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Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
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CaseSelectionforCase‐ StudyAnalysis:QualitativeandQuantitative
Techniques JohnGerring
TheOxfordHandbookofPoliticalMethodology
EditedbyJanetM.Box-Steffensmeier,HenryE.Brady,andDavidCollier
PrintPublicationDate: Aug2008
OnlinePublicationDate: Sep
2009
Subject: PoliticalScience,ComparativePolitics,Political
Methodology
DOI: 10.1093/oxfordhb/9780199286546.003.0028
AbstractandKeywords
Thisarticlepresentssomeguidancebycatalogingninedifferenttechniquesforcaseselection:typical,diverse,
extreme,deviant,influential,crucial,pathway,mostsimilar,andmostdifferent.Italsoindicatesthatifthe
researcherisstartingfromaquantitativedatabase,thenmethodsforfindinginfluentialoutlierscanbeused.In
particular,thearticleclarifiesthegeneralprinciplesthatmightguidetheprocessofcaseselectionincase-study
research.Casesaremoreorlessrepresentativeofsomebroaderphenomenonand,onthatscore,maybe
consideredbetterorworsesubjectsforintensiveanalysis.Thearticlethendrawsattentiontotwoambiguitiesin
case-selectionstrategiesincase-studyresearch.Thefirstconcernstheadmixtureofseveralcase-selection
strategies.Thesecondconcernsthechangingstatusofacaseasastudyproceeds.Somecasestudiesfollow
onlyonestrategyofcaseselection.
Keywords:typicalcase,diversecase,extremecase,deviantcase,influentialcase,crucialcase,pathwaycase,mostsimilarcase,mostdifferent
case,case-studyanalysis
CASE ‐studyanalysisfocusesononeorseveralcasesthatareexpectedtoprovideinsightintoalargerpopulation.
Thispresentstheresearcherwithaformidableproblemofcaseselection:Whichcasesshouldsheorhechoose?
Inlarge‐sampleresearch,thetaskofcaseselectionisusuallyhandledbysomeversionofrandomization.
However,incase‐studyresearchthesampleissmall(bydefinition)andthismakesrandomsamplingproblematic,
foranygivensamplemaybewildlyunrepresentative.Moreover,thereisnoguaranteethatafewcases,chosen
randomly,willprovideleverageintotheresearchquestionofinterest.
Inordertoisolateasampleofcasesthatbothreproducestherelevantcausalfeaturesofalargeruniverse
(representativeness)andprovidesvariationalongthedimensionsoftheoreticalinterest(causalleverage),case
selectionforverysmallsamplesmustemploypurposive(nonrandom)selectionprocedures.Ninesuchmethods
arediscussedinthischapter,eachofwhichmaybeidentifiedwithadistinctcase‐study(p.646) “type:”typical,
diverse,extreme,deviant,influential,crucial,pathway,most‐similar,andmost‐different.Table28.1summarizes
eachtype,includingitsgeneraldefinition,atechniqueforlocatingitwithinapopulationofpotentialcases,itsuses,
anditsprobablerepresentativeness.
Whileeachofthesetechniquesisnormallypracticedononeorseveralcases(thediverse,most‐similar,andmost‐
differentmethodsrequireatleasttwo),allmayemployadditionalcases—withtheprovisothat,atsomepoint,they
willnolongerofferanopportunityforin‐depthanalysisandwillthusnolongerbe“casestudies”intheusualsense
(Gerring2007,ch.2).Itwillalsobeseenthatsmall‐Ncase‐selectionproceduresrest,atleastimplicitly,uponan
analysisofalargerpopulationofpotentialcases(asdoesrandomization).Thecase(s)identifiedforintensive
studyischosenfromapopulationandthereasonsforthischoicehingeuponthewayinwhichitissituatedwithin
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Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
thatpopulation.Thisistheoriginoftheterminology—typical,diverse,extreme,etal.Itfollowsthatcase‐selection
proceduresincase‐studyresearchmaybuilduponpriorcross‐caseanalysisandthattheydepend,atthevery
least,uponcertainassumptionsaboutthebroaderpopulation.
Incertaincircumstances,thecase‐selectionproceduremaybestructuredbyaquantitativeanalysisofthelarger
population.Here,severalcaveatsmustbesatisfied.First,theinferencemustpertaintomorethanafewdozen
cases;otherwise,statisticalanalysisisproblematic.Second,relevantdatamustbeavailableforthatpopulation,or
asignificantsampleofthatpopulation,onkeyvariables,andtheresearchermustfeelreasonablyconfidentinthe
accuracyandconceptualvalidityofthesevariables.Third,allthestandardassumptionsofstatisticalresearch
(e.g.identification,specification,robustness)mustbecarefullyconsidered,andwhereverpossible,tested.Ishall
notdilatefurtheronthesefamiliarissuesexcepttowarntheresearcheragainsttheunreflectiveuseofstatistical
techniques.1Whentheserequirementsarenotmet,theresearchermustemployaqualitativeapproachtocase
selection.
Thepointofthischapteristoelucidategeneralprinciplesthatmightguidetheprocessofcaseselectionincase‐
studyresearch,buildinguponearlierworkbyHarryEckstein,ArendLijphart,andothers.Sometimes,these
principlescanbeappliedinaquantitativeframeworkandsometimestheyarelimitedtoaqualitativeframework.In
eithercase,thelogicofcaseselectionremainsquitesimilar,whetherpracticedinsmall‐Norlarge‐Ncontexts.
Beforewebegin,abitofnotationisnecessary.Inthischapter“N”referstocases,notobservations.Here,Iam
concernedprimarilywithcausalinference,ratherthaninferencesthataredescriptiveorpredictiveinnature.Thus,
allhypothesesinvolveatleastoneindependentvariable(X)andonedependentvariable(Y).Forconvenience,I
shalllabelthecausalfactorofspecialtheoreticalinterestX1,andthecontrolvariable,orvectorofcontrols(if
thereareany),X2 .Ifthewriterisconcernedtoexplainapuzzlingoutcome,buthasnopreconceptionsaboutits
causes,thentheresearchwillbedescribedasY‐centered.Ifaresearcherisconcernedto(p.647) (p.648)
investigatetheeffectsofaparticularcause,withnopreconceptionsaboutwhattheseeffectsmightbe,the
researchwillbedescribedasX‐centered.Ifaresearcherisconcernedtoinvestigateaparticularcausal
relationship,theresearchwillbedescribedasX1/Y‐centered,foritconnectsaparticularcausewithaparticular
outcome.2 X‐orY‐centeredresearchisexploratory;itspurposeistogeneratenewhypotheses.X1/Y‐centered
research,bycontrast,isconfirmatory/disconfirmatory;itspurposeistotestanexistinghypothesis.
