the sulfur diox-ide (SOx) emissions that contribute to acid precipitation14 Although variousapproaches could be taken to this problem one approach would involve identi-fying an econometric model that examines how SOx emissions (the DV) covarywith membership in the convention (the IV) Several years of SOx emission datafor various countries could be regressed on corresponding data of when if everthose countries ratied the Sulfur Protocol

How we specify the model depends on what we seek to accomplish Al-though we might want to accurately estimate the variation in emissions in thepresent context I assume the analytic goal is to accurately estimate the effect ofregime membership on emissions Given that we need only include those vari-ables on the right hand side of the equation that correlate with both member-ship and emissions Failing to do so would violate the assumptions underlyingregression analysis and lead to misestimating the effect of regime membershipIn the current context we want to include other inuences on sulfur emissionssuch as population coal usage and energy efciency to avoid introducing omit-ted variable bias into our estimates of the inuence of membership Thus wecould specify a model as follows

EMISS 1MEMBER 2POPN 3COAL 4 EFFIC NOTHER

where EMISS is annual emissions of sulfur dioxide MEMBER is coded as 0 inyears of nonmembership and 1 in years of membership and POPN COAL andEFFIC are annual data for population coal usage and energy efciency withOTHER allowing the inclusion of other inuences on sulfur emissions as well

What would the results from such a model or similar models for other re-gimes tell us 1 represents the difference in average emissions that (if we havemodeled emissions correctly) can be attributed to membership a number wewould predict to be negative on the assumption that membership leads statesto reduce their emissions The t-statistic on 1 indicates the likelihood that thisdifference in average emissions would have occurred by chance Although goodqualitative analysis also assesses the likelihood that the observed outcomecould have occurred by chance quantitative analysis encourages prior establish-ment of a criterion (by convention a probability of 5) of whether to interpretan observed covariation of an IV with the DV as random or as resulting from asystematic and presumably causal effect of the IV on the DV15 For IVs that have

62 middot A Quantitative Approach to Evaluating International Environmental Regimes

14 Levy 1993 Levy 1995 and Sprinz 199815 The criteria usually viewed as necessary to infer a causal relationship between A and B are dem-

onstrating ldquorelationshiprdquo (co-variation of the values of A with the values of B) ldquotime prece-

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

tive techniques could be used to investigate regime consequences in this articleI delineate one quantitative approach that of using regression analysis on paneldata8

De nitions

Recent work on qualitative methodology in general and counterfactuals in par-ticular reminds us that any attempt to make causal claims requires comparing atleast two cases9 Here I clarify some terms useful for discussing quantitativestudy design generally avoiding the term ldquocaserdquo because of its multiple oftenwidely divergent meanings10 Units of analysis are the entities or phenomenaabout which the researcher collects data11 Units of analysis often called casesare a sample from a population or class of all conceptually-similar units thatcould have been studied Variables are the dimensions characteristics or param-eters of these units of analysis with any variable having at least two possible val-ues Quantitative studies seek to evaluate the relationships among the valuesof variables Dependent variables (DVs) are those whose variation we seek toexplain Explanatory or independent variables (IVs) are those whose variationwe look to as possible explanations of the variation in the DV based on theoret-ical claims regarding their causal inuence on that DV Control variables (CVs)are IVs believed to inuence the DV that are included in an analysis in order toseparate their inuence on the DV from that of the primary IV of interest Toavoid confusion I distinguish between a unit of analysis and an observation Anobservation is one set (or vector) of the observed values of all variables (IVs CVsand DV) for a given unit of analysis Notice that this denition allows us tospeak of multiple observations of a single unit of analysis as when we observe aregime (the unit of analysis) at several points in time In a spreadsheet analogyeach column corresponds to a different IV CV or DV each row corresponds to asingle observation the rst column would contain a name for each observationthe dataset could contain rows of multiple observations from each unit of anal-ysis as well as observations from multiple units of analysis and each cell wouldcontain the value of a given variable for a given observation A quantitativestudy of regime consequences requires dening some potential consequent ofregimes as a dependent variable the presence or absence of a regime or some re-gime characteristic as the independent variable of interest and some set of otherfactors predicted to affect the dependent variable as control variables The ana-lyst would then seek out regimes (units of analysis) that allow relatively compa-rable observations across these IVs CVs and DVs

These denitions suggest that research studies are most usefully distin-guished by the number of units of analysis rather than the number of observa-

60 middot A Quantitative Approach to Evaluating International Environmental Regimes

8 The application of this approach is currently underway and will be reported in future work9 King et al 1994 Fearon 1991 and Biersteker 1993

10 See for example Ragin and Becker 1992 Galtung 1967 King et al 1994 and Yin 199411 King et al 1994 52

tions The major virtues and limitations of qualitative ldquocase studyrdquo researchstem from a reliance on one or a relatively few units of analysis even when mul-tiple observations are made Making multiple observations of the same unit ofanalysis holds many variables constant but poses obstacles to the analystrsquos abil-ity to generalize to units of analysis with different values for those variables Themajor virtues and limitations of quantitative research stem from a reliance onmany different units of analysis whether or not there are many or few observa-tions of each Including multiple units of analysis in a study introduces consid-erable variation in variables we would prefer to hold constant thereby posingobstacles to the analystrsquos ability to identify causal relationships that may existIn short qualitative studies must overcome serious obstacles to the external va-lidity of their claims whereas quantitative studies must overcome serious obsta-cles to the internal validity of their claims

Finally although recognizing the value of a broader denition I useregime here to refer to the governance structures surrounding internationalconventions and treaties including the norms rules principles and decision-making procedures as well as the numerous actors who bring those componentsto life12 I use the term ldquosubregimerdquo to refer to different rules compliance strate-gies or other features that provide the basis for making analytically useful dis-tinctions among various components of a regime For example we can view thestratospheric ozone regime based on the Vienna Convention the Montreal Pro-tocol and subsequent amendments as consisting of three subregimes one re-lated to the ozone depleting substances (ODSs) phaseout commitments of de-veloped states one related to the ODS phaseout commitments of thedeveloping states and one related to the commitments of developed states tonance the ODS phaseout of the developing states

The Contributions and Limitations of Quantitative Analysis

Case-studies have provided considerable evidence that certain regimes haveinuenced behavior Indeed a fairly extensive list now exists of regimes deemedeffective or ineffective by thoughtful well-informed scholars13 A quantitativeapproach however allows us to answer more comparative questions that arecentral to the regime consequences research program but that have as yet goneunanswered What types of regimes are most effective Why does one regime in-duce signicantly more behavior change than another apparently comparableregime How do contextual factors condition the effectiveness of a particulartype of regime or subregime It is precisely such questions which involve com-paring across regimes and subregimes that quantitative analysis is particularlywell-suited to address

Ronald B Mitchell middot 61

12 Krasner 198313 Haas et al 1993 Brown Weiss and Jacobson 1998 Victor et al 1998 Young 1997 Young

1999a and Miles et al 2001

Quantitative Modeling to Evaluate a Single Regimersquos Effects

Although ultimately interested in using quantitative analysis to investigate suchcross-regime questions for expository purposes I start by examining how wecould use quantitative analysis to evaluate a single regimersquos effects Consider thequestion of whether the European Convention on Long-Range TransboundaryAir Pollutionrsquos (LRTAP) Sulfur Protocol was effective at altering the sulfur diox-ide (SOx) emissions that contribute to acid precipitation14 Although variousapproaches could be taken to this problem one approach would involve identi-fying an econometric model that examines how SOx emissions (the DV) covarywith membership in the convention (the IV) Several years of SOx emission datafor various countries could be regressed on corresponding data of when if everthose countries ratied the Sulfur Protocol

How we specify the model depends on what we seek to accomplish Al-though we might want to accurately estimate the variation in emissions in thepresent context I assume the analytic goal is to accurately estimate the effect ofregime membership on emissions Given that we need only include those vari-ables on the right hand side of the equation that correlate with both member-ship and emissions Failing to do so would violate the assumptions underlyingregression analysis and lead to misestimating the effect of regime membershipIn the current context we want to include other inuences on sulfur emissionssuch as population coal usage and energy efciency to avoid introducing omit-ted variable bias into our estimates of the inuence of membership Thus wecould specify a model as follows

