2. research design-ldr 280_2.ppt
TRANSCRIPT
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LIHAM-PANGANGALAKAL
Ginagamitbilangtransiyunal na
ugnayan ngmga taong nasaloob ng isang
organisasyon.
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Layunin ng LihamLayunin ng Liham
Layunin nito upang mapanatili saLayunin nito upang mapanatili sapakikitungo sa mga kliyente ngpakikitungo sa mga kliyente ngkompanya.kompanya.
Maging daan ng mabilis na paraan ngMaging daan ng mabilis na paraan ngkomunikasyonkomunikasyon
Binigigyan diin dito ang mambabasa.Binigigyan diin dito ang mambabasa.
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15 Cs15 CsA. Candid , concrete tuiran, tiyak,matapat
B. Clear ! malina
C. Co"erent may kaisa"an ang mga ideya
#. Common, Con$incing, Cordial
%. Concerned, Concise, Considerate
&. Complete, Con$ersational
G. Correct, Courteous, Credible
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BAHAGI NG LIHAMBAHAGI NG LIHAM
Letter'eadLetter'ead
General #ata (e$icesGeneral #ata (e$ices
2)) Buendian A$e.2)) Buendian A$e.
*el. +o.*el. +o.
&!mail&!mail -etsa-etsa AddressAddress Linya para saLinya para sa
AttensyonAttensyon
(alutation(alutation (ubect Line(ubect Line /ataan/ataan ComlimentaryComlimentary
ClosingClosing CompanyCompany
(ignature(ignature 0riter0riter
dentiicationdentiication
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4eerence nitial4eerence nitial &nclosure 4eminder&nclosure 4eminder
Copy +otationCopy +otation
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Methods of ResearchMethods of Research
Descriptive ResearchDescriptive Research
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Historical ResearchHistorical Research
Experimental ResearchExperimental Research
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! is t"e critical in$estigation o e$ents,de$elopments and e:periences o t"e
past, t"e careul eig"ing o e$idenceo t"e $alidity o sources o inormationon t"e past and t"e interpretation ot"e eig"ed e$idence
Historical Research
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1)1)
Methods of Historical
Research
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a. Classiication o "istorical sources
b. 0"ere t"e sources are located
c. (ystemati;ing your note taking
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a.&:ternal Criticism
b. nternal Criticism
!in$ol$es inding out i t"e source material isgenuine and i it possesses te:tual integrity
!c"eck on t"e meaning and trustort"iness ot"e data it"in t"e documents
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DescriptiveResearch
describes t"e population
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Developing Research
Hypotheses
Intriguing Observation,
Intellectual Curiosity
Defining Research
Problem & Objectives
Testing Hypo!
Data "nalysis &
Interpretation
#ampling Design
Refinement of theory
$In%uctive Reasoning
Data Co%ing,
"n%'%iting
Developing Operational
Definitions for
Research (ariables
)uil%ing the Theoretical
*rame+or an% the
Research -o%el
Data Collection
-ore Careful #tu%ying
of the Phenomenon
THE PROCESS OF
EMPIRICAL RESEARCH
*'& -4=C&(( =% M-&4CAL4&(&A4C'
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Experimental Research
is a study conducted in t"elaboratory. %ield e:periments and>uasi! e:perimental researc" allunder t"is type.
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Questions or Comments
?
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RESEARCH DESIGNRESEARCH DESIGN
CONCLUSION VLIDI!"CONCLUSION VLIDI!"reers to t"e e:tent oreers to t"e e:tent oresearc"er?s ability toresearc"er?s ability to dra accurate conclusionsdra accurate conclusionsrom t"erom t"eresearc". *"at is, t"e degree o a study?sresearc". *"at is, t"e degree o a study?s
a#a# Internal Validit$Internal Validit$@@correctness o conclusionscorrectness o conclusionsregarding t"eregarding t"erelations"ips among $ariablerelations"ips among $ariables e:amineds e:amined0"et"er t"e researc" indings accurately relect "o t"e researc"0"et"er t"e researc" indings accurately relect "o t"e researc"
$ariables are really connected to eac" ot"er.$ariables are really connected to eac" ot"er.
a#a# External Validit$External Validit$Generali;ability o t"eGenerali;ability o t"e indings to t"eindings to t"eintendedappropriate populationsettinintendedappropriate populationsettingg
RESERCH DESI%NRESERCH DESI%N&& TheTheblueprint.roa%mapblueprint.roa%mapthat +ill gui%e thethat +ill gui%e theresearchresearch
The test for theThe test for the /uality of a stu%y0s research %esign/uality of a stu%y0s research %esign is theis the
stu%y0sstu%y0s concl'sion validit$concl'sion validit$..
PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (
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WhatWhat--What was studied?--What was studied? What aboutWhat about--What aspects of--What aspects of
the subject were studied?the subject were studied? What forWhat for--What is/was the--What is/was the
significance of the study?significance of the study?
What did prior lit./research say?What did prior lit./research say?
What was doneWhat was done--How was the--How was the
study conducted?study conducted?
What was found?What was found? So what?So what?
What now?What now?
1. ntroduction,
4esearc" -roblems
=becti$es, ustiication
2. Literature 4e$ie
3. Met"odologyD4esearc" sample, data
collection, measurement, data analysisE
. 4esults #iscussion
5. mplications
6. Conclusions and
4ecommendations or %uture 4esearc"
PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (PR!"SS # $"S%&'%'& ('$ !'$)!*%'& (R"S"(R!H PR+"!*,R"S"(R!H PR+"!*,
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2)2)
RESEARCH DESIGNRESEARCH DESIGN
F ariance o t"e +#&-&+#&+* #&-&+#&+*ariance o t"e +#&-&+#&+* #&-&+#&+*$ariables D$ariables DS$stematic VarianceS$stematic VarianceEE
F ariability o potential +H(A+C&&I*4A+&=H(ariability o potential +H(A+C&&I*4A+&=H(
C=+%=H+#+G $ariables DC=+%=H+#+G $ariables DConfo'ndin( VarianceConfo'ndin( VarianceEE
F ariance attributable to &44=4 + M&A(H4&M&+*ariance attributable to &44=4 + M&A(H4&M&+*
DDError VarianceError VarianceE.E.
'oJ'oJ
'o do you ac"ie$e'o do you ac"ie$einternal and external validit$internal and external validit$ Di.e.,Di.e.,conclusion $alidityEJconclusion $alidityEJ
By eecti$elyBy eecti$ely controllin( ) t$pes ofcontrollin( ) t$pes of variancesvariances
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!$pes
of DescriptiveResearch
a. (ur$ey. A sur$ey is used"en t"e obecti$es o t"e studyis to see a general speciic
picture o t"e population underin$estigation in terms o t"eirsocial and economic
c"aracteristics
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Effective Research DesignEffective Research Design
MAIMAIimi;e (ystematic arianceimi;e (ystematic ariance
M+M+imi;e &rror arianceimi;e &rror ariance
C=+C=+trol ariance o +uisance&:traneoustrol ariance o +uisance&:traneous&:ogenousConounding $ariables&:ogenousConounding $ariables
Guiding principleGuiding principleor eecti$e control oor eecti$e control o$ariances Dand, t"us, eecti$e researc"$ariances Dand, t"us, eecti$e researc"
designE isdesignE is
*"e*"e MAIM+C=+MAIM+C=+-rinciple-rinciple
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Effective Research DesignEffective Research Design
+ &I-&4M&+*(J+ &I-&4M&+*(J
D"ere t"e researc"er actuallyD"ere t"e researc"er actually manipulates t"e independentmanipulates t"e independent
$ariable and measures its impact on t"e dependent $ariableE$ariable and measures its impact on t"e dependent $ariableE -roper manipulation o e:perimental conditions-roper manipulation o e:perimental conditions
to ensure "ig" $ariability in indep. $ar.to ensure "ig" $ariability in indep. $ar.
+ +=+!&I-&4M&+*AL (*H#&(J+ +=+!&I-&4M&+*AL (*H#&(J
D"ere independent and dependent $ariables are measuredD"ere independent and dependent $ariables are measuredsimultaneously and t"e relations"ip beteen t"em aresimultaneously and t"e relations"ip beteen t"em aree:aminedEe:aminedE
Appropriate subect selectionAppropriate subect selectionDselecting subectsDselecting subectst"at are suiciently dierent it" respect to t"et"at are suiciently dierent it" respect to t"e
study?s main $ar.E!!a$oidstudy?s main $ar.E!!a$oid 4ange 4estriction4ange 4estriction
M*M*imi+in( S$stematic Variance&imi+in( S$stematic Variance&
0idening t"e range o $alues0idening t"e range o $alueso researc" $ariables.o researc" $ariables.