Table28.1.Techniquesofcaseselection
1.Typical
ºDefinition:Cases(1ormore)aretypicalexamplesofsomecross‐caserelationship.
ºCross‐casetechnique:Alow‐residualcase(on‐lier).
ºUses:Hypothesis‐testing.
ºRepresentativeness:Bydefinition,thetypicalcaseisrepresentative.
2.Diverse
ºDefinition:Cases(2ormore)illuminatethefullrangeofvariationonX1,,Y,orX1/Y.
ºCross‐casetechnique:Diversitymaybecalculatedby(a)categoricalvaluesofX1orY(e.g.Jewish,
Catholic,Protestant),(b)standarddeviationsofX1orY(ifcontinuous),(c)combinationsofvalues(e.g.based
oncross‐tabulations,factoranalysis,ordiscriminantanalysis).
ºUses:Hypothesisgeneratingorhypothesistesting.
ºRepresentativeness:Diversecasesarelikelytoberepresentativeintheminimalsenseofrepresentingthe
fullvariationofthepopulation(thoughtheymightnotmirrorthedistributionofthatvariationinthepopulation).
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Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
fullvariationofthepopulation(thoughtheymightnotmirrorthedistributionofthatvariationinthepopulation).
3.Extreme
ºDefinition:Cases(1ormore)exemplifyextremeorunusualvaluesofX1orYrelativetosomeunivariate
distribution.
ºCross‐casetechnique:AcaselyingmanystandarddeviationsawayfromthemeanofX1orY.
ºUses:Hypothesis‐generating(open‐endedprobeofX1orY).
ºRepresentativeness:Achievableonlyincomparisonwithalargersampleofcases.
4.Deviant
ºDefinition:Cases(1ormore)deviatefromsomecross‐caserelationship.
ºCross‐casetechnique:Ahigh‐residualcase(outlier).
ºUses:Hypothesis‐generating(todevelopnewexplanationsforY).
ºRepresentativeness:Afterthecasestudyisconducteditmaybecorroboratedbyacross‐casetest,which
includesageneralhypothesis(anewvariable)basedonthecase‐studyresearch.Ifthecaseisnowanon‐
lier,itmaybeconsideredrepresentativeofthenewrelationship.
5.Influential
ºDefinition:Cases(1ormore)withinfluentialconfigurationsoftheindependentvariables.
ºCross‐casetechnique:HatmatrixorCook'sDistance.
ºUses:Hypothesis‐testing(toverifythestatusofcasesthatmayinfluencetheresultsofacross‐case
analysis).
ºRepresentativeness:Notpertinent,giventhegoalsoftheinfluential‐casestudy.
6.Crucial
ºDefinition:Cases(1ormore)aremostorleastlikelytoexhibitagivenoutcome.
ºCross‐casetechnique:Qualitativeassessmentofrelativecrucialness.
ºUses:Hypothesis‐testing(confirmatoryordisconfirmatory).
ºRepresentativeness:Oftendifficulttoassess.
7.Pathway
ºDefinition:Cases(1ormore)thatembodyadistinctcausalpathfromX1toY.
ºCross‐casetechnique:Cross‐tab(forcategoricalvariables)orresidualanalysis(forcontinuousvariables).
ºUses:Hypothesis‐testing(toprobecausalmechanisms).
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Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
ºRepresentativeness:Maybetestedbyexaminingresidualsforthechosencases.
8.Most‐similar
ºDefinition/:Cases(2ormore)aresimilaronspecifiedvariablesotherthanX/1/and/orY.
ºCross‐casetechnique:Matching.
ºUses:Hypothesis‐generatingorhypothesis‐testing.
ºRepresentativeness:Maybetestedbyexaminingresidualsforthechosencases.
9.Most‐different
ºDefinition:Cases(2ormore)aredifferentonspecifiedvariablesotherthanX1andY.
ºCross‐casetechnique:Theinverseofthemost‐similarmethodoflarge‐Ncaseselection(seeabove).
ºUses:Hypothesis‐generatingorhypothesis‐testing(eliminatingdeterministiccauses).
ºRepresentativeness:Maybetestedbyexaminingresidualsforthechosencases.
1TypicalCase
Inorderforafocusedcasestudytoprovideinsightintoabroaderphenomenonitmustberepresentativeofa
broadersetofcases.Itisinthiscontextthatonemayspeakofatypical‐caseapproachtocaseselection.The
typicalcaseexemplifieswhatisconsideredtobeatypicalsetofvalues,givensomegeneralunderstandingofa
phenomenon.Byconstruction,thetypicalcaseisalsoarepresentativecase.
Sometypicalcasesserveanexploratoryrole.Here,theauthorchoosesacasebaseduponasetofdescriptive
characteristicsandthenprobesforcausalrelationships.RobertandHelenLynd(1929/1956)selectedasinglecity
“tobeasrepresentativeaspossibleofcontemporaryAmericanlife.”Specifically,theywerelookingforacitywith
1)atemperateclimate;2)asufficientlyrapidrateofgrowthtoensurethepresenceofaplentiful
assortmentofthegrowingpainsaccompanyingcontemporarysocialchange;3)anindustrialculturewith
modern,high‐speedmachineproduction;4)theabsenceofdominanceofthecity'sindustrybyasingle
plant(i.e.,notaone‐industrytown);5)asubstantiallocalartistic(p.649) lifetobalanceitsindustrial
activity…;and6)theabsenceofanyoutstandingpeculiaritiesoracutelocalproblemswhichwouldmark
thecityofffromthemidchannelsortofAmericancommunity.(LyndandLynd1929/1956,quotedinYin
2004,29–30)
AfterexamininganumberofoptionstheLyndsdecidedthatMuncie,Indiana,wasmorerepresentativethan,orat
leastasrepresentativeas,othermidsizedcitiesinAmerica,thusqualifyingasatypicalcase.