EMISS 1MEMBER 2POPN 3COAL 4 EFFIC NOTHER

where EMISS is annual emissions of sulfur dioxide MEMBER is coded as 0 inyears of nonmembership and 1 in years of membership and POPN COAL andEFFIC are annual data for population coal usage and energy efciency withOTHER allowing the inclusion of other inuences on sulfur emissions as well

What would the results from such a model or similar models for other re-gimes tell us 1 represents the difference in average emissions that (if we havemodeled emissions correctly) can be attributed to membership a number wewould predict to be negative on the assumption that membership leads statesto reduce their emissions The t-statistic on 1 indicates the likelihood that thisdifference in average emissions would have occurred by chance Although goodqualitative analysis also assesses the likelihood that the observed outcomecould have occurred by chance quantitative analysis encourages prior establish-ment of a criterion (by convention a probability of 5) of whether to interpretan observed covariation of an IV with the DV as random or as resulting from asystematic and presumably causal effect of the IV on the DV15 For IVs that have

62 middot A Quantitative Approach to Evaluating International Environmental Regimes

14 Levy 1993 Levy 1995 and Sprinz 199815 The criteria usually viewed as necessary to infer a causal relationship between A and B are dem-

onstrating ldquorelationshiprdquo (co-variation of the values of A with the values of B) ldquotime prece-

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

tions The major virtues and limitations of qualitative ldquocase studyrdquo researchstem from a reliance on one or a relatively few units of analysis even when mul-tiple observations are made Making multiple observations of the same unit ofanalysis holds many variables constant but poses obstacles to the analystrsquos abil-ity to generalize to units of analysis with different values for those variables Themajor virtues and limitations of quantitative research stem from a reliance onmany different units of analysis whether or not there are many or few observa-tions of each Including multiple units of analysis in a study introduces consid-erable variation in variables we would prefer to hold constant thereby posingobstacles to the analystrsquos ability to identify causal relationships that may existIn short qualitative studies must overcome serious obstacles to the external va-lidity of their claims whereas quantitative studies must overcome serious obsta-cles to the internal validity of their claims

Finally although recognizing the value of a broader denition I useregime here to refer to the governance structures surrounding internationalconventions and treaties including the norms rules principles and decision-making procedures as well as the numerous actors who bring those componentsto life12 I use the term ldquosubregimerdquo to refer to different rules compliance strate-gies or other features that provide the basis for making analytically useful dis-tinctions among various components of a regime For example we can view thestratospheric ozone regime based on the Vienna Convention the Montreal Pro-tocol and subsequent amendments as consisting of three subregimes one re-lated to the ozone depleting substances (ODSs) phaseout commitments of de-veloped states one related to the ODS phaseout commitments of thedeveloping states and one related to the commitments of developed states tonance the ODS phaseout of the developing states

The Contributions and Limitations of Quantitative Analysis

Case-studies have provided considerable evidence that certain regimes haveinuenced behavior Indeed a fairly extensive list now exists of regimes deemedeffective or ineffective by thoughtful well-informed scholars13 A quantitativeapproach however allows us to answer more comparative questions that arecentral to the regime consequences research program but that have as yet goneunanswered What types of regimes are most effective Why does one regime in-duce signicantly more behavior change than another apparently comparableregime How do contextual factors condition the effectiveness of a particulartype of regime or subregime It is precisely such questions which involve com-paring across regimes and subregimes that quantitative analysis is particularlywell-suited to address

Ronald B Mitchell middot 61

12 Krasner 198313 Haas et al 1993 Brown Weiss and Jacobson 1998 Victor et al 1998 Young 1997 Young

1999a and Miles et al 2001

Quantitative Modeling to Evaluate a Single Regimersquos Effects

Although ultimately interested in using quantitative analysis to investigate suchcross-regime questions for expository purposes I start by examining how wecould use quantitative analysis to evaluate a single regimersquos effects Consider thequestion of whether the European Convention on Long-Range TransboundaryAir Pollutionrsquos (LRTAP) Sulfur Protocol was effective at altering the sulfur diox-ide (SOx) emissions that contribute to acid precipitation14 Although variousapproaches could be taken to this problem one approach would involve identi-fying an econometric model that examines how SOx emissions (the DV) covarywith membership in the convention (the IV) Several years of SOx emission datafor various countries could be regressed on corresponding data of when if everthose countries ratied the Sulfur Protocol

How we specify the model depends on what we seek to accomplish Al-though we might want to accurately estimate the variation in emissions in thepresent context I assume the analytic goal is to accurately estimate the effect ofregime membership on emissions Given that we need only include those vari-ables on the right hand side of the equation that correlate with both member-ship and emissions Failing to do so would violate the assumptions underlyingregression analysis and lead to misestimating the effect of regime membershipIn the current context we want to include other inuences on sulfur emissionssuch as population coal usage and energy efciency to avoid introducing omit-ted variable bias into our estimates of the inuence of membership Thus wecould specify a model as follows

EMISS 1MEMBER 2POPN 3COAL 4 EFFIC NOTHER

where EMISS is annual emissions of sulfur dioxide MEMBER is coded as 0 inyears of nonmembership and 1 in years of membership and POPN COAL andEFFIC are annual data for population coal usage and energy efciency withOTHER allowing the inclusion of other inuences on sulfur emissions as well

What would the results from such a model or similar models for other re-gimes tell us 1 represents the difference in average emissions that (if we havemodeled emissions correctly) can be attributed to membership a number wewould predict to be negative on the assumption that membership leads statesto reduce their emissions The t-statistic on 1 indicates the likelihood that thisdifference in average emissions would have occurred by chance Although goodqualitative analysis also assesses the likelihood that the observed outcomecould have occurred by chance quantitative analysis encourages prior establish-ment of a criterion (by convention a probability of 5) of whether to interpretan observed covariation of an IV with the DV as random or as resulting from asystematic and presumably causal effect of the IV on the DV15 For IVs that have

62 middot A Quantitative Approach to Evaluating International Environmental Regimes

14 Levy 1993 Levy 1995 and Sprinz 199815 The criteria usually viewed as necessary to infer a causal relationship between A and B are dem-

onstrating ldquorelationshiprdquo (co-variation of the values of A with the values of B) ldquotime prece-

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

Quantitative Modeling to Evaluate a Single Regimersquos Effects

Although ultimately interested in using quantitative analysis to investigate suchcross-regime questions for expository purposes I start by examining how wecould use quantitative analysis to evaluate a single regimersquos effects Consider thequestion of whether the European Convention on Long-Range TransboundaryAir Pollutionrsquos (LRTAP) Sulfur Protocol was effective at altering the sulfur diox-ide (SOx) emissions that contribute to acid precipitation14 Although variousapproaches could be taken to this problem one approach would involve identi-fying an econometric model that examines how SOx emissions (the DV) covarywith membership in the convention (the IV) Several years of SOx emission datafor various countries could be regressed on corresponding data of when if everthose countries ratied the Sulfur Protocol

How we specify the model depends on what we seek to accomplish Al-though we might want to accurately estimate the variation in emissions in thepresent context I assume the analytic goal is to accurately estimate the effect ofregime membership on emissions Given that we need only include those vari-ables on the right hand side of the equation that correlate with both member-ship and emissions Failing to do so would violate the assumptions underlyingregression analysis and lead to misestimating the effect of regime membershipIn the current context we want to include other inuences on sulfur emissionssuch as population coal usage and energy efciency to avoid introducing omit-ted variable bias into our estimates of the inuence of membership Thus wecould specify a model as follows

EMISS 1MEMBER 2POPN 3COAL 4 EFFIC NOTHER

where EMISS is annual emissions of sulfur dioxide MEMBER is coded as 0 inyears of nonmembership and 1 in years of membership and POPN COAL andEFFIC are annual data for population coal usage and energy efciency withOTHER allowing the inclusion of other inuences on sulfur emissions as well

What would the results from such a model or similar models for other re-gimes tell us 1 represents the difference in average emissions that (if we havemodeled emissions correctly) can be attributed to membership a number wewould predict to be negative on the assumption that membership leads statesto reduce their emissions The t-statistic on 1 indicates the likelihood that thisdifference in average emissions would have occurred by chance Although goodqualitative analysis also assesses the likelihood that the observed outcomecould have occurred by chance quantitative analysis encourages prior establish-ment of a criterion (by convention a probability of 5) of whether to interpretan observed covariation of an IV with the DV as random or as resulting from asystematic and presumably causal effect of the IV on the DV15 For IVs that have