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TypesTypes
of Descriptiveof DescriptiveResearchResearch
a.a. (ur$ey(ur$ey. A sur$ey is used "en. A sur$ey is used "ent"e obecti$es o t"e study is tot"e obecti$es o t"e study is to
see a general speciic picture osee a general speciic picture ot"e population undert"e population underin$estigation in terms o t"eirin$estigation in terms o t"eir
social and economicsocial and economicc"aracteristicsc"aracteristics
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Effective Research DesignEffective Research Design
So'rces of error variance&So'rces of error variance& -oorly designed measurement instruments-oorly designed measurement instruments
DDinstrumentation errorinstrumentation errorEE
&rror emanating rom study subects De.g.,&rror emanating rom study subects De.g.,response errorresponse errorEE
Conte:tual actorsConte:tual actorst"at reduce a soundaccuratet"at reduce a soundaccuratemeasurement instrument?s capacity to measuremeasurement instrument?s capacity to measureaccurately.accurately.
Ho, to Minimi+e Error Variance-Ho, to Minimi+e Error Variance- ncreasencrease $alidity$alidityandand reliabilityreliabilityoo
measurement instruments.measurement instruments. Measure $ariables under asMeasure $ariables under as idealideal
conditionsconditionsas possible.as possible.
MINMINimi+in( Error Varianceimi+in( Error Variance Dmeasurement errorEDmeasurement errorE Minimi;ingMinimi;ingt"e part o $ariability in scores t"at ist"e part o $ariability in scores t"at is
caused bycaused by error in measurementerror in measurement..
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1 Historical %ata on pollutionan% longevity
2 Relationship bet+een lielihoo% of
hearing problems an% high bloo% pressure
3 Recent stat sho+ in-vitroi%s are 4 times more liely to %evelop eye tumors
$Culprit! in5vitro fathers0 ol%er age&
6 #ignificantly more arme% store robberies %uring the col% +inter %ays 2626
Effective Research DesignEffective Research Design
May or may not be o primary interest to t"e researc"er,May or may not be o primary interest to t"e researc"er, But, can produceBut, can produce undesirable $ariationundesirable $ariationin t"e studyKsin t"e studyKs
dependent $ariable, and causedependent $ariable, and cause misleadingmisleadingoror eirdeirdresultsresults *"us, i not controlled,*"us, i not controlled, can contaminatedistort t"e truecan contaminatedistort t"e true
relations"ipDsErelations"ipDsEbeteen t"e independent and dependentbeteen t"e independent and dependent$ariableDsE o interest$ariableDsE o interest
i.e., conounding $ar. can result in ai.e., conounding $ar. can result in a spuriousspurious!! as opposed to!! as opposed tosubstanti$esubstanti$e!!correlation!!correlation beteen and #beteen and #.. &:ampleJ&:ampleJ
Hearing )loo%
Problem Pressure
CO7CO7trolling (ariance of Confoun%ing.7uisance (ariables!trolling (ariance of Confoun%ing.7uisance (ariables!
*IR#T, +hat are*IR#T, +hat are7uisance.Confoun%ing7uisance.Confoun%ing(ariables8(ariables8
Age
Eff ti R h D iEff ti R h D i
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Effective Research DesignEffective Research Design
Conducting t"e e:periment in aConducting t"e e:periment in a controlled en$ironmentcontrolled en$ironment De.g.,De.g.,laboratoryE, "ere e canlaboratoryE, "ere e can "old $alues"old $alueso potential conoundingo potential conounding$ariables$ariables constantconstant..
(ubect selection(ubect selectionDe.g., matc"ing subects in e:perimentsEDe.g., matc"ing subects in e:perimentsE 4andom assignment4andom assignmento subects D$ariations o conounding $ariableso subects D$ariations o conounding $ariables
are e$enly distributed beteen t"e e:perimental and control groupsEare e$enly distributed beteen t"e e:perimental and control groupsE
In Survey Resear!"In Survey Resear!" (ample selection(ample selectionDe.g., including only subects it" appropriateDe.g., including only subects it" appropriate
c"aracteristics@usingc"aracteristics@using malemalecollege graduatescollege graduatesas subects ill controlas subects ill controlor potential conounding eects o gender and educationEor potential conounding eects o gender and educationE
Statistical ControlStatistical Control!!!anticipating, measuring, and!anticipating, measuring, and statisticallystatisticallycontrolling or conounding $ariables? eectscontrolling or conounding $ariables? eectsDi.e., "old t"emDi.e., "old t"emstatistically constantstatistically constant, or statistically remo$ing t"eir eectsE., or statistically remo$ing t"eir eectsE.
