HEALTH EDUCATION RESEARCHTheory & Practice

Vol.6 no.2 1991Pages 163-171

Conceptual models for health education research andpractice

Jo Anne Earp and Susan T.Ennett

Abstract Introduction

Although conceptual models are frequently usedto illustrate research questions under investiga-tion, there is a paucity of articles about how todevelop conceptual models or their importance tohealth education research and practice. A numberof uses of the term model exist. Therefore, wedescribe a conceptual model developed to guidehealth education research or practice as a diagramof proposed causal linkages among a set ofconcepts believed to be related to a specific publichealth problem. Although informed by themulticausal models of public health, the concep-tual models we describe differ from those modelsin that they do not incorporate all factorscorrelated with an endpoint of interest. Ratherthey show only the small part of the causal webselected for study. Conceptual models differ fromtheory in that they are not usually concerned withglobal classes of behavior but with specific typesof behavior in specific contexts. They often areinformed by more than one theory, as well as byempirical findings. Because of the usefulness ofconceptual models in narrowing both researchquestions and the targets of intervention, weadvocate the inclusion of the model developmentprocess in public health education researchmethods courses.

Department of Health Behavior and Health Education,School of Public Health, University of North Carolina atChapel Hill, Chapel Hill, NC 27599, USA

Over the span of several years, during the annualprocess of preparing to teach a basic researchmethods course in public health education, thepaucity of articles on why, when and how toconstruct conceptual models became all too apparent.It was not that we lacked examples of such heuristicdevices; historically many articles, some of themclassics in the health services and medical careresearch fields, have included conceptual diagramsof research questions. Social science-minded healtheducators usually insist upon the inclusion of suchmodels in their own, their students and, as reviewers,their colleagues' research proposals.

Yet we searched the literature in vain for anyarticle that defined, in simple, public health-relevantterms, what a conceptual model is, how it differsfrom a theory, why it is particularly relevant to publichealth and how to go about developing one.Therefore, each year we decided, once again, toassign Daniel Horn's (1976) paper, "A Model forthe Study of Public Choice Health Behavior", evenas it was supplanted by newer, perhaps more rele-vant (although not more elegant) models forexplaining or predicting health behavior (Prochaskaand DiClemente, 1982) or for planning andimplementing health education interventions (Greenet at., 1980). Although not answering specificallythe above questions, the Horn article still did the mostthorough job of illustrating what a model is anddiscussing its public health origins.

Using the Horn article and handouts of modelsgoing back almost 25 years to Suchman's (1965)framework for health behavior, Graham andReeder's (1972) "Social Factors in Chronic

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Diseases", which organized the multiple deter-minants of cancer of the scrotum by levels ofcausality, through Anderson et al.'s (1970) modelfor medical care and Rosenstock's (1974) healthbelief model, we certainly did not lack examples.However, neither Horn's model nor the handoutswere specific enough to allow students to walk awayfrom the course able to design their own conceptualmodels or even, more basically, to understand whyusing a model helped them as both researchers andpractitioners. Hence, we decided to write such anarticle ourselves. In it, we discuss how we definea conceptual model, why we believe conceptualmodels are particularly appropriate to public health,how they aid in planning research or interventions,how to develop a useful conceptual model, somebarriers to their acceptance and use, and recommen-dations for learning how to work with conceptualmodels.

Definition

Before we describe how to define the term concep-tual model, we should note that the term model hasmany different uses and meanings. Included amongthese are: a conceptual framework for organizing andintegrating information; a diagrammatic system ofmeasurement (i.e. mathematical and statisticalmodels); and a conceptual structure successfullydeveloped in one field and applied to some other fieldto guide research and practice (i.e. an analogy)(Marx, 1976). Also, the term model often is usedinterchangeably with the term theory or is used tomean the visual representation of the elements of atheory.

Our working definition of conceptual modelderives primarily from the first usage. We define aconceptual model as a diagram of proposed causallinkages among a set of concepts believed to berelated to a particular public health problem. By

concept (also referred to as a factor or variable), wemean an abstract term able to be empirically observedor measured. Hence, a conceptual model, throughconcepts denoted by boxes and processes delineatedby arrows, provides a visual picture that representsa research question under investigation or the presentfocus of a specific intervention effort. A conceptualmodel can be informed by more than one theory andconceptualized at multilevels (from micro to macro).As importantly in an applied field, it allows the inclu-sion of processes or characteristics not grounded informal theory, but that represent empirical findingsor the experience of practicing professionals.