62 middot A Quantitative Approach to Evaluating International Environmental Regimes

14 Levy 1993 Levy 1995 and Sprinz 199815 The criteria usually viewed as necessary to infer a causal relationship between A and B are dem-

onstrating ldquorelationshiprdquo (co-variation of the values of A with the values of B) ldquotime prece-

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

such ldquostatistically signicantrdquo t-statistics (and for which independent theoreticalsupport exists for making causal claims) the can be interpreted as the averagemagnitude of the ldquoeffectrdquo the IV has on the DV having controlled for all otherIVs16 It is important to distinguish the statistical signicance of the t-statisticfrom the meaningfulness or what we might call policy signicance of that IVThus a study might show that members emitted only slightly less pollutionthan nonmembers but provide convincing support that their lower emissionslevels cannot be readily explained by factors other than their membership in theregime A t-statistic indicates whether the co-variation of IV and DV was ldquorealrdquo(more precisely whether it was likely to have occurred by chance) while theindicates whether the co-variation of the IV and DV was ldquolargerdquo

The coefcient on membership 1 therefore corresponds to thecounterfactuals of qualitative analyses Counterfactual emissions for a memberstate in a given year ie its emissions had it not been a member can be roughlyestimated as its actual emissions for that year minus 117 Using the model inthis way or others to estimate counterfactuals for specic countries could sup-plement qualitative efforts to generate counterfactuals in indices of regimeinuence18 The R2 represents the fraction of all the variation in the DV in thiscase EMISS explained by the variation in all the IVs taken together Thus the R2

provides an estimate of how well the analyst has captured the factors thatinuence the DV or how complete the analystrsquos model of the DV is19

Quantitative Modeling to Compare Regimersquos Effects

With this single regime model as background how do we devise a moregeneralizable model that can use data from several regimes and subregimes toaddress comparative questions such as what features make a regime effectiveAs an example consider the debate over whether treaty ldquoenforcementrdquo involvingsanctioning violation induces behavior change more effectively than ldquomanage-mentrdquo involving facilitating compliance20 Precisely because each of these ap-proaches will be ineffective sometimes this question requires identifying eitherthe ldquoaveragerdquo effect or context-contingent effects of these approaches across arange of regimes Indeed case studies documenting compliance rates with ei-

Ronald B Mitchell middot 63

dencerdquo (changes in A precede changes in B) and ldquononspuriousnessrdquo (the ability to rule outother possible causal variables) (Asher 1976 11 and Kenny 1979 3ndash5)

16 Of course a fully accurate interpretation of the in this way requires that the analyst has paidcareful attention to multi-collinearity heteroskedasticity omitted variable bias and a variety ofadditional statistical concerns

17 A more rened counterfactual might subtract 1 from emissions forecast by the model usingeach statesrsquo actual values for all the IVs The impact of regime membership for that state wouldthen consist of the difference between its actual emissions and the emissions forecast by thismethod

18 Helm and Sprinz 1999 and Sprinz and Helm 199919 The adjusted R2 is conceptually identical but corrects this estimate to reect the fact that adding

more IVs to a regression equation can increase the R2 even if the additional IVs do not have anysignicant correlation with the DV

20 Chayes and Chayes 1995 and Downs et al 1996

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

ther type of approach can contribute to but not resolve the debate since theycannot assure us whether high (or low) rates in one regime constitute a system-atic tendency or a mere anomaly Quantitative analysis is crucial to determinewhether sanctions work better than rewards across a range of regimes and cir-cumstances after controlling for the degree or ldquodepthrdquo of cooperation21 Thisquestion also highlights the value of a subregime-based analysis since many re-gimes use enforcement for some rules and management for others as evident inthe Montreal Protocolrsquos sanctions for developed country noncompliance andassistance for developing country noncompliance

This debate surrounds the hypothesis that member states make major orldquodeeprdquo changes in behavior in response to regimes and subregimes backed bysanctions but not in response to those supported by rewards How might weconstruct a regression model of such a hypothesis Since we want to includedata from different regimes we must have a DV that is comparable across re-gimes Consider the following model

CRB 1MEMBER 2SANCTION 3MEM-SANCT4DEPTH 5CGNP 6CPOP NOTHER

where CRB is some annual measure of Change in Regulated Behavior under var-ious treaties MEMBER is again coded as 1 in years during which a state is amember and 0 otherwise SANCTION is coded as 1 for years in which rules sup-ported by sanctions are in force and 0 otherwise (although any other regime fea-ture could be similarly included) and MEM-SANCT is coded as 1 in years forwhich a sanction-based rule is in effect for a state and 0 otherwise DEPTH issome indicator of the depth of cooperation CGNP is the annual change inGNP CPOP is the annual change in population and OTHER represents a rangeof other factors believed to covary with CRB Assuming that the operational-ization of CRB under various regime rules allows convincing comparison acrossrules (discussed below) and again that omitted determinants of behaviors donot correlate with the included IVs such a regression could provide us with con-siderable information on the extent and pathways by which regimes inuencebehavior The value of 1 and its t-statistic would document how much mem-bership tends to inuence behavior holding ldquotyperdquo of treaty (dened as sanc-tions or not) constant The coefcient of SANCTION 2 would appear to repre-sent an estimate of the inuence of sanctions on state behavior And it doesBut it constitutes an estimate of the average change in regulated behaviors ofboth members and nonmembers of regimes that employ sanctions compared tothose that do not ie how all states in the sample (whether members or not)differ with respect to behaviors regulated by sanction-based regimes and behav-iors regulated by other types of regimes22 Thus 2 tests the inuence of sanc-

64 middot A Quantitative Approach to Evaluating International Environmental Regimes

21 Downs et al 199622 2 represents the change in behavior that correlates with variation in whether a regime has

sanctions or not controlling for membership (ie comparing members of sanction-based re-gimes to members of other regimes and nonmembers of sanction-based regimes to nonmem-bers of other regimes)

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

tions in a theoretical model in which all states (whether members or not) re-spond to regimes being introduced into the international system anassumption that seems likely to underestimate the inuence of sanctions by in-cluding the behavior of nonmembers in the estimate Regimes can of courseinuence nonmember behavior as evident in the non-proliferation regimes im-pact on the nuclear programs of states that are not party to it

Yet we have strong theoretical reasons to believe that sanctions have moreif not exclusive inuence on member states than on nonmembers a view cap-tured in the interaction term MEM-SANCT The coefcient on MEM-SANCT 3represents the additional change in behavior (CRB) induced among membersof sanction-based regimes or subregimes In this model 1 estimates theinuence of becoming a member of a non-sanction regime and 1 3 esti-mates the inuence of becoming a member of a sanction regime Although asomewhat complex model simply constructing the model forces us to clarifyunderlying notions of how regimes may inuence state behavior Indeed themodel allows us to assess whether regimes wield inuence over all states in thesystem (whether members or not) only over states that are members or onlyover members if they employ sanctions23

Our faith in these estimates especially in whether to interpret them as theldquoinuencerdquo of a regime rather than mere correlation depends on excludingother possible explanations of behavior change Most importantly the modelmust include (and thereby remove the variation in behavior that correlateswith) ldquodepthrdquo ie how much was required of members since it is central to theclaims made in the enforcement-management debate24 We also want to includeother inuences on environmentally-harmful behaviors such as the level ofeconomic activity population and other factors The most important benet ofincluding such indicators lies in increasing our condence that our estimates ofthe inuence of membership and sanctions (ie 1 2 and 3) more accuratelyreect their real correlation with CRB rather than a spurious correlation drivenby left out or omitted variables However the coefcients on these variables mayprove of interest in their own right Thus 4 represents the change in regulatedbehaviors induced by a 1 change in depth of cooperation (although we mightalso want to include a membership-depth interaction term) 5 that induced bya 1 change in economic growth and 6 that induced by a 1 change in popu-lation

Although illustrated in terms of evaluating the inuence of sanctionswhile controlling for depth of cooperation the foregoing discussion demon-strates a generic model useful for evaluating the inuence of any regime featurewhile controlling for other features or to evaluate the inuence of contextualvariables on regime effectiveness Answering any specic question requiresspecic theoretically-informed modeling that captures relevant variables of in-

Ronald B Mitchell middot 65

23 1 represents the additional change in behavior induced in members of a regime controllingfor type of regime (ie comparing members of sanction-based regimes to nonmembers ofthose regimes and members of non-sanction-based regimes to nonmembers of those regimes)