Thisisaninductiveapproachtocaseselection.Notethattypicalitymaybeunderstoodaccordingtothemean,
median,ormodeonaparticulardimension;theremaybemultipledimensions(asintheforegoingexample);and
eachmaybedifferentlyweighted(somedimensionsmaybemoreimportantthanothers).Wheretheselection
criteriaaremultidimensionalandalargesampleofpotentialcasesisinplay,someformoffactoranalysismaybe
usefulinidentifyingthemost‐typicalcase(s).
However,themorecommonemploymentofthetypical‐casemethodinvolvesacausalmodelofsomephenomenon
oftheoreticalinterest.Here,theresearcherhasidentifiedaparticularoutcome(Y),andperhapsaspecificX1/Y
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Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
hypothesis,whichshewishestoinvestigate.Inordertodoso,shelooksforatypicalexampleofthatcausal
relationship.Intuitively,oneimaginesthatacaseselectedaccordingtothemeanvaluesofallparametersmustbe
atypicalcaserelativetosomecausalrelationship.However,thisisbynomeansassured.
SupposethattheLyndswereprimarilyinterestedinexplainingfeelingsoftrust/distrustamongmembersofdifferent
socialclasses(oneoftheimplicitresearchgoalsoftheMiddletownstudy).Thisoutcomeislikelytobeaffectedby
manyfactors,onlysomeofwhichareincludedintheirsixselectioncriteria.Sochoosingcaseswithrespecttoa
causalhypothesisinvolves,firstofall,identifyingtherelevantparameters.Itinvolves,secondly,theselectionofa
casethathasa“typical”valuerelativetotheoverallcausalmodel;itiswellexplained.Caseswithuntypical
scoresonaparticulardimension(e.g.veryhighorverylow)maystillbetypicalexamplesofacausalrelationship.
Indeed,theymaybemoretypicalthancaseswhosevalueslieclosetothemean.Thus,adescriptive
understandingoftypicalityisquitedifferentfromacausalunderstandingoftypicality.Sinceitisthelatterversion
thatismorecommon,Ishalladoptthisunderstandingoftypicalityintheremainderofthediscussion.
Fromaqualitativeperspective,causaltypicalityinvolvestheselectionofacasethatconformstoexpectations
aboutsomegeneralcausalrelationship.Itperformsasexpected.Inaquantitativesetting,thisnotionismeasured
bythesizeofacase'sresidualinalarge‐Ncross‐casemodel.Typicalcaseslieonorneartheregressionline;
theirresidualsaresmall.Insofarasthemodeliscorrectlyspecified,thesizeofacase'sresidual(i.e.thenumberof
standarddeviationsthatseparatetheactualvaluefromthefittedvalue)providesahelpfulcluetohow
representativethatcaseislikelytobe.“Outliers”areunlikelytoberepresentativeofthetargetpopulation.
Ofcourse,justbecauseacasehasalowresidualdoesnotnecessarilymeanthatitisarepresentativecase(with
respecttothecausalrelationshipofinterest).Indeed,(p.650) theissueofcaserepresentativenessisanissue
thatcanneverbedefinitivelysettled.Whenonereferstoa“typicalcase”oneissaying,ineffect,thatthe
probabilityofacase'srepresentativenessishigh,relativetoothercases.Thistestoftypicalityismisleadingifthe
statisticalmodelismis‐specified.Anditprovideslittleinsuranceagainsterrorsthatarepurelystochastic.Acase
mayliedirectlyontheregressionlinebutstillbe,insomeimportantrespect,atypical.Forexample,itmighthavean
oddcombinationofvalues;theinteractionofvariablesmightbedifferentfromothercases;oradditionalcausal
mechanismsmightbeatwork.Forthisreason,itisimportanttosupplementastatisticalanalysisofcaseswith
evidencedrawnfromthecaseinquestion(thecasestudyitself)andwithourdeductiveknowledgeoftheworld.
Oneshouldneverjudgeacasesolelybyitsresidual.Yet,allotherthingsbeingequal,acasewithalowresidualis
lesslikelytobeunusualthanacasewithahighresidual,andtothisextentthemethodofcaseselectionoutlined
heremaybeahelpfulguidetocase‐studyresearchersfacedwithalargenumberofpotentialcases.
Bywayofconclusion,itshouldbenotedthatbecausethetypicalcaseembodiesatypicalvalueonsomesetof
causallyrelevantdimensions,thevarianceofinteresttotheresearchermustliewithinthatcase.Specifically,the
typicalcaseofsomephenomenonmaybehelpfulinexploringcausalmechanismsandinsolvingidentification
problems(e.g.endogeneitybetweenX1andY,anomittedvariablethatmayaccountforX1andY,orsomeother
spuriouscausalassociation).Dependingupontheresultsofthecasestudy,theauthormayconfirmanexisting
hypothesis,disconfirmthathypothesis,orreframeitinawaythatisconsistentwiththefindingsofthecasestudy.
Thesearetheusesofthetypical‐casestudy.
2DiverseCases
Asecondcase‐selectionstrategyhasasitsprimaryobjectivetheachievementofmaximumvariancealong
relevantdimensions.Irefertothisasadiverse‐casemethod.Forobviousreasons,thismethodrequiresthe
selectionofasetofcases—atminimum,two—whichareintendedtorepresentthefullrangeofvalues
characterizingX1,Y,orsomeparticularX1/Yrelationship.3
Wheretheindividualvariableofinterestiscategorical(on/off,red/black/blue,Jewish/Protestant/Catholic),the
identificationofdiversityisreadilyapparent.Theinvestigatorsimplychoosesonecasefromeachcategory.Fora
continuousvariable,(p.651) thechoicesarenotsoobvious.However,theresearcherusuallychoosesboth
extremevalues(highandlow),andperhapsthemeanormedianaswell.Theresearchermayalsolookforbreak‐
pointsinthedistributionthatseemtocorrespondtocategoricaldifferencesamongcases.Orshemayfollowa
theoreticalhunchaboutwhichthresholdvaluescount,i.e.whicharelikelytoproducedifferentvaluesonY.