As an example, we use a simple model ofcompliance that we have used in class (Figure 1).The concepts in this model are the communicationbetween a physician and patient, the patient'sunderstanding of a treatment and the patient'scompliance with a medical regimen. The arrows, bytheir directionality, indicate that the communicationbetween a doctor and patient influences the patient'sunderstanding of some recommended treatmentwhich, in turn, influences the patient's compliance.It is clear from the model that physician—patientcommunication is the predictor variable, or the'cause', and that compliance is the dependentvariable, or the 'outcome'. As the model is concep-tualized, the patient's understanding of the regimenis a mediating variable (i.e. an intervening,explanatory variable or process between the predictorvariable and the outcome).

Of course, as students are quick to point out, thisis an incomplete and unrealistic model. There areother factors certain to affect compliance eitherdirectly or indirectly. For example, the degree ofdifficulty for the patient in carrying out the regimen,whether cost is covered by medical insurance, orparticular characteristics of the condition, such aswhether it is symptomless, could affect compliance.Also, compliance could be affected by factors that

Physician-PatientCommunication

Fig. 1. Simple three-variable conceptual model.

PatientUnderstanding

of RegimenCompliance

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influence physician-patient communication. Forexample, does educational level of the patient orwhether the doctor and patient are of the same genderaffect communication and, in turn, compliance?Clearly, the model becomes more complex asvariables are added that the investigator feels areneeded to account for the outcome (Figure 2).

Models and the ecological perspective

As health educators we believe an ecological perspec-tive is needed for understanding and explaininghealth-related behaviors. This perspective impliesthat behavior results from the interaction of both

Physician &Patient Gcnden

Physician-PatientCommunication

individual and environmental determinants (McLeroyet al., 1987). Indeed, virtually any health behavior,be it patient compliance, smoking, AIDS-related orany of many others, results from a multitude offactors arising from biological, psychological, social,cultural and structural spheres. Thus, in planningresearch and intervention efforts, we need to considernot only individual, microlevel factors, but influen-tial environmental and social forces that act, inconcert, on individuals who are part of groups.Health education models frequently reflect thisperspective by including factors at multiple levels ofinfluence.

The ecological perspective of health education is

PatientUnderstandingof Regimen Compliance

Fig. 2. Five-vanable conceptual model showing modifyingand confounding variables.

Epidemiologlcal Model

Complexityof

Regimen

Ecological Model

AGENT

ENVIRONMENT HOST

Fig. 3. MulticausaJ models of public health (from Susser.1973).

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mirrored by the classic public healthagent —host —environment model and, morecurrently, in multicausal models (Figure 3), whichde-emphasize the agent but elaborate on environmentas a web of reciprocal relationships among factors(MacMahon and Pugh, 1970; Susser, 1973). Yetthese models, while informing how we conceptualizehealth problems, are not to be taken as literalexamples of the conceptual models we are advocatingfor application to health education research and prac-tice. Multicausal models of public health illuminatethe complexity of health problems and help ourunderstanding of the dynamic inter-relationships thatsustain disease, but they pose a dilemma for construc-ting models that apply to health education researchand practice. With multicausal models it is oftendifficult to sort out relationships, much less direc-tionality or causation. Indeed, that is not their point.Rather, their purpose is to call attention to the playof factors at multiple levels, the inevitable interac-tion among correlates and the fact that such concep-tions stand in contrast to germ theory or medicalmodels of causation with their usual unidirectional,univariate agents of disease causality (Cassel, 1964).

For behavioral-science-trained health educators,conceptual models must be, at once, both conceivedwithin the broadly based framework of multicausalmodels and more specifically defined when appliedto the explication or solution of problems of interest.In constructing conceptual models for health educa-tion research and practice, we must be attentive tothe multiple determinants of health behaviors and thecomplex inter-relationships among factors; at thesame time we also must be willing to fix an'endpoint' or outcome of interest and move back-wards from it to selected determinants, ruling outothers. Our point is to cut into the multiple levelsand myriad possible determinants, to show only asmall part of the causal chain rather than to depictthe entire causal process. This contrasts with—indeed, it may seem to contradict—the point ofreciprocal interactions that multicausal models show.It means we have to limit our scope and fix our focus,even while being aware of the larger causal websurrounding our particular research question orintervention effort. Our conceptual models will

almost certainly not incorporate all the factors thatrelate to our endpoint, but will show the relation-ships for only that small part of the causal web wehave selected for study or have targeted for change.