HO. !O CON!ROL /OR CON/OUNDIN%0HO. !O CON!ROL /OR CON/OUNDIN%0
NUISNCE VRI1LES-NUISNCE VRI1LES-
In E#perimental SettingsIn E#perimental Settings $eg, *ertili9er "mount Rate of Plant :ro+th&$eg, *ertili9er "mount Rate of Plant :ro+th&""#ome Potential Confoun%ing (ariables8#ome Potential Confoun%ing (ariables8
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Correlational Research
in$ol$es t"e collection o to orin$ol$es t"e collection o to ormore sets o data rom a group omore sets o data rom a group o
subects it" t"e attempt tosubects it" t"e attempt todetermine t"e subse>uentdetermine t"e subse>uentrelations"ip beteen t"ose sets orelations"ip beteen t"ose sets odata.data.
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Ex 2ost /acto Research
is a systematic empirical in>uiryin "ic" t"e researc"er does not
"a$e direct control o t"eindependent $ariables.
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3)3)
Eval'ation Research
udges t"e $alue, ort" or merit
o an e:isting program. %ormati$eor summati$e e$aluation are appliedin training programs, te:tbooks,
manuals or curriculums.
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Effective Research DesignEffective Research Design
Ade>uate Dull range oE $ariability in $alues oAde>uate Dull range oE $ariability in $alues oresearc" $ariables,researc" $ariables,
-recise and accurate measurement,-recise and accurate measurement, dentiying and controlling t"e eects odentiying and controlling t"e eects o
conounding $ariables, andconounding $ariables, and Appropriate subect selectionAppropriate subect selection
4&CA-4&CA-&ecti$e researc" design is a unction o J&ecti$e researc" design is a unction o J
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BASIC DESIGNSBASIC DESIGNS
Experimental Desi(ns&Experimental Desi(ns& *rue &:perimental (tudies*rue &:perimental (tudies
-re!e:perimental (tudies-re!e:perimental (tudies
uasi!&:perimental (tudiesuasi!&:perimental (tudies
Non3Experimental Desi(ns&Non3Experimental Desi(ns&
&:post %actoCorrelational (tudies&:post %actoCorrelational (tudies
S2ECI/IC !"2ES O/ RESERCH DESI%N
BA(C 4&(&A4C' #&(G+(
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
RESUL!&RESUL!& (igniicant mpro$ement rom =1 to =2(igniicant mpro$ement rom =1 to =2Di.e., sig. =2 ! =1 dierenceEDi.e., sig. =2 ! =1 dierenceE
4UES!ION&4UES!ION& #id I Dt"e drugE cause t"e#id I Dt"e drugE cause t"eimpro$ementJimpro$ementJ
One of the simplest e;perimental %esigns is the ONE %ROU2 2RE!ES!32OS!!ES! DESI%N33E*M2LE-
One +ay to e;amine 'fficacy of a Drug!
O$ % O&
-easure DR
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
'a$e'a$e only s"ononly s"onIN is a (H%%C&+*IN is a (H%%C&+*conditionconditionor t"e c"angeor t"e c"angeONONDi.e., presence o I isDi.e., presence o I isassociated it" a c"ange in OE.associated it" a c"ange in OE.
But,But, is IN also a +&C&((A4Ois IN also a +&C&((A4Ocondition orcondition orOJOJ
'o do you $eriy t"e latterJ'o do you $eriy t"e latterJ By s"oing t"at t"e c"ange ould not "a$eBy s"oing t"at t"e c"ange ould not "a$e
"appened in t"e absence o I@using a"appened in t"e absence o I@using a
C=+*4=L G4=H-.C=+*4=L G4=H-.
'avi( Hume)oul( !ave *een tempte( to say +,ES.
He )as a positivist an( )ante( to iner ausality *ase(
on !ig! orrelations *et)een events.
/ut su! an inerene oul( *e seriously la)e(.
=hy8
Davi% Hume, 1>th
Century #cottish
Philosopher
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
C=+*4=L G4=H-C=+*4=L G4=H-simulates absence o Isimulates absence o I =rigin o using Control Groups DA tale rom=rigin o using Control Groups DA tale rom ancient &gyptEancient &gyptE
2retest 2ost3!est2retest 2ost3!est Control %ro'pControl %ro'pDesi(n33Desi(n33(uppose random(uppose random
assignment Dassignment DRRE as used to control conounding $ariablesE as used to control conounding $ariables
RR Exp5 %ro'p O6E * O7EExp5 %ro'p O6E * O7E
RR Ctrl %ro'p O6C O7C Ctrl %ro'p O6C O7C
RESUL!&RESUL!& =2& P =1& =2C +otP =1C=2& P =1& =2C +otP =1C4UES!ION&4UES!ION& #id I cause t"e impro$ement in &:p.#id I cause t"e impro$ement in &:p.