24 Downs et al 1996

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

terest interactions among variables and appropriate control variables But themodel delineated shows how such inuences can be modeled

Before proceeding some caveats and limitations of quantitative analysisdeserve mention First as already noted quantitative analysis trades off accu-racy for generalizability Including more units of analysis and more observa-tions means doing so with less knowledge and detail We rightly place morecondence in a researcherrsquos assessment of the Atlantic tuna regimersquos effects ifshe studied only that regime than if she studied it as one of ten sheries re-gimes However we also rightly are more cautious in generalizing from an ex-planation of regime success derived solely from the Atlantic tuna regime thanfrom one derived from a large set of regimes Second because quantitative anal-ysis requires simplifying each observation to collect data on many observationsit depicts trends in inuence across regimes better than stories of a particular re-gimersquos inuence on a particular state Thus the single-regime LRTAP modelabove would be more useful at identifying the average emission reductions in-duced by LRTAP membership than which countriesrsquo behaviors were mostinuenced by LRTAP25 Claims from quantitative analyses even if convincingmay be too probabilistic or vague for the desired purposes Third systematicand careful specication of variables and models can capture the presence or ab-sence strength or quality of even quite subjective assessments of institutionaland contextual features But the quantitative analyst must choose between cap-turing empirical richness by including and coding variables for a myriad of dis-tinguishing features or using coarser coding schemes with correspondingsimplication Such simplifying of complex phenomena by denition ignoresnuance and makes accurate mapping of ndings to a given regime (internal va-lidity) less compelling than their mapping to a large set of regimes (externalvalidity)

Choosing Sample Size and the Unit of Analysis

Before describing how to quantitatively analyze regime effects and effectivenesswe must ask whether such an analysis is possible Quantitative analysis requiresthat the analyst have multiple and comparable observations Most statisticaltechniques require at least as many observations (remember the denitionsabove) as independent and control variables Many more observations areneeded to distinguish real effects from random covariation of the IV and DVwith at least 5 (and preferably 20) times as many observations as IVs usually rec-ommended26 Even higher ratios are recommended when the IV of interest is ex-pected to have only a small effect on the DV or if the measurement of variablesis imprecise two problems that seem particularly likely in the study of re-gimes27 If we assume that producing a reasonable regression model of any DV

66 middot A Quantitative Approach to Evaluating International Environmental Regimes

25 Levy 199326 Tabachnick and Fidell 1989 12927 Tabachnick and Fidell 1989 129

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

of interest involves 5 to 10 IVs this suggests that we need data sets of at least 50and preferably a few hundred observations including observations from a rangeof different units of analysis28

This simple calculation seems to conrm the common assumption thatquantitative analysis is not possible because there are too few environmental re-gimes to compare Recalling the denition above if each unit of analysis corre-sponds to a regime or its absence than we certainly have too few to run a regres-sion Of the several hundred extant multilateral environmental treaties mosthave little reliable data on any conceivable dependent variable and fewer stillhave the needed comparative data for the period prior to regime formation In-deed reliable data collection often only starts upon regime formation Theseproblems preclude using quantitative analysis to assess regime consequences ifwe consider regimes as our unit of analysis However quantitative analysis canbecome possible and appropriate if we increase the number of observations byone of three methods each already alluded to examining ldquosubregimesrdquo ratherthan regimes observing multiple years rather than one year before and one yearafter regime formation and observing individual countries rather than all statesas a group

First as noted theoretical considerations recommend viewing regimes ascomposed of distinct sub-units Evaluating the ldquoregulatory effectiveness of re-gimesrdquo seems as valuable as evaluating ldquothe regulatory effectiveness of govern-mentsrdquo Our understanding of domestic governance derives from examiningvariation in regulatory effectiveness within a government as well as betweengovernments Questions like ldquodo governments induce compliance with theirregulationsrdquo or ldquodo citizens comply with lawsrdquo entail such high levels of aggre-gation that they are unlikely to identify particularly compelling relationshipsAssessing whether hiring more police ofcers ldquoreduces trafc violationsrdquo for ex-ample requires either mindlessly aggregating running red lights with exceedingthe speed limit or using one of these metrics in lieu of both Yet it is preciselythe variance in trafc light vs speeding violations that shed light on the condi-tions under which people comply with trafc laws Likewise with regimes Mostregimes contain many proscriptions and prescriptions each of which can beviewed as a distinct subregime It is likely that a regimersquos effectiveness variesacross these rules in ways that reect variations in the rules themselves and inthe strategies used to induce compliance with them So long as each rule has aseparate indicator of its effect there is good reason to treat these as separateunits of analysis Comparing subregimes has the additional virtue of holdingmany variables constant across that subset of observations derived from thesame regime

Ronald B Mitchell middot 67

28 Statistical power analysis conrms these general rules of thumb suggesting that a regressionmodel using 8 independent variables a statistical signicance test (ie a) of 05 and a powercriterion of 80 would need a sample of 107 to detect a ldquomediumrdquo effect size and a sample ofover 700 to detect a ldquosmallrdquo effect size (Cohen 1992 155ndash159)

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

Second even most case studies split regimes into at least two observationsWhatever the dependent variable making a convincing argument requires com-paring observations of member state behavior under the regime to some pre-regime period to their behavior in similar contexts without a regime tocorresponding counterfactual thought experiments or to the behavior of com-parable nonmembers In all of these instances however each regime-year canbe considered to be a separate observation Data on many air land and waterpollutants as well as catch and trade statistics for various species are often avail-able for a range of years that span entry into force of corresponding regimesThere is no reason to simply average data for the ve years before a regime en-ters into force and compare it to the average for ve years thereafter when non-aggregated annual data provides greater analytic leverage29

Third some states never join certain regimes and those that do do so atdifferent times Such variation in membership in regimes and in opting out ofcertain provisions permits comparing the behavior of states for whom an inter-national rule is binding to their own behavior before it became binding as wellas to that of states who are not legally bound Even allowing that regimes mayhave some inuence on states that are not members it seems reasonable to as-sume that effective regimes have different if not greater inuences on membersthan nonmembers When combined with the previous points this suggests thatthe best approach involves dening units of analysis at the subregime level andrecording data on behavior membership GNP and other appropriate variablesfor all relevant countries and years That is each observation would be identi-ed in terms of subregime country and year

Conducting the Empirical Analysis

How then might we actually run an econometric model to assess the inuenceof different regime features A modelrsquos appropriateness depends of course onthe purpose of inquiry But all models require careful attention to dening thedependent variable for study selecting independent variables to capture poten-tial sources and pathways of regime inuence and identifying additional inde-pendent variables that explain variation in the dependent variable and forwhich we want to control The data must be collected so it allows sensible com-parison across regimes and subregimes a particularly difcult problem

A word of note is also in order Underdal and Young have promoted thevalue of distinguishing regime effectiveness from regime effects ie a regimersquosintended and direct effects from other unintended or indirect effects30 Whilerecognizing the value of research on both of these phenomena the followingdiscussion uses the mainstream debate on simple effectiveness dened as a re-gimersquos or subregimersquos success at achieving the goals that led to its creation for

68 middot A Quantitative Approach to Evaluating International Environmental Regimes

29 Murdoch et al 199730 Underdal and Young forthcoming

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

expository purposes There is no reason however why any potential intendedor unintended effect of an environmental regime such as inuences on equityeconomic growth or the growth of other institutions cannot be modeled inparallel ways

Dening the Dependent Variable

Considerable scholarship has sought to dene regime effectiveness Much earlyliterature used compliance as a metric of effectiveness31 Most recent work hasargued for behavior change and environmental progress as more appropriatemetrics32 A new phase of this debate has been opened recently by efforts toidentify a common metric or index for cross-regime comparisons of effects andeffectiveness Helm and Sprinz have proposed dening effectiveness as theamount of progress induced by the regime toward a regimersquos collective opti-mum from the no-regime outcome33 Their strategy requires estimating both theno-regime counterfactual and the collective optimum using game-theory opti-mization or interviews of experts34 Miles and Underdal attack the same prob-lem by using qualitative case studies to assess effectiveness on different scales(ranging from 0 to 4 for behavioral change and 1 to 3 for environmental im-provement) and then normalizing them to a range from 0 to 135