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Anothersortofdiversecasetakesaccountofthevaluesofmultiplevariables(i.e.avector),ratherthanasingle
variable.Ifthesevariablesarecategorical,theidentificationofcausaltypesrestsupontheintersectionofeach
category.Twodichotomousvariablesproduceamatrixwithfourcells.Threetrichotomousvariablesproducea
matrixofeightcells.Andsoforth.Ifallvariablesaredeemedrelevanttotheanalysis,theselectionofdiverse
casesmandatestheselectionofonecasedrawnfromwithineachcell.Letussaythatanoutcomeisthoughttobe
affectedbysex,race(black/white),andmaritalstatus.Here,adiverse‐casestrategyofcaseselectionwould
identifyonecasewithineachoftheseintersectingcells—atotalofeightcases.Thingsbecomeslightlymore
complicatedwhenoneormoreofthefactorsiscontinuous,ratherthancategorical.Here,thediversityofcase
valuesdonotfallneatlyintocells.Rather,thesecellsmustbecreatedbyfiat—e.g.high,medium,low.
Itwillbeseenthatwheremultiplevariablesareunderconsideration,thelogicofdiverse‐caseanalysisrestsupon
thelogicoftypologicaltheorizing—wheredifferentcombinationsofvariablesareassumedtohaveeffectsonan
outcomethatvaryacrosstypes(Elman2005;GeorgeandBennett2005,235;LazarsfeldandBarton1951).George
andSmoke,forexample,wishtoexploredifferenttypesofdeterrencefailure—by“faitaccompli,”by“limited
probe,”andby“controlledpressure.”Consequently,theywishtofindcasesthatexemplifyeachtypeofcausal
mechanism.4
DiversitymaythusrefertoarangeofvariationonXorY,ortoaparticularcombinationofcausalfactors(withor
withoutaconsiderationoftheoutcome).Ineachinstance,thegoalofcaseselectionistocapturethefullrangeof
variationalongthedimension(s)ofinterest.
Sincediversitycanmeanmanythings,itsemploymentinalarge‐Nsettingisnecessarilydependentuponhowthis
keytermisdefined.Ifitisunderstoodtopertainonlytoasinglevariable(X1orY),thenthetaskisfairlysimple.A
categoricalvariablemandatesthechoiceofatleastonecasefromeachcategory—twoifdichotomous,threeif
trichotomous,andsoforth.Acontinuousvariablesuggeststhechoiceofatleastone“high”and“low”value,and
perhapsonedrawnfromthemeanormedian.Butotherchoicesmightalsobejustified,accordingtoone'shunch
abouttheunderlyingcausalrelationshiporaccordingtonaturalthresholdsfoundinthedata,whichmaybe
groupedintodiscretecategories.Single‐variabletraitsareusuallyeasytodiscoverinalarge‐Nsettingthrough
descriptivestatisticsorthroughvisualinspectionofthedata.
(p.652) Wherediversityreferstoparticularcombinationsofvariables,therelevantcross‐casetechniqueis
someversionofstratifiedrandomsampling(inaprobabilisticsetting)orQualitativeComparativeAnalysis(ina
deterministicsetting)(Ragin2000).Iftheresearchersuspectsthatacausalrelationshipisaffectednotonlyby
combinationsoffactorsbutalsobytheirsequencing,thenthetechniqueofanalysismustincorporatetemporal
elements(Abbott2001;AbbottandForrest1986;AbbottandTsay2000).Thus,themethodofidentifyingcausal
typesrestsuponwhatevermethodofidentifyingcausalrelationshipsisemployedinthelarge‐Nsample.
Notethattheidentificationofdistinctcasetypesisintendedtoidentifygroupsofcasesthatareinternally
homogeneous(inallrespectsthatmightaffectthecausalrelationshipofinterest).Thus,thechoiceofcaseswithin
eachgroupshouldnotbeproblematic,andmaybeaccomplishedthroughrandomsamplingorpurposivecase
selection.However,ifthereissuspecteddiversitywithineachcategory,thenmeasuresshouldbetakentoassure
thatthechosencasesaretypicalofeachcategory.Acasestudyshouldnotfocusonanatypicalmemberofa
subgroup.
Indeed,considerationsofdiversityandtypicalityoftengotogether.Thus,inastudyofglobalizationandsocial
welfaresystems,DuaneSwank(2002)firstidentifiesthreedistinctivegroupsofwelfarestates:“universalistic”
(socialdemocratic),“corporatistconservative,”and“liberal.”Next,helookswithineachgrouptofindthemost‐
typicalcases.HedecidesthattheNordiccountriesaremoretypicaloftheuniversalisticmodelthanthe
Netherlandssincethelatterhas“somecharacteristicsoftheoccupationallybasedprogramstructureanda
politicalcontextofChristianDemocratic‐ledgovernmentstypicalofthecorporatistconservativenations”(Swank
2002,11;seealsoEsping‐Andersen1990).Thus,theNordiccountriesarechosenasrepresentativecaseswithin
theuniversalisticcasetype,andareaccompaniedinthecase‐studyportionofhisanalysisbyothercaseschosen
torepresenttheotherwelfarestatetypes(corporatistconservativeandliberal).