The relationship betweenmodels and theories

Although the term model is often used loosely tomean theory, conceptual models and theories are notthe same. Theories consist of one or more generaland logically inter-related propositions offered toexplain a class of phenomena (Bauman, 1980). Theyare usually concerned with very general and globalclasses of behavior and do not deal directly, asconceptual models do, with specific types of behaviorin specific contexts. Also, theories generally repre-sent reality from a discipline-specific perspective, bethat sociological, economic or biological. Becausethey are discipline-specific, theories often specifylevel-specific causes.

Our concerns in health education virtually dictatethat we cannot apply or test only one theory fromone discipline, nor can we delimit the levels ofcausality—hence the usefulness of conceptualmodels. In developing conceptual models, we oftendraw on a number of theories for help in understand-ing a specific problem in a particular setting orcontext. Furthermore, we draw on empirical findingsand on the knowledge we may have about the specifictopic and context under consideration. Although thedomain of interest of our conceptual models is usuallynarrower than that of theories, it is important to notethat models have several similar functions to theories.Conceptual models are useful for summarizing andintegrating the knowledge we have, definingconcepts, providing explanations for causal linkagesand generating hypodieses.

An important role of theory in model developmentis guidance on narrowing the concepts to include inthe model and for help in understanding and predic-ting relationships. A recent investigation, forexample, of parental influences on adolescentsmoking (Foshee, 1989) was informed by both socialcontrol theory (Hirschi, 1969) and social learningtheory (Bandura, 1971). Social control theory states

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that the more adolescents are attached to family andfriends, committed to conventional activities, andbelieve in the conventional rules of society, the lesslikely they are to deviate from conventional behavior.The behavior of significant others, either family orfriends, is not included in control theory but has beenconsistently found to be a strong predictor of adoles-cent smoking behavior. Social learning theory,however, states that parents and peers influenceadolescent behavior by providing models to imitateand by expressing favorable or unfavorable attitudestoward the behavior. Hence, a new model for predic-ting adolescent cigarette smoking was proposed thatincorporated processes of both theories (Figure 4).

This example demonstrates the utility of usingtheory to provide guidance on the choice of conceptsfor investigation and for specifying the relationshipsto be expected. It also demonstrates that a singletheory is usually insufficient to incorporate allvariables of interest to conceptual models in healtheducation. Expecting this to be so, model buildersshould be open to using several theories as well aspast research findings. Model building then becomesa process of invention, subject to modification as newfindings emerge that confirm or redirect howproblems are conceptualized.

Use of models

Susser (1973) describes several uses of public healthmodels pertinent to our discussion, includingrepresentational, organizing and explanatory func-tions. As health educators, we also include theirusefulness in planning interventions. The represen-tational function of models is to present, in asimplified form, relationships believed to exist. Partand parcel of conceptual models' representationalfunction is their usefulness as organizing tools.According to Susser, they "organize and synthesizea complex of related factors into coherent forms"(1973, p. 33). The best models parsimoniouslyconvey complex information, allowing the viewer toquickly visualize and grasp complicated relationships.At their most practical level conceptual models helpto narrow global research topics into specific researchquestions, designate variables to be operationalizedunder particular conditions and anticipate analyticalapproaches before the sample is chosen or the datacollected.

As conceptual models are developed, they servean important function in making explicit alternativeroutes to the same endpoint. When we constructmodels, we inevitably struggle with including some

Commitmentto

Conventional Activities

Belief inConventional Rules

ofSociety

Fig. 4. Conceptual model incorporating processes from social control theory and social learning theory (Foshee, 1989).