Both approaches produce a common metric of effectiveness ranging fromno improvement relative to the no-regime outcome to full achievement of thecollective optimum Despite the value of these efforts to allow comparison of ef-fectiveness across regimes they cannot serve as dependent variables in a regres-sion model Both scores are essentially qualitative assessments of regime effec-tiveness but effectiveness is precisely what we seek to derive from the regressionequation It might seem tempting to use their effectiveness metrics as the DV ina regression equation But as already noted a regression identies both themagnitude ( ) and likelihood (t-statistic) that the DV covaries systematicallywith some IV representing the presence or absence of some regime feature andestimates the counterfactual as actual performance minus Thus using metricssimilar to those proposed by Helm and Sprinz or Miles and Underdal as a DVwould entail regressing a qualitative assessment of regime effect on some re-gime characteristic to see if the regime had an effect Although this obviouslymakes little sense other research programs have made such errors36 Thus al-

Ronald B Mitchell middot 69

31 Mitchell 1994 Mitchell 1996 Chayes and Chayes 1993 and Brown Weiss and Jacobson 199832 Young 1999a Young 1999b Victor et al 1998 Miles et al 2001 Stokke 1997 and Wettestad

199933 Sprinz and Helm 1999 and Helm and Sprinz 199934 Sprinz and Helm 1999 36535 Underdal 2001 436 Indeed the seminal quantitative work on economic sanctions made precisely this mistake re-

gressing a DV that included ldquothe contribution made by sanctions to a positive outcomerdquo onwhether sanctions were imposed or not to determine whether sanctions inuence state behav-ior (Hufbauer Schott and Elliott 1990)

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

though neither pair of authors has suggested using their metric to quantitativelyanalyze regime effectiveness the temptation for others to do so should beavoided

Although not useful as DVs these metrics highlight the need for somecomparable measure of change in actual performance (whether involving be-havior or environmental quality) as our DV Yet we need to avoid confusing cre-ation of a common metric of effectiveness with creation of a comparable one De-nominating each regimersquos progress toward its collective optimum in similarunits does not allow interpreting those units as reecting meaningful differ-ences across regimes As many authors have noted regimes address problemsthat vary signicantly in their resistance to remedy37 We want to capture bothcomponents of success ie how much change the regime induced and howhard that amount of change was to induce Consider trying to evaluate whetherthe whaling or ozone protection regime was more effective Assume heuristi-cally their goals were recovery of whale stocks to historical levels and completeelimination of ozone depleting substances (ODSs) If we assume that both ODSemissions and whales killed are at least somewhat lower than they would bewithout the regimes then both regimes should be assessed as ldquosomewhatrdquo ef-fective But which was moreso Based on the magnitude of behavior changealone we might assess the ozone regime as quite effective for inducing addi-tional progress toward complete ODS phaseout even after eliminating theinuence of non-regime reasons for phaseout We might view the whaling re-gime as completely unsuccessful since actual performance in terms of whalestocks fell so far short of complete recovery And indeed it may be appropriateto view the whaling regime as far less effective than the ozone regime Howeverthe degree to which the ozone regime ldquobestsrdquo the whaling regime when mea-sured against the collective optimum owes as much to differences in thedifculty of achieving the collective optimum as to differences in the regimersquoseffectiveness at doing so

How then do we devise a DV that can be used to compare convincinglyacross regimes I believe a satisfactory DV requires capturing environmental ef-fort as well as behavior change We need to capture the difculty of makingprogress toward the collective optimum as well as how much progress wasmade Assessing relative effectiveness across regimes as opposed to absolute ef-fectiveness of a regime relative to the counterfactual requires assessing both theamount of change and the per unit effort needed to make such change Let us con-sider these components in turn First we want our measure of behavioral or en-vironmental change to be comparable across analysis units Although all can beexpressed numerically we clearly cannot include numbers of whales killedacres of deforestation and tons of pollutants emitted in a single regressionHow should we address this problem It seems unlikely that we can identify asingle metric that allows convincing comparisons across all regime types Re-

70 middot A Quantitative Approach to Evaluating International Environmental Regimes

37 Miles et al 2001 Young 1999b and Wettestad 1999

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

gime goals simply differ too much However it may be possible to identify a rel-atively few categories of regimes that have sufciently similar goals to allowvalid comparison among regimes within a category Thus one category mightinclude regimes that target pollutant emissions including the European regimeaddressing acid precipitation the Montreal Protocol the Climate Change Con-vention and a variety of river pollution treaties A second category might in-clude wildlife regimes such as those addressing trade in endangered specieswhaling polar bears fur seals and various sheries A third category might in-clude habitat preservation regimes such as the conventions on wetlands worldheritage sites and desertication One can imagine devising a single compara-ble indicator of effectiveness for each category for pollutant regimes levels ofemissions for wildlife regimes numbers of animals killed or changes in speciespopulation and for habitat regimes relevant acreage

Even among regimes whose indicators can be expressed in similar units(for example sulfur dioxide nitrogen oxide volatile organic compoundsODSs and CO2 emissions can all be expressed in tons) differences in the levelsof emissions make a regression using absolute levels (raw data) inappropriateTo compare across regimes or even across countries within a regime requiresnormalizing data One might consider using annual changes in those absolutelevels (rst differences) or an index based on setting a given yearrsquos level as 100Calibrating across regimes across countries and across time however seems torecommend normalizing absolute levels into annual percentage change scores(APCs) Using percentage change makes otherwise disparate data relativelycomparable by adjusting for the initial level of the underlying activities both atthe regime and country levels Calculating those percentage changes on an an-nual basis provides the additional benet of re-calibrating (and thus allowingcomparison across) every year rather than the single normalization of indexingThe differences are shown in Table 1 and 2

The second usually neglected component necessary to a notion of rela-tive effectiveness is per unit effort (PUE) The challenging goal here is to capturethe difculty of inducing a given change in behavior in a way that allows com-parison across regimes countries and time If we accept annual percentagechange (APC) as one part of our DV then it makes sense to dene PUE as thedifculty of achieving a 1 change in the relevant behavior be it emission re-duction animals not killed or acres protected In pollution regimes this corre-sponds to the abatement costs of a 1 emission change in wildlife regimesperhaps to the benets foregone by not killing 1 of a given species or the costsof protecting an additional 1 of the population and in habitat regimes per-haps to the cost of protecting an additional 1 of the existing acreage Such anapproach has the virtue of not producing astronomically high scores at low ab-solute levels of an activity since a 1 change from already low levels of an activ-ity involves a small absolute reduction and therefore will counter the inuenceof the increasing marginal cost of environmental protection We can imaginethree levels of resolution in such gures At the grossest level one can imagine

Ronald B Mitchell middot 71

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

each regime having a single PUE score designed simply to capture variation incosts across regimes At the next level one can imagine PUE scores varying bothby regime and by country38 Finally one can imagine PUE scores varying by re-gime and by country over time

The product of these PUE and APC constructs creates a total effort scorethat has several virtues as a DV Essentially it represents the effort made at envi-ronmental protection in ldquoregime effort unitsrdquo or REUs Regressing REUs on a setof IVs including at least one regime-related variable would allow us to use theon regime-related variables as a metric of regime effectiveness that would becomparable across analytic units Thus a well-specied regression model of en-vironmental effort (in REUs) that produced a signicant t-statistic on a mem-

72 middot A Quantitative Approach to Evaluating International Environmental Regimes

Tables 1 and 2Example of a Dependent Variable Measured in Absolute and Relative Terms

Dependent Variable as Absolute MetricExample SOx and NOx Emissions (000s of tonnes)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 195 176 160 115 102 91 83 63SOx Belgium 400 377 367 354 325 372 334 318SOx Canada 3692 3627 3762 3838 3695 3236 3245 3117SOx Iceland 18 18 16 18 17 24 23 24NOx Austria 220 217 213 203 196 194 198 188NOx Belgium 325 317 338 345 357 339 335 343NOx Canada 2038 2043 2131 2204 2188 2104 2003 1997NOx Iceland 21 22 24 25 25 26 27 28

Dependent Variable as Annual Percentage Change (APC)Example SOx and NOx Emissions ( change from prior year)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 106 97 91 281 113 108 88 242SOx Belgium 200 58 27 35 82 145 102 48SOx Canada 66 18 37 20 37 124 03 39SOx Iceland 53 00 111 125 56 412 42 43NOx Austria 09 14 18 47 34 10 21 51NOx Belgium na 25 66 21 35 50 12 24NOx Canada 89 02 43 34 07 38 48 03NOx Iceland 45 48 91 42 00 40 38 37