Evidently,whenasampleencompassesafullrangeofvariationonrelevantparametersoneislikelytoenhance
therepresentativenessofthatsample(relativetosomepopulation).Thisisadistinctadvantage.Ofcourse,the
inclusionofafullrangeofvariationmaydistorttheactualdistributionofcasesacrossthisspectrum.Ifthereare
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more“high”casesthan“low”casesinapopulationandtheresearcherchoosesonlyonehighcaseandonelow
case,theresultingsampleoftwoisnotperfectlyrepresentative.Evenso,thediverse‐casemethodprobablyhas
strongerclaimstorepresentativenessthananyothersmall‐Nsample(includingthestandalonetypicalcase).The
selectionofdiversecaseshastheadditionaladvantageofintroducingvariationonthekeyvariablesofinterest.A
setofdiversecasesis,bydefinition,asetofcasesthatencompassesarangeofhighandlowvaluesonrelevant
dimensions.Thereis,therefore,muchtorecommendthismethodofcaseselection.Isuspectthatthese
advantagesarecommonlyunderstoodandareappliedonanintuitivelevelbycase‐studyresearchers.However,
thelackofarecognizablename—andanexplicitmethodologicaldefense—hasmadeitdifficultforcase‐study
researcherstoutilizethismethodofcaseselection,andtodosoinanexplicitandself‐consciousfashion.
Neologismhasitsuses.
(p.653) 3ExtremeCase
Theextreme‐casemethodselectsacasebecauseofitsextremevalueonanindependent(X1)ordependent(Y)
variableofinterest.Thus,studiesofdomesticviolencemaychoosetofocusonextremeinstancesofabuse
(Browne1987).Studiesofaltruismmayfocusonthoserareindividualswhoriskedtheirlivestohelpothers(e.g.
Holocaustresisters)(Monroe1996).Studiesofethnicpoliticsmayfocusonthemostheterogeneoussocieties(e.g.
PapuaNewGuinea)inordertobetterunderstandtheroleofethnicityinademocraticsetting(Reilly2000–1).
Studiesofindustrialpolicyoftenfocusonthemostsuccessfulcountries(i.e.theNICS)(Deyo1987).Andsoforth.5
Oftenanextremecasecorrespondstoacasethatisconsideredtobeprototypicalorparadigmaticofsome
phenomenaofinterest.Thisisbecauseconceptsareoftendefinedbytheirextremes,i.e.theiridealtypes.Italian
FascismdefinestheconceptofFascism,inpart,becauseitofferedthemostextremeexampleofthatphenomenon.
However,themethodologicalvalueofthiscase,andotherslikeit,derivesfromitsextremity(alongsome
dimensionofinterest),notitstheoreticalstatusoritsstatusintheliteratureonasubject.
Thenotionof“extreme”maynowbedefinedmoreprecisely.Anextremevalueisanobservationthatliesfaraway
fromthemeanofagivendistribution.Thismaybemeasured(iftherearesufficientobservations)byacase's“Z
score”—thenumberofstandarddeviationsbetweenacaseandthemeanvalueforthatsample.Extremecases
havehighZscores,andforthisreasonmayserveasusefulsubjectsforintensiveanalysis.
Foracontinuousvariable,thedistancefromthemeanmaybeineitherdirection(positiveornegative).Fora
dichotomousvariable(present/absent),extremenessmaybeinterpretedasunusual.Ifmostcasesarepositive
alongagivendimension,thenanegativecaseconstitutesanextremecase.Ifmostcasesarenegative,thena
positivecaseconstitutesanextremecase.Itshouldbeclearthatresearchersarenotsimplyconcernedwith
caseswheresomething“happened,”butalsowithcaseswheresomethingdidnot.Itistherarenessofthevalue
thatmakesacasevaluable,inthiscontext,notitspositiveornegativevalue.6 Thus,ifoneisstudyingstate
capacity,acaseofstatefailureisprobablymoreinformativethanacaseofstateendurancesimplybecausethe
formerismoreunusual.Similarly,ifoneisinterestedinincesttaboosaculturewheretheincesttabooisabsentor
weakisprobablymoreusefulthanaculturewhereitispresentorstrong.Fascismismoreimportantthan
nonfascism.Andsoforth.Thereisagoodreason,therefore,whycasestudiesofrevolutiontendtofocuson
“revolutionary”cases.ThedaSkocpol(1979)hadmuchmoretolearnfromFrancethanfromAustro‐Hungarysince
FrancewasmoreunusualthanAustro‐HungarywithinthepopulationofnationstatesthatSkocpolwas(p.654)
concernedtoexplain.Thereasonisquitesimple:Therearefewerrevolutionarycasesthannonrevolutionary
cases;thus,thevariationthatweexploreasacluetocausalrelationshipsisencapsulatedinthesecases,against
abackgroundofnonrevolutionarycases.
Notethattheextreme‐casemethodofcaseselectionappearstoviolatethesocialsciencefolkwisdomwarningus
notto“selectonthedependentvariable.”7 Selectingcasesonthedependentvariableisindeedproblematicifa
numberofcasesarechosen,allofwhichlieononeendofavariable'sspectrum(theyareallpositiveornegative),
andiftheresearcherthensubjectsthissampletocross‐caseanalysisasifitwererepresentativeofapopulation.8
Resultsforthissortofanalysiswouldalmostassuredlybebiased.Moreover,therewillbelittlevariationtoexplain
sincethevaluesofeachcaseareexplicitlyconstrained.
However,thisisnottheproperemploymentoftheextreme‐casemethod.(Itismoreappropriatelylabeledan
extreme‐samplemethod.)Theextreme‐casemethodactuallyrefersbacktoalargersampleofcasesthatlieinthe
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backgroundoftheanalysisandprovideafullrangeofvariationaswellasamorerepresentativepictureofthe
population.Itisaself‐consciousattempttomaximizevarianceonthedimensionofinterest,nottominimizeit.If
thispopulationofcasesiswellunderstood—eitherthroughtheauthor'sowncross‐caseanalysis,throughthework
ofothers,orthroughcommonsense—thenaresearchermayjustifytheselectionofasinglecaseexemplifyingan
extremevalueforwithin‐caseanalysis.Ifnot,theresearchermaybewelladvisedtofollowadiverse‐casemethod,
asdiscussedabove.