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concepts and excluding others, and with posingdifferent relationships between concepts. Some ofdiese may be valid alternatives to those selected forstudy or intervention. By using models to reasonthrough alternative explanations before implemen-ting our research, we have the opportunity to gatherdata needed to control confounding factors or to testthese alternative pathways. At the least, we becomeaware of potential influences beyond the specificfactors under study.

Finally, conceptual models are extremely usefulfor helping identify potential targets of intervention.Aldiough a model does ot tell us how to intervene,it does make clear where intervention efforts can beaimed. The more comprehensive the model, thegreater the number of points and levels of interven-tion suggested. Depending on where efforts arefocused, we can look at die linkages shown in ourmodel and speculate on the intervention's effects onthese relationships.

Developing a conceptual model

Using an existing model as a starting point and/orbeginning with a comprehensive inventory of riskfactors, the researcher or intervention planner beginsdeveloping a conceptual model by specifying anendpoint of interest—the dependent variable,outcome or target point of intervention. Smokinginitiation, for example, is a different endpoint frompersistent smoking behavior, attitudes towardsmoking or smoking cessation. The model buildermay change or move the endpoint, as the concep-tual model is fleshed out, to be more proximal tothe predictors selected or more practical. Eventhough the endpoint might change, however, themodel development process cannot really start untilsome outcome is selected.

Having chosen the endpoint of interest, the modelbuilder begins by selecting potential correlates andproceeds by sorting out at least initial relationshipsamong those concepts. Linkages among concepts aredrawn, based on empirical and theoretical evidence,as well as on the knowledge one may have about thespecific topic under consideration. Causal explana-tions are made explicit by the directionality of arrows

connecting concepts. It is at this point that the modelbuilder usually must begin to pare down a probably-too-global, too unwieldy, set of concepts to thoseparticular aspects of the problem that he or shedecides can be realistically addressed in this researcheffort or intervention strategy. The choice will beaffected by many considerations: interest, practicalconsiderations, the relative importance of variousfactors or relationships, past research and scientificmerit, and theoretical considerations.

The process of narrowing the concepts in themodel is one of die most difficult steps in its develop-ment. The investigator is usually forced to accept thatthere are alternative routes to the endpoint of interestor complementary causal pathways to the one(s)selected for focus. This process of reasoning throughwhat is important and what to leave in or take outof the model should make clear to the investigatoror practitioner exactly what is not being investigated.As noted earlier, this knowledge can be useful inplanning what additional information to gather or forlater suggesting explanations for unanticipatedintervention effects or contradictory researchfindings.

The simplicity of die final product usually beliesthe difficult work that goes into it. As we hope isobvious, the process of developing a conceptualmodel requires clear understanding of what is beingconsidered, for the model explicitly lays out conceptsof interest and anticipated relationships even as itdeliberately omits other factors and pathways.

Although the analysis and thought behind concep-tual models are rarely simple, the conventions fordrawing them are. For models constructed forresearch purposes, only concepts that will be opera-tionally defined and measured are included in thefinal model; all other concepts not direcdy consideredare excluded. For models that guide intervention, allfactors targeted by the intervention or expected tobe influenced by it are shown. Because of the usuallygreater diversity and number of levels involved,intervention models often will be more complicatedthan diose drawn for research purposes.

Conceptual models generally are read from left toright or up to down, going from causes to effects.The direction of causality is indicated with arrows.

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Antecedent or mediating variables are indicated bytheir placement next to other variables. Confoundingvariables, variables that affect the dependent variableand vary with a predictor variable, are shown by aline or double-headed arrow (if the direction ofcausality is not known) drawn from the confounderto both the dependent and predictor variables. Avariable thought to modify the relationship betweentwo variables is indicated by an arrow drawn to themidpoint of the line connecting the two relatedvariables (Figure 5).

Labels of concepts or variables included in themodel should be succinct; neither operational defini-tions nor the values of variables are shown. Forexample, a model could show that 'peer smokingbehavior' is related to 'adolescent smoking initiation',but the hypothesis that having more than twosmoking friends is related to earlier smoking initia-tion, while having two or fewer smoking friends isnot, should not be indicated (Figure 6). Hypothesesare stated in the text accompanying models, as arethe values of all variables shown in the model.

It can be helpful to remember that constructing aconceptual model is as much an art as a science.