38 Indeed the assumption that abatement costs and by implication PUE scores vary by countryunderlies the exibility mechanisms designed into the Climate Change Convention

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

bership variable would allow interpretation of as the change in environmen-tal effort induced by membership

The plausibility of using REUs for comparison across regimes depends ofcourse on how convincingly we assign PUE scores across regimes Using REUsto compare countries within a regime requires only estimating how the costs ofmaking a 1 change on a given environmental problem vary by country Com-paring the effectiveness of two different regimes or the responses of individualcountries across regimes requires determining how the costs of making a 1change on two different environmental problems compare How do we convincinglyassess whether the costs of a 1 change in sulfur emissions are greater or less(both on average and for specic countries) than those of increasing elephant orwhale populations by 1 Though difcult the problem may not be unresolv-able One approach involves limiting comparisons to regimes with relativelysimilar types of costs Thus we may feel condent comparing abatement costsfor sulfur emissions and volatile organic compounds but far less condent com-paring them for sulfur emissions and wetlands protection Initial efforts mayneed to compare similar regimes and address more challenging comparisons af-ter developing experience and methodologies for identifying PUE in differentcontexts Despite these practical difculties in instances where PUEs are avail-able REUs based on them may offer opportunities to make the cross-regimecomparisons we seek

They also help us keep efciency and effectiveness separate Consider a re-gime that induced one state in a given year to reduce its sulfur emissions by 2at a cost of $20 million per 1 reduction (or $40 million total) while anotherstate in that same year reduced its sulfur emissions by 2 at a cost of $5 millionper 1 reduction (or $10 million total) The REU appropriately reects thecommon-sense view that the regime was more effective with the former state (itinduced a more costly change in behavior) but that the latter state was moreefcient in undertaking its commitments

Identifying Independent Variables

Having chosen a dependent variable (whether dened in terms of environmen-tal effort units or some other metric) we need a model of both regime andother potential determinants of variation in that DV The earlier discussionsheds light on three different types of regime inuence that can be modeledmembership features and membership-feature interactions The most obviouselement involves using membership (coded as above) as the primary independ-ent variable of regime inuence with membership varying by country year andsubregime Intuitively this corresponds to (and allows us to evaluate) a theorythat holds that regimes only inuence the behavior of those states legally boundby a given rule Employing a membership variable allows estimating regimeinuence by comparing a countryrsquos behavior while a member to its behaviorwhile a nonmember (eliminating cross-country effects) as well as by comparing

Ronald B Mitchell middot 73

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

member behavior to nonmember behavior during the same time period (elimi-nating cross-time effects) Regimes may also inuence behavior by establishingnorms or other social pressure that inuence nonmembers albeit less so thanmembers This suggests including indicators for different regime features thatvary by subregime and over time but whose values are the same for all countriesregardless of membership Such features could be coded as 1 after the date atreaty was signed (or negotiations began or a provision entered into force) and0 otherwise Regime features also may inuence members differently than non-members This requires including membership-feature interaction terms if weare to assess how regime features inuence members how they inuence non-members and whether the inuence differs across the groups

We also need to identify other IVs as control variables to avoid introducingomitted variable bias Just as we constructed a DV for environmental effort thatwould allow comparison across regimes a model that produces interpretableexplanations of changes in environmental effort must select and dene inde-pendent variables in ways that allow comparison across regimes The IVs wemight employ to maximize our explanation of variance in sulfur emissions (ieto produce a large R2) will tend to prove useless for evaluating volatile organiccompound emissions let alone sh catch data We need a relatively generic andgeneralizable set of IVs with strong explanatory power over a wide range of re-gimes In essence we desire a model that balances explanatory power withgeneralizability sacricing model specicity up to a point at which doing so re-quires ldquotoo bigrdquo a loss in explanatory power

To estimate the extent to which regimes increase the environmental pro-tection efforts of states requires devising a set of ldquousual suspectrdquo IVs such as in-dicators of economic size and level of development state of technologicaldevelopment type of government population land area and level of environ-mental concern Although each of these IVs could be operationalized in differ-ent ways at least for those that vary over time using annual percentage changeswould provide the most useful mechanism for modeling the DV of REU itselfan annual percentage change Thus we would want to use annual percentagechange in GNP rather than raw GNP gures

Developing control variables for such a model may be best thought of as acollective activity among scholars Those investigating ldquoenvironmental Kuznetscurvesrdquo have developed models that predict national pollution levels based onindicators of economic growth population trade inequality technology andother factors39 Given a common and growing database of evidence on differentregimes such a model could be rened by adding regime-related variables to aninitial specication derived from this prior work Existing variables in thespecication could be removed as more accurate proxies were found A collec-tive effort to evaluate critique and improve such a generic model could foster a

74 middot A Quantitative Approach to Evaluating International Environmental Regimes

39 For a review of this literature see Harbaugh et al 2001

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

research program that collectively and progressively produced a more explana-tory and generalizable model

An optimal approach to model specication may involve combining a ge-neric specication of some base set of IVs that could be used in analyzing obser-vations from all regimes more extensive and regime-specic specications foruse in quantitative analyses of subregimes within a single regime and interme-diate models that include IVs that apply to a range but not all regimes rela-tively well A set of intermediate models could be developed for different typesof regimes Thus one might imagine a specication for pollution treaties withvariables for development technology and intensity of resource use Wildlifeprotection treaties might be modeled using demand for the species as exhibitedby price stock recruitment rates and number of countries having access to thespecies Further research could identify more useful distinctions includingmodeling regimes that address say overappropriation separately from thosethat address underprovision problems with indicators of administrative capac-ity playing a central role in the rst and indicators of nancial capacity playing acentral role in the second40

Using Panel Data

Armed with a model of regime inuence and a level of analysis that producesenough data to distinguish the real effects of regimes from random covariationwe must consider the appropriate analytic techniques Dening observations interms of subregime country and year allows use of panel or pooled time-seriesdata Although mathematically complex the analytic techniques used to ana-lyze panel data are conceptually easy to follow Their major advantage lies intheir ability to ldquotake into account unobserved heterogeneity across individualsandor through timerdquo41 Thus panel data can identify the extent to which thedependent variable covaries with the regime-related independent variables aftercontrolling both for differences across countries and for variation over time

Conceptualized visually the values of the DV t in a matrix of rows ofcountry-subregimes columns of years and cells of data as shown in Tables 1and 2 above The values of IVs can be t in corresponding matrices An observa-tion would consist of a single ldquoslicerdquo through these matrices picking up thevalue of the DV and corresponding IVs and CVs for a subregime-country-yearMany IVs for example membership or annual percentage change in GNP arewhat are called ldquoindividual time-varying variablesrdquo42 that vary by both countryand year (both columns and rows differ) Other ldquoindividual time-invariant vari-ablesrdquo vary by country but only slowly by year such as administrative capacity

Ronald B Mitchell middot 75

40 Ostrom 1990 and Mitchell 199941 Hamerle and Ronning 199542 Hamerle and Ronning 1995 and Finkel 1995

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

or level of development and are captured in matrices in which the value for agiven country is the same for all years but those values vary across countries(rows differ but columns do not) ldquoPeriod individual-invariant variablesrdquo in-volve time-specic differences that affect all countries equally such as changesin regime features and changes in world oil and coal prices and can be capturedin matrices in which all countries have the same values for a given year but val-ues vary across years (columns differ but rows do not) Tables 3 through 6 pro-vide examples of these variables

What are the advantages of panel data for evaluating the effects and effec-tiveness of regimes Consider efforts to estimate how membership inuencesstate behavior Cross-section data would estimate this effect by comparingmember behavior to nonmember behavior failing to address the likelihoodthat member countries differ in systematic ways from nonmembers With cross-section data it proves difcult to decipher whether ldquobetterrdquo behavior by mem-bers reects the inuence of membership or the fact that those most willing andable to alter their behavior become members Even with proxies for such will-ingness or ability included in the model the possibility remains that memberand nonmembers differ in some systematic but unobserved way In contrasttime-series data estimates the membership effect by comparing the behavior ofstates as members to their behavior as nonmembers controlling for other fac-tors This approach ignores the possibility that other inuences that occur con-temporaneously with becoming a member (for example the end of the ColdWar in the LRTAP sulfur case) explain the change in behavior Regression usingtime-series data cannot distinguish whether membership or the other factor isresponsible for any behavioral differences