Bywayofconclusion,letusreturntotheproblemofrepresentativeness.Itwillbeseenthatanextremecasemay
betypicalordeviant.ThereissimplynowaytotellbecausetheresearcherhasnotyetspecifiedanX1/Ycausal
proposition.Oncesuchacausalpropositionhasbeenspecifiedonemaythenaskwhetherthecaseinquestionis
similartosomepopulationofcasesinallrespectsthatmightaffecttheX1/Yrelationshipofinterest(i.e.unit
homogeneous).Itisatthispointthatitbecomespossibletosay,withinthecontextofacross‐casestatistical
model,whetheracaseliesnearto,orfarfrom,theregressionline.However,thissortofanalysismeansthatthe
researcherisnolongerpursuinganextreme‐casemethod.Theextreme‐casemethodispurelyexploratory—a
wayofprobingpossiblecausesofY,orpossibleeffectsofX,inanopen‐endedfashion.Iftheresearcherhassome
notionofwhatadditionalfactorsmightaffecttheoutcomeofinterest,orofwhatrelationshipthecausalfactorof
interestmighthavewithY,thensheoughttopursueoneoftheothermethodsexploredinthischapter.Thisalso
impliesthatanextreme‐casemethodmaytransformintoadifferentkindofapproachasastudyevolves;thatis,as
amorespecifichypothesiscomestolight.Usefulextremecasesattheoutsetofastudymayprovelessusefulata
laterstageofanalysis.
(p.655) 4DeviantCase
Thedeviant‐casemethodselectsthatcase(s)which,byreferencetosomegeneralunderstandingofatopic
(eitheraspecifictheoryorcommonsense),demonstratesasurprisingvalue.Itisthusthecontraryofthetypical
case.BarbaraGeddes(2003)notestheimportanceofdeviantcasesinmedicalscience,whereresearchersare
habituallyfocusedonthatwhichis“pathological”(accordingtostandardtheoryandpractice).TheNewEngland
JournalofMedicine,oneofthepremierjournalsofthefield,carriesaregularfeatureentitledCaseRecordsofthe
MassachusettsGeneralHospital.Thesearticlesbeartitleslikethefollowing:“An80‐Year‐OldWomanwithSudden
UnilateralBlindness”or“A76‐Year‐OldManwithFever,Dyspnea,PulmonaryInfiltrates,PleuralEffusions,and
Confusion.”9 Anotherinterestingexampledrawnfromthefieldofmedicineconcernstheextensivestudynow
devotedtoasmallnumberofpersonswhoseemresistanttotheAIDSvirus(BuchbinderandVittinghoff1999;
Haynes,Pantaleo,andFauci1996).Whyaretheyresistant?Whatisdifferentaboutthesepeople?Whatcanwe
learnaboutAIDSinotherpatientsbyobservingpeoplewhohavebuilt‐inresistancetothisdisease?
Likewise,inpsychologyandsociologycasestudiesmaybecomprisedofdeviant(inthesocialsense)personsor
groups.Ineconomics,casestudiesmayconsistofcountriesorbusinessesthatoverperform(e.g.Botswana;
Microsoft)orunderperform(e.g.Britainthroughmostofthetwentiethcentury;Searsinrecentdecades)relativeto
somesetofexpectations.Inpoliticalscience,casestudiesmayfocusoncountrieswherethewelfarestateismore
developed(e.g.Sweden)orlessdeveloped(e.g.theUnitedStates)thanonewouldexpect,givenasetofgeneral
expectationsaboutwelfarestatedevelopment.Thedeviantcaseiscloselylinkedtotheinvestigationoftheoretical
anomalies.Indeed,tosaydeviantistoimply“anomalous.”10
Notethatwhileextremecasesarejudgedrelativetothemeanofasingledistribution(thedistributionofvalues
alongasinglevariable),deviantcasesarejudgedrelativetosomegeneralmodelofcausalrelations.Thedeviant‐
casemethodselectscaseswhich,byreferencetosome(presumably)generalrelationship,demonstratea
surprisingvalue.Theyare“deviant”inthattheyarepoorlyexplainedbythemultivariatemodel.Theimportant
pointisthatdeviant‐nesscanonlybeassessedrelativetothegeneral(quantitativeorqualitative)model.This
meansthattherelativedeviant‐nessofacaseislikelytochangewheneverthegeneralmodelisaltered.For
example,theUnitedStatesisadeviantwelfarestatewhenthisoutcomeisgaugedrelativetosocietalwealth.Butit
islessdeviant—andperhapsnotdeviantatall—whencertainadditional(politicalandsocietal)factorsareincluded
inthemodel,asdiscussedin(p.656) theepilogue.Devianceismodeldependent.Thus,whendiscussingthe
conceptofthedeviantcaseitishelpfultoaskthefollowingquestion:Relativetowhatgeneralmodel(orsetof
backgroundfactors)isCaseAdeviant?
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Conceptually,wehavesaidthatthedeviantcaseisthelogicalcontraryofthetypicalcase.Thistranslatesintoa
directlycontrastingstatisticalmeasurement.Whilethetypicalcaseisonewithalowresidual(insomegeneral
modelofcausalrelations),adeviantcaseisonewithahighresidual.Thismeans,followingourprevious
discussion,thatthedeviantcaseislikelytobeanunrepresentativecase,andinthisrespectappearstoviolatethe
suppositionthatcase‐studysamplesshouldseektoreproducefeaturesofalargerpopulation.
However,itmustbeborneinmindthattheprimarypurposeofadeviant‐caseanalysisistoprobefornew—butas
yetunspecified—explanations.(IfthepurposeistodisproveanextanttheoryIshallrefertothestudyascrucial‐
case,asdiscussedbelow.)Theresearcherhopesthatcausalprocessesidentifiedwithinthedeviantcasewill
illustratesomecausalfactorthatisapplicabletoother(moreorlessdeviant)cases.Thismeansthatadeviant‐
casestudyusuallyculminatesinageneralproposition,onethatmaybeappliedtoothercasesinthepopulation.
Oncethisgeneralpropositionhasbeenintroducedintotheoverallmodel,theexpectationisthatthechosencase
willnolongerbeanoutlier.Indeed,thehopeisthatitwillnowbetypical,asjudgedbyitssmallresidualinthe
adjustedmodel.(Theexceptionwouldbeacircumstanceinwhichacase'soutcomeisdeemedtobe“accidental,”
andthereforeinexplicablebyanygeneralmodel.)