AntecedentVariable

PredictorVariable

PredictorVariable

MediatingVariable

ConfoundingVariable

DependentVariable

DependentVariable

PredictorVariable

Dependent-•• Variable

ModifyingVariable

PredictorVariable

DependentVariable

Fig. 5. Types of relationships between variables in conceptualmodels.

Making the model visually pleasing helps in makingit readable and understandable. Boxes drawn aroundconcepts make the model easy to interpret, as doboldface type, different type fonts and other computergraphic features. Usually, several attempts areneeded to arrive at a pleasing and meaningful model.It is probably no coincidence that where the modelbuilder stumbles in this process is often a good clueto where conceptual clarity is lacking.

Barriers to developing and using models

We have already alluded to the biggest barrier indeveloping conceptual models: clarity and rigor ofthinking are required. Explicating the mechanismsof action of a set of concepts is very difficult. Itinvolves learning to 'think small' and learning howsmall is small, giving up many favorite concepts tonarrow the scope, and choosing a realistic endpointthat is still conceptually interesting and defensible.The outcome first chosen, until one learns fromexperience, is usually too gross. For many people,the initial feedback about this outcome, or othertypical problems encountered in constructing amodel, may not be accompanied by suggested alter-natives. Without such suggestions, it can be difficultto make refinements on one's own.

Many health educators are uncomfortable withdeveloping and using conceptual models becausetheir exposure to them and experience using themare limited. When models are taught, the process istoo often truncated at the intellectual level. Studentsrarely have the 'hands on' learning experience ofdeveloping and refining a model after being exposedto a classroom lecture on the model developmentprocess. To our knowledge, no published collectionof public health or health education models exists forinstructors to use with students.

Furthermore, guidelines that point to what is leftout of a model are non-existent. Many people usethe agent—host—environment or multicausal modelssuch as PRECEDE (Green et al., 1980) as startingpoints for conceptualizing health problems.However, as McLeroy et al. (1987) note, multicausalmodels lack sufficient specificity to guide concep-tualization of a specific research question or to iden-

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Friends' SmokingBehavior

CORRECT

Tetn SmokingInitiation

>2 SmokingFrtenda

S 2 SmokingFriendj

INCORRECT

Earlier-SmokingInitiation

LaterSmokingInitiation

Fig. 6. Correct conceptual model showing concepts; incorrect model showing values of variables.

tify appropriate and feasible interventions. In fact,taking a multicausal approach may be paralyzing byits immensity and tendency to assign equal weightsto all factors. Citing some of the shortcomings ofusing the multicausal model to direct disease preven-tion policy, Tesh (1988) observes that " . . . themulticausal model easily becomes a rationale for nottaking action" (p. 62) because the maze of connec-ting links seems to require that prevention policyattack all causes at once, an impossible strategy.

Recommendations

Our recommendations for learning how toappreciate, develop and use conceptual models arefirst to look at examples of models developed forhealth education research or practice and to practiceworking with your own. For example, we givestudents a health behavior or health educationoutcome and have them come up with a list ofcorrelates of that outcome. They group theseconcepts into conceptually similar clusters, nameeach cluster, and finally draw arrows to indicate theconnections they think are most logical between theirset of concepts and the outcome. A follow-up assign-ment involves drawing forth one or two researchquestions from the narrowed down model, followedby posing one or two hypotheses from each ques-

tion, and finally attempting to operationalize thevariables, including specifying their values and themethods that will be used to measure them.

At a more general or programmatic level, wesuggest that all basic research methods courses, atleast in public health education, avoid simplyteaching data collection methods, research designsand analytical techniques without putting thesetechniques in the context of using conceptual modelsto narrow a research area to a defined set of researchquestions. This, in turn, may mean we need to re-evaluate our basic methods courses and/or revampour approaches to the teaching of both theory andmethods in public health. Until professors themselvesbecome more comfortable with the design and useof conceptual models, it is unlikely that their studentswill think about using, much less struggling toconstruct, conceptual models to guide their researchor shape their program interventions and strategies.We hope this article represents one step to advancethese goals.

Acknowledgements

We would like to acknowledge KathleenWelshimer's contribution to the development of someof these ideas. Karl Bauman, Robert Flewelling,

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Vangie Foshee and Carol Runyan made helpfulcomments on an earlier draft of this paper.

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