Panel data mitigates these problems by taking advantage of both types ofvariation simultaneously Panel data uses changes in nonmember behavior overtime to estimate how time-varying factors would have effected member behav-ior thereby avoiding erroneously attributing those effects to membership Paneldata controls for country-specic factors by using changes in behavior duringthe period in which a country was not a regime member to estimate how its be-havior would have been driven by non-regime factors when it was a memberthereby avoiding erroneously attributing those effects to membership Thuspanel data improves our estimate of regime effects by more effectively separat-ing regime effects from those due to time or country variables Fortunatelypanel data analysis can be undertaken with observations over only two or threetime periods although multi-year panels are certainly desirable43

Finally panel data analysis improves our ability to make causal inferencesby permitting explicit evaluation of time-dependency through lagged vari-ables44 Panel data can allow assessment and estimation of measurement error

76 middot A Quantitative Approach to Evaluating International Environmental Regimes

43 Finkel 199544 Finkel 1995

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

Ronald B Mitchell middot 77

Table 3Example of a Independent Variable of Interest

Independent variable of interest that is individual time-varyingExample ldquoMembershiprdquo based on entry into force

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

SOx Austria 0 0 1 1 1 1 1 1SOx Belgium 0 0 0 0 1 1 1 1SOx Canada 0 0 1 1 1 1 1 1SOx Iceland 0 0 0 0 0 0 0 0NOx Austria 0 0 0 0 0 0 1 1NOx Belgium 0 0 0 0 0 0 1 1NOx Canada 0 0 0 0 0 0 1 1NOx Iceland 0 0 0 0 0 0 0 0

Tables 4 5 and 6Examples of Three Types of Control Variables

Control variables that are individual time-invariantExample Land Area (000s of sq kilometers)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 839 839 839 839 839 839 839 839All Belgium 305 305 305 305 305 305 305 305All Canada 99761 99761 99761 99761 99761 99761 99761 99761All Iceland 103 103 103 103 103 103 103 103

Control variables that are period individual-invariantExample World Oil Price Index ($bbl)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 1435 79 976 812 1077 1235 1207 1313All Belgium 1435 79 976 812 1077 1235 1207 1313All Canada 1435 79 976 812 1077 1235 1207 1313All Iceland 1435 79 976 812 1077 1235 1207 1313

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

in the variables in the model a problem particularly likely with the social sci-ence data likely to be used in studies of regime effectiveness It also allows evalu-ation and correction for auto-correlation induced if both the dependent vari-able and included independent variables are functions of an omitted variablethereby permitting assessment of whether the model is properly specied45

Finally panel data allows evaluation of heteroskedasticity across the observa-tions in the data set

Availability of Data

Given what I hope are theoretically-compelling strategies for selecting the unitsof analysis identifying DVs and IVs and conducting the analysis the questionremains whether enough regimes with enough data exist to make quantitativeanalysis possible The answer is a resounding yes First several behavioral or en-vironmental quality data sets exist that can provide the foundation for calculat-ing APC gures In the LRTAP case data on sulfur dioxide nitrogen oxides andvolatile organic compounds are available for an average of 30 countries per yearfor the period 1980ndash1997 representing almost 1600 analysis units (30 coun-tries for 18 years for 3 protocols) Similar levels of detail are available for theMontreal Protocol and CFC production Fisheries whaling and other marinemammal data sets include most countries of the world for periods spanning upto 50 years allowing evaluation and comparison of the many correspondingagreements Some less detailed data is available on catch and in some in-stances populations (such as annual bird counts) relevant to many agreementson bird and land animal preservation

Grounds for guarded optimism also exist regarding PUE gures Mostsheries regimes have historical catch per unit effort information46 Researchersat IIASA have estimated abatement costs based on different scenarios for a range

78 middot A Quantitative Approach to Evaluating International Environmental Regimes

Control variables that are individual time-varyingExample GNP per capita (000s of constant 1995$)

Subregime Country 1985 1986 1987 1988 1989 1990 1991 1992

All Austria 236 241 245 252 262 271 276 277All Belgium 223 227 232 243 251 257 261 264All Canada 173 175 181 187 187 185 180 178All Iceland 230 244 264 255 255 256 257 247

45 Finkel 1995 8146 Peterson 1993

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

of countries and years that could serve as PUE estimates for European andNorth American acid precipitant regimes47 Sprinz and Vaahtoranta generatedcountry-specic abatement costs for the ozone and acid rain regimes48 Data setsthat could serve as at least rudimentary PUE estimates may well exist for otherregimes since they correspond so closely to the costs of environmental controlThe success of IIASA analysts and Sprinz at estimating abatement costs usingboth sophisticated modeling and more rudimentary proxy variables suggeststhat efforts in this direction are likely to bear at least some fruit

On the IV side data on treaty entry into force and country membershipare readily available for all treaties Several analysts have already coded particu-lar regime features for a range of environmental regimes including data on in-stitutional structure monitoring and enforcement data that could easily befurther enhanced through more systematic coding of environmental treaties49

Country-year data are also available on a wide variety of political and economicvariables that are central to any model of environmental behavior includingvarious permutations of GNP population energy use type of government andlevel of development with most available in electronic format Even acknowl-edging that the mismatch of data on DVs and IVs would further reduce the set ofusable observations due to missing values for various observations a carefullycleansed data set seems likely to yield enough country-year observations to pro-duce a collective data set with several thousand observations

Other regimes we want to evaluate however will have no data data foronly a few years or a few countries or data of such poor quality that it wouldmake little sense to use it What can we do in such situations The obvious an-swer is to recognize the inability to analyze such regimes in the short term andattempt to establish data collection systems that will allow such analysis in thefuture An alternative possibility however involves a more careful and iterativesearch for data by identifying indicators relevant to the effectiveness of a givensubregime and determining whether they are available and reciprocally identi-fying available data sets and determining to which subregimes they might berelevant Such a process may uncover nonobvious variables that are both rele-vant and available to support the use of quantitative analysis to evaluate re-gimes As most case study scholars know extensive relevant data turns up formany regimes if sufcient research time is invested A systematic attempt towork with such scholars could take advantage of their knowledge of individualdata sets to create a meta-database of environmental indicators for analysis50

Indeed the belief that relevant data sets do not exist may owe more to the as-

Ronald B Mitchell middot 79

47 Alcamo et al 199048 Sprinz and Vaahtoranta 199449 For example databases created by Peter Haas Dimitris Stevis Edith Brown Weiss and Harold Ja-

cobson and the International Regimes Database all have systematic codings of several variablesfor various environmental treaties See Haas and Sundgren 1993 401ndash429 Brown Weiss and Ja-cobson 1998 Victor Raustiala and Skolnikoff 1998 and Stevis 1999

50 The author is currently in the process of developing such a project

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

sumption that quantitative analysis is not possible than to the real unavailabil-ity of such data

Conclusion

Quantitative analysis offers the opportunity to investigate certain aspects of re-gime consequences in ways that are not easily examined using qualitative tech-niques Although factor analysis contingency tables and other techniques arecertainly possible and should be explored the present article has investigatedthe contribution that regression analysis using panel data could make to deter-mining whether and which type of regimes are most effective Studies that col-lect data on a range of regimes and subregimes provide valuable means of iden-tifying general trends across regimes (eg ldquoare regimes usually effectiverdquo) forevaluating whether some regimes are more effective than others and for deter-mining how non-regime factors condition the ability of a particular type of re-gime to be inuential Although these questions could be answered by qualita-tive case studies they are questions that are particularly suitable to large-Nquantitative techniques