Thisfeatureofthedeviant‐casestudyshouldhelptoresolvequestionsaboutitsrepresentativeness.Evenifitis
notpossibletomeasurethenewcausalfactor(andthustointroduceitintoalarge‐Ncross‐casemodel),itmaystill
beplausibletoassert(basedongeneralknowledgeofthephenomenon)thatthechosencaseisrepresentativeof
abroaderpopulation.
5InfluentialCase
Sometimes,thechoiceofacaseismotivatedsolelybytheneedtoverifytheassumptionsbehindageneralmodel
ofcausalrelations.Here,theanalystattemptstoprovidearationalefordisregardingaproblematiccaseorasetof
problematiccases.Thatistosay,sheattemptstoshowwhyapparentdeviationsfromthenormarenotreally
deviant,ordonotchallengethecoreofthetheory,oncethecircumstancesofthespecialcaseorcasesarefully
understood.Across‐caseanalysismay,afterall,bemarredbyseveralclassesofproblemsincluding
measurementerror,specificationerror,errorsinestablishingproperboundariesfortheinference(thescopeofthe
argument),andstochasticerror(fluctuationsinthephenomenonunderstudythataretreatedasrandom,given
availabletheoreticalresources).Ifpoorlyfittingcases(p.657) canbeexplainedawaybyreferencetothese
kindsofproblems,thenthetheoryofinterestisthatmuchstronger.Thissortofdeviant‐caseanalysisanswersthe
question,“WhataboutCaseA(orcasesoftypeA)?Howdoesthat,seeminglydisconfirming,casefitthemodel?”
Becauseitsunderlyingpurposeisdifferentfromtheusualdeviant‐casestudy,Iofferanewtermforthismethod.
Theinfluentialcaseisacasethatcastsdoubtuponatheory,andforthatreasonwarrantscloseinspection.This
investigationmayreveal,afterall,thatthetheoryisvalidated—perhapsinsomeslightlyalteredform.Inthisguise,
theinfluentialcaseisthe“casethatprovestherule.”Inotherinstances,theinfluential‐caseanalysismay
contributetodisconfirming,orreconceptualizing,atheory.Thekeypointisthatthevalueofthecaseisjudged
relativetosomeextantcross‐casemodel.
Asimpleversionofinfluential‐caseanalysisinvolvestheconfirmationofakeycase'sscoreonsomecritical
dimension.Thisisessentiallyaquestionofmeasurement.Sometimescasesarepoorlyexplainedsimplybecause
theyarepoorlyunderstood.Acloseexaminationofaparticularcontextmayrevealthatanapparentlyfalsifying
casehasbeenmiscoded.Ifso,theinitialchallengepresentedbythatcasetosomegeneraltheoryhasbeen
obviated.
However,themoreusualemploymentoftheinfluential‐casemethodculminatesinasubstantivereinterpretationof
thecase—perhapsevenofthegeneralmodel.Itisnotjustaquestionofmeasurement.ConsiderThomasErtman's
(1997)studyofstatebuildinginWesternEurope,assummarizedbyGerardoMunck.Thisstudyargues
thattheinteractionofa)thetypeoflocalgovernmentduringthefirstperiodofstatebuilding,withb)the
timingofincreasesingeopoliticalcompetition,stronglyinfluencesthekindofregimeandstatethat
emerge.[Ertman]teststhishypothesisagainstthehistoricalexperienceofEuropeandfindsthatmost
countriesfithispredictions.Denmark,however,isamajorexception.InDenmark,sustainedgeopolitical
competitionbeganrelativelylateandlocalgovernmentatthebeginningofthestatebuildingperiodwas
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generallyparticipatory,whichshouldhaveledthecountrytodevelop“patrimonialconstitutionalism.”But
infact,itdeveloped“bureaucraticabsolutism.”Ertmancarefullyexplorestheprocessthroughwhich
DenmarkcametohaveabureaucraticabsolutiststateandfindsthatDenmarkhadtheearlymarksofa
patrimonialconstitutionaliststate.However,thecountrywaspushedoffthisdevelopmentalpathbythe
influenceofGermanknights,whoenteredDenmarkandbroughtwiththemGermaninstitutionsoflocal
government.Ertmanthentracesthecausalprocessthroughwhichtheseimportedinstitutionspushed
Denmarktodevelopbureaucraticabsolutism,concludingthatthisdevelopmentwascausedbyafactor
welloutsidehisexplanatoryframework.
(Munck2004,118)
Ertman'soverallframeworkisconfirmedinsofarashehasbeenabletoshow,byanin‐depthdiscussionof
Denmark,thatthecausalprocessesstipulatedbythegeneraltheoryholdeveninthisapparentlydisconfirming
case.Denmarkisstilldeviant,butitissobecauseof“contingenthistoricalcircumstances”thatareexogenousto
thetheory(Ertman1997,316).
Evidently,theinfluential‐caseanalysisissimilartothedeviant‐caseanalysis.Bothfocusonoutliers.However,as
weshallsee,theyfocusondifferentkindsofoutliers.(p.658) Moreover,theanimatinggoalsofthesetwo
researchdesignsarequitedifferent.Theinfluential‐casestudybeginswiththeaimofconfirmingageneralmodel,
whilethedeviant‐casestudyhastheaimofgeneratinganewhypothesisthatmodifiesanexistinggeneralmodel.
Theconfusionstemsfromthefactthatthesamecasestudymayfulfillbothobjectives—qualifyingageneralmodel
and,atthesametime,confirmingitscorehypothesis.
Thus,intheirstudyofRobertoMichels's“ironlawofoligarchy,”Lipset,Trow,andColeman(1956)choosetofocus
onanorganization—theInternationalTypographicalUnion—thatappearstoviolatethecentralpresupposition.The
ITU,asnotedbyoneoftheauthors,has“along‐termtwo‐partysystemwithfreeelectionsandfrequentturnoverin
office”andisthusanythingbutoligarchic(Lipset1959,70).Assuch,itcallsintoquestionMichels'sgrand
generalizationaboutorganizationalbehavior.Theauthorsexplainthiscuriousresultbytheextraordinarilyhigh
levelofeducationamongthemembersofthisunion.Michels'slawisshowntobetrueformostorganizations,but
notall.Itistrue,withqualifications.Notethattherespecificationoftheoriginalmodel(ineffect,Lipset,Trow,and
Colemanintroduceanewcontrolvariableorboundarycondition)involvestheexplorationofanewhypothesis.In
thisinstance,therefore,theuseofaninfluentialcasetoconfirmanexistingtheoryisquitesimilartotheuseofa
deviantcasetoexploreanewtheory.