GroupJGroupJ
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
+eed+eed proper orm o controlproper orm o [email protected].,@e.g., -lacebo-lacebo..
RR Exp5 %ro'p O6E * O7EExp5 %ro'p O6E * O7E RR Ctrl %ro'p O6C 2lace8o O7CCtrl %ro'p O6C 2lace8o O7C
4UES!ION&4UES!ION& Can e no conclude I caused t"e impro$ementCan e no conclude I caused t"e impro$ementin &:p. GroupJin &:p. GroupJ
0OT 0ECESSARIL,1 2!y not3?Po+er of suggestibility $The Ha+thorne 'ffect&
CO7C@
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
Experimental st'diesExperimental st'dies need toneed to controlcontrolforfor potentialpotentialconfo'ndin( factorsconfo'ndin( factorsthat ma$ threaten internal validit$that ma$ threaten internal validit$of the experiment&of the experiment&
Ha,thorne EffectHa,thorne Effect is only one potential conounding actoris only one potential conounding actorin e:perimental studies.in e:perimental studies.
=t"er suc" actors are=t"er suc" actors are
Histor$-Histor$- Biasing e$ents t"at occur beteen pretest and post!testBiasing e$ents t"at occur beteen pretest and post!test
Mat'ration-Mat'ration- -"ysicalbiologicalpsyc"ological c"anges in t"e subects-"ysicalbiologicalpsyc"ological c"anges in t"e subects
!estin(-!estin(- &:posure to pretest inluences scores on post!test&:posure to pretest inluences scores on post!test
Instr'mentation-Instr'mentation- %las in measurement instrumentprocedure%las in measurement instrumentprocedure
EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
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EXERIMENTA! DESIGNSEXERIMENTA! DESIGNS
Experimental st'diesExperimental st'diesneed toneed to controlcontrolforfor potentialpotentialconfo'ndin( factorsconfo'ndin( factorsthat ma$ threaten internal validit$that ma$ threaten internal validit$
of the experiment 9Contin'ed#&of the experiment 9Contin'ed#&
Selection-Selection- (ubects in e:perimental control groups dierent rom t"e start(ubects in e:perimental control groups dierent rom t"e start
Statistical Re(ression 9re(ression to,ard the mean#-Statistical Re(ression 9re(ression to,ard the mean#- (ubects selected based on e:treme pretest $alues(ubects selected based on e:treme pretest $alues #isco$ered by#isco$ered by %rancis Galton%rancis Galtonin 1877in 1877
Experimental Mortalit$-Experimental Mortalit$-
#ierential drop!out o subects rom e:perimental and control#ierential drop!out o subects rom e:perimental and controlgroups during t"e studygroups during t"e study
EtcEtc..&:perimental designs mostly used in&:perimental designs mostly used in natural and p"ysicalnatural and p"ysical
sciencessciences..