Stating that quantitative techniques can complement qualitative analysesand contribute to the regime consequences research project does not meanhowever that undertaking such analyses will be easy Indeed the foregoing ar-gument has sought to identify and clarify the numerous theoretical and empiri-cal obstacles to using quantitative analysis to answer questions central to the re-gime effectiveness research program Devising a dependent variable that wouldallow meaningful comparison across regimes requires careful attention to creat-ing a comparable metric of change and a comparable metric of difculty orregime effort per unit change Likewise representing regime inuence in themodel requires careful specication if we are to determine how regimes inu-ence members how they inuence nonmembers and how their inuences dif-fer across the two Comparing across regimes also requires careful attention tospecication of non-regime control variables A model designed to apply to allregimes is likely to produce weak and perhaps uninterpretable estimates of re-gime effects one designed to apply well to a single regime precludes compari-son across regimes Intermediate models specied to explain the variation in thedependent variable across a set of regimes that are selected for similarity in theirpredicted impacts may reach the right balance between these too-generic andtoo-specic extremes Applying such a model to panel data using subregime-country-years as our observations allows us to control for variables in waysthat more aggregated analyses cannot Such data appears to be available at leastfor enough regimes to make the enterprise worth pursuing A well-speciedmodel and corresponding data would allow us to evaluate whether regimesinuence states whether they do so in ways that would be unlikely to have oc-curred by chance which ones do so better than others and a variety of as yet

80 middot A Quantitative Approach to Evaluating International Environmental Regimes

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

unidentied but important questions The opportunities if not endless are outthere

References

Alcamo J R Shaw and L Hordijk eds 1990 The RAINS Model of Acidication Scienceand Strategies in Europe Dordrecht Kluwer Academic Publishers

Asher H B 1976 Causal Modeling Beverly Hills Sage PublicationsBiersteker T 1993 Constructing Historical Counterfactuals to Assess the Consequences

of International Regimes The Global Debt Regime and the Course of the Debt Cri-sis of the 1980s In Regime Theory and International Relations edited by V Rittberger315ndash338 New York Oxford University Press

Brown Weiss E and H K Jacobson eds 1998 Engaging Countries Strengthening Compli-ance with International Environmental Accords Cambridge MA MIT Press

Chayes A and A H Chayes 1993 On Compliance International Organization 47 175ndash205

_______ 1995 The New Sovereignty Compliance with International Regulatory AgreementsCambridge MA Harvard University Press

Cohen J 1992 A Power Primer Psychological Bulletin 112 155ndash9Downs G W D M Rocke and P N Barsoom 1996 Is the Good News about Compli-

ance Good News about Cooperation International Organization 50 379ndash406_______ 1998 Managing the Evolution of Cooperation International Organization 52

397ndash419Eckstein H 1975 Case Study and Theory in Political Science In Handbook of Political Sci-

ence Vol 7 Strategies of Inquiry edited by F Greenstein and N Polsby 79ndash137Reading MA Addison-Wesley Press

Fearon J D 1991 Counterfactuals and Hypothesis Testing in Political Science WorldPolitics 43 169ndash95

Finkel S E 1995 Causal Analysis with Panel Data Thousand Oaks CA SageGaltung J 1967 Theory and Methods of Social Research New York Columbia University

PressHaas P M and J Sundgren 1993 Evolving International Environmental Law

Changing Practices of National Sovereignty In Global Accord Environmental Chal-lenges and International Responses edited by N Choucri 401ndash429 Cambridge MAMIT Press

Haas P M R O Keohane and M A Levy eds 1993 Institutions for The Earth Sources ofEffective International Environmental Protection Cambridge MA MIT Press

Hamerle A and G Ronning G 1995 Panel Analysis for Qualitative Variables In Hand-book of Statistical Modeling for the Social and Behavioral Sciences edited byG Arminger C C Clogg and M E Sobel 401ndash451 New York Plenum Press

Harbaugh W A Levinson and D Wilson 2000 Re-examining the Empirical Evidence foran Environmental Kuznets Curve Cambridge MA National Bureau of Economic Re-search

Helm C and D Sprinz 1999 Measuring the Effectiveness of International EnvironmentalRegimes Potsdam Potsdam Institute for Climate Impact Research May

Hufbauer G C J J Schott and K A Elliott 1990 Economic Sanctions Reconsidered His-tory and Current Policy Washington DC Institute for International Economics

Ronald B Mitchell middot 81

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

Kenny D A 1979 Correlation and Causality New York John Wiley and SonsKing G R O Keohane and S Verba 1994 Designing Social Inquiry Scientic Inference in

Qualitative Research Princeton NJ Princeton University PressKrasner S 1983 International Regimes Ithaca Cornell University PressLevy M A 1993 European Acid Rain The Power of Tote-Board Diplomacy In Institu-

tions for the Earth Sources of Effective International Environmental Protection editedby P Haas R O Keohane and M Levy 75ndash132 Cambridge MA MIT Press

_______ 1995 International Cooperation to Combat Acid Rain In Green Globe YearbookAn Independent Publication on Environment and Development edited by F N Insti-tute 59ndash68

Meyer J W D J Frank A Hironaka E Schofer and N B Tuma 1997 The Structuringof a World Environmental Regime 1870ndash1990 International Organization 51 623ndash629

Miles E L A Underdal S Andresen J Wettestad J B Skjaerseth and E M Carlin eds2001 Environmental Regime Effectiveness Confronting Theory with Evidence Cam-bridge MA MIT Press

Mitchell R B 1994 Intentional Oil Pollution at Sea Environmental Policy and Treaty Com-pliance Cambridge MA MIT Press

_______ 1996 Compliance Theory An Overview In Improving Compliance with Interna-tional Environmental Law edited by J Cameron J Werksman and P Roderick 3ndash28London Earthscan

_______ 1999 International Environmental Common Pool Resources More Commonthan Domestic but More Difcult to Manage In Anarchy and the Environment TheInternational Relations of Common Pool Resources edited by J S Barkin andG Shambaugh Albany NY SUNY Press

Mitchell R B and T Bernauer 1998 Empirical Research on International Environmen-tal Policy Designing Qualitative Case Studies Journal of Environment and Develop-ment 7 4ndash31

Murdoch J C T Sandler and K Sargent 1997 A Tale of Two Collectives Sulphur Ver-sus Nitrogen Oxides Emission Reduction in Europe Economica 64 281ndash301

Ostrom E 1990 Governing the Commons The Evolution of Institutions for Collective ActionCambridge England Cambridge University Press

Peterson M J 1993 International Fisheries Management In Institutions For The EarthSources of Effective International Environmental Protection edited by P Haas R OKeohane and M Levy 249ndash308 Cambridge MA MIT Press

Princen T 1996 The Zero Option and Ecological Rationality in International Environ-mental Politics International Environmental Affairs 8 147ndash76

Ragin C C and H S Becker 1992 What is a Case Exploring the Foundations of Social In-quiry Cambridge England Cambridge University Press

Sprinz D 1998 Domestic Politics and European Acid Rain Regulation In The Politics ofInternational Environmental Management edited by A Underdal 41ndash66 DordrechtKluwer Academic Publishers

Sprinz D and C Helm 1999 The Effect of Global Environmental Regimes A Measure-ment Concept International Political Science Review 20 359ndash69

Sprinz D and T Vaahtoranta 1994 The Interest-Based Explanation of International En-vironmental Policy International Organization 48 77ndash105

Stevis D 1999 Email communication

82 middot A Quantitative Approach to Evaluating International Environmental Regimes

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83

Stokke O S 1997 Regimes as Governance Systems In Global Governance Drawing In-sights from the Environmental Experience edited by O R Young 27ndash63 CambridgeMA MIT Press

Tabachnick B G and L S Fidell 1989 Using Multivariate Statistics New YorkHarperCollins Publishers

Underdal A 2001 Conclusions Patterns of Regime Effectiveness In Environmental Re-gime Effectiveness Confronting Theory with Evidence edited by E L Miles et al Cam-bridge MA MIT Press

Underdal A and O R Young eds Forthcoming Regime Consequences MethodologicalChallenges and Research Strategies Dordrecht Kluwer Academic Publishers

Victor D G K Raustiala and E B Skolnikoff eds 1998 The Implementation and Effec-tiveness of International Environmental Commitments Cambridge MA MIT Press

Wettestad J 1999 Designing Effective Environmental Regimes The Key ConditionsCheltenham UK Edward Elgar Publishing Company

Yin R 1994 Case Study Research Design and Methods 2nd ed Newbury Park Sage Publi-cations

Young O R ed 1997 Global Governance Drawing Insights from the Environmental Experi-ence Cambridge MA MIT Press

_______ ed 1999a Effectiveness of International Environmental Regimes Causal Connec-tions and Behavioral Mechanisms Cambridge MA MIT Press

_______ 1999b Governance in World Affairs Ithaca NY Cornell University Press

Ronald B Mitchell middot 83