Generally, "ig"er internal $alidity, loer e:ternalGenerally, "ig"er internal $alidity, loer e:ternal$alidity$alidity
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C"RRE!ATI"NA! DESIGNSC"RRE!ATI"NA! DESIGNS
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C"RRE!ATI"NA! DESIGNSC"RRE!ATI"NA! DESIGNS
*"e design o c"oice in*"e design o c"oice in social sciencessocial sciencessince t"esince t"e p"enomenonp"enomenon
under study is usuallyunder study is usually not reproducible in a laboratory settingnot reproducible in a laboratory setting
4esearc"er "as4esearc"er "as little or no controllittle or no controlo$er study?s indep., dep.o$er study?s indep., dep.and t"eand t"e numerous potentialnumerous potential conounding $ariablesconounding $ariables,,
=ten t"e researc"er=ten t"e researc"er
concomitantly measuresconcomitantly measures
all t"e studyall t"e study
$ariables De.g., independent, dependant, etc.E,$ariables De.g., independent, dependant, etc.E,
*"en e:amines t"e olloing types o relations"ips*"en e:amines t"e olloing types o relations"ips correlations among $ariablescorrelations among $ariablesoror
dierences among groupsdierences among groups,,
nability to controlnability to controlor eects oor eects o conounding $ariablesconounding $ariables makesmakescausal inerencescausal inerencesregarding relations"ips among $ariablesregarding relations"ips among $ariablesmore diicultmore diicultand, t"usand, t"us
Generally, "ig"er e:ternal $alidity, loer internal $alidityGenerally, "ig"er e:ternal $alidity, loer internal $alidity
NON3E*2ERIMEN!L0CORREL!IONL DESI%NSNON3E*2ERIMEN!L0CORREL!IONL DESI%NS
C"RRE!ATI"NA! DESIGNSC"RRE!ATI"NA! DESIGNS
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C"RRE!ATI"NA! DESIGNSC"RRE!ATI"NA! DESIGNS
NO! NECESSRIL": E*M2LES&NO! NECESSRIL": E*M2LES&
.ater /l'oridation and IDS.ater /l'oridation and IDS
99San Francisco ChronicleSan Francisco Chronicle; Sep5 ?#; Sep5 ?#
rmed store ro88eries and cold ,eatherrmed store ro88eries and cold ,eather
Lon(evit$ and 2oll'tionLon(evit$ and 2oll'tion
In3vitro 8irth and li@elihood of developin( e$eIn3vitro 8irth and li@elihood of developin( e$et'morst'mors
Hearin( pro8lem and 8lood press'reHearin( pro8lem and 8lood press're
.hat can a si(nificant correlation mean then-.hat can a si(nificant correlation mean then-
7on5e;perimental %esigns rely on correlational evi%ence
65ESTIO0" Does a significant correlation bet+een t+o
variables in a non5e;perimental stu%y necessarily represent a
causal relationship bet+een those variables8
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C"RRE!ATI"NA! ST#DIESC"RRE!ATI"NA! ST#DIES
a.a. Bot" $ariables are eects o a common cause DorBot" $ariables are eects o a common cause Dor bot"bot"correlated it" a t"ird $ariableE, i.e., spurious correlationcorrelated it" a t"ird $ariableE, i.e., spurious correlationDe.g., air pollution and lie e:pectancy, "earing problem De.g., air pollution and lie e:pectancy, "earing problem blood pressure, country?s annual ice cream sales andblood pressure, country?s annual ice cream sales andre>uency o "ospital admissions or "eat strokeEre>uency o "ospital admissions or "eat strokeE
b.b. Bot" $ar.Bot" $ar. alternati$e indicatorsalternati$e indicatorso same concepto same conceptDe.g., C"urc" attend. %re>. o -raying!!religiosityE.De.g., C"urc" attend. %re>. o -raying!!religiosityE.
c.c. Bot" parts oBot" parts o a common QsystemQ or Qcomple:RQ tend toa common QsystemQ or Qcomple:RQ tend tocome as a packagecome as a packageDe.g., martini drinking and opera attendance!!lie styleEDe.g., martini drinking and opera attendance!!lie styleE
d.d. %ortuitous!!%ortuitous!!Coincidental correlationCoincidental correlation, no logical relations"ip, no logical relations"ip
De.g., =utcome o super bol games and mo$ement o stockDe.g., =utcome o super bol games and mo$ement o stockmarketEmarketE
AT LEAST FO5R OTHER POSSI/LE I0TERPRETATIO0S7REASO0S
FOR CORRELATIO0S /ET2EE0 T2O 8ARIA/LES"
C"RRE!ATI"NA! ST#DIESC"RRE!ATI"NA! ST#DIES
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C"RRE!ATI"NA! ST#DIESC"RRE!ATI"NA! ST#DIES
Covariation R'leCovariation R'leDI and O must beDI and O must becorrelatedE!!+ecessary but not suicient condition.correlatedE!!+ecessary but not suicient condition.
!emporal 2recedence R'le!emporal 2recedence R'leD I is t"e cause, OD I is t"e cause, Os"ould not occur until ater IE.s"ould not occur until ater IE.
Internal Validit$ R'leInternal Validit$ R'leDAlternati$e plausibleDAlternati$e plausiblee:planations o O and I!O relations"ips s"ould bee:planations o O and I!O relations"ips s"ould beruled out Di.e., eliminate ot"er possible causesE.ruled out Di.e., eliminate ot"er possible causesE.
n practice, t"is means e:ercising caution byn practice, t"is means e:ercising caution byidentiying potentialidentiying potential conounding $ariables andconounding $ariables and
2HE0 IS IT SAFER TO I0FER CA5SAL
LI09A:ES FROM STRO0: CORRELATIO0S3;o!n Stuart Mill