Inaquantitativeidiom,influentialcasesarethosethat,ifcounterfactuallyassignedadifferentvalueonthe
dependentvariable,wouldmostsubstantiallychangetheresultingestimates.Theymayormaynotbeoutliers
(high‐residualcases).Twoquantitativemeasuresofinfluencearecommonlyappliedinregressiondiagnostics
(Belsey,Kuh,andWelsch2004).Thefirst,oftenreferredtoastheleverageofacase,derivesfromwhatiscalled
thehatmatrix.Basedsolelyoneachcase'sscoresontheindependentvariables,thehatmatrixtellsushowmuch
achangein(orameasurementerroron)thedependentvariableforthatcasewouldaffecttheoverallregression
line.ThesecondisCook'sdistance,ameasureoftheextenttowhichtheestimatesofalltheparameterswould
changeifagivencasewereomittedfromtheanalysis.CaseswithalargeleverageorCook'sdistancecontribute
quitealottotheinferencesdrawnfromacross‐caseanalysis.Inthissense,suchcasesarevitalformaintaining
analyticconclusions.Discoveringasignificantmeasurementerroronthedependentvariableoranimportant
omittedvariableforsuchacasemaydramaticallyreviseestimatesoftheoverallrelationships.Hence,itmaybe
quitesensibletoselectinfluentialcasesforin‐depthstudy.
Notethattheuseofaninfluential‐casestrategyofcaseselectionislimitedtoinstancesinwhicharesearcherhas
reasontobeconcernedthatherresultsarebeingdrivenbyoneorafewcases.Thisismostlikelytobetruein
smalltomoderate‐sizedsamples.WhereNisverylarge—greaterthan1,000,letussay—itisextremelyunlikely
thatasmallsetofcases(muchlessanindividualcase)willplayan“influential”role.Ofcourse,theremaybe
influentialsetsofcases,e.g.countrieswithinaparticularcontinentorculturalregion,orpersonsofIrishextraction.
Setsofinfluentialobservationsareoftenproblematicinatime‐seriescross‐sectiondata‐setwhereeach(p.659)
unit(e.g.country)containsmultipleobservations(throughtime),andhencemayhaveastronginfluenceon
aggregateresults.Still,thegeneralruleis:thelargerthesample,thelessimportantindividualcasesarelikelytobe
and,hence,thelesslikelyaresearcheristouseaninfluential‐caseapproachtocaseselection.
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6CrucialCase
Ofalltheextantmethodsofcaseselectionperhapsthemoststoried—andcertainlythemostcontroversial—isthe
crucial‐casemethod,introducedtothesocialscienceworldseveraldecadesagobyHarryEckstein.Inhisseminal
essay,Eckstein(1975,118)describesthecrucialcaseasone“thatmustcloselyfitatheoryifoneistohave
confidenceinthetheory'svalidity,or,conversely,mustnotfitequallywellanyrulecontrarytothatproposed.”A
caseiscrucialinasomewhatweaker—butmuchmorecommon—sensewhenitismost,orleast,likelytofulfilla
theoreticalprediction.A“most‐likely”caseisonethat,onalldimensionsexceptthedimensionoftheoretical
interest,ispredictedtoachieveacertainoutcome,andyetdoesnot.Itisthereforeusedtodisconfirmatheory.A
“least‐likely”caseisonethat,onalldimensionsexceptthedimensionoftheoreticalinterest,ispredictednotto
achieveacertainoutcome,andyetdoesso.Itisthereforeusedtoconfirmatheory.Inallformulations,thecrucial‐
caseoffersamost‐difficulttestforanargument,andhenceprovideswhatisperhapsthestrongestsortof
evidencepossibleinanonexperimental,single‐casesetting.
SincethepublicationofEckstein'sinfluentialessay,thecrucial‐caseapproachhasbeenclaimedinamultitudeof
studiesacrossseveralsocialsciencedisciplinesandhascometoberecognizedasastapleofthecase‐study
method.11Yettheideaofanysinglecaseplayingacrucial(or“critical”)roleisnotwidelyacceptedamongmost
methodologists(e.g.Sekhon2004).(Evenitsprogenitorseemstohavehaddoubts.)
Letusbeginwiththeconfirmatory(a.k.a.least‐likely)crucialcase.Theimplicitlogicofthisresearchdesignmaybe
summarizedasfollows.Givenasetoffacts,weareaskedtocontemplatetheprobabilitythatagiventheoryistrue.
Whilethefactsmatter,tobesure,theeffectivenessofthissortofresearchalsorestsupontheformalpropertiesof
thetheoryinquestion.Specifically,thedegreetowhichatheoryisamenabletoconfirmationiscontingentupon
howmanypredictionscanbederivedfromthetheoryandonhow“risky”eachindividualpredictionis.InPopper's
(1963,36)words,“Confirmationsshouldcountonlyiftheyaretheresultofriskypredictions;thatistosay,if,
unenlightenedbythetheoryinquestion,weshouldhaveexpectedan(p.660) eventwhichwasincompatible
withthetheory—andeventwhichwouldhaverefutedthetheory.Every‘good’scientifictheoryisaprohibition;it
forbidscertainthingstohappen.Themoreatheoryforbids,thebetteritis”(seealsoPopper1934/1968).Arisky
predictionisthereforeonethatishighlypreciseanddeterminate,andthereforeunlikelytobeachievedbythe
productofothercausalfactors(externaltothetheoryofinterest)orthroughstochasticprocesses.Atheory
producesmanysuchpredictionsifitisfullyelaborated,issuingpredictionsnotonlyonthecentraloutcomeof
interestbutalsoonspecificcausalmechanisms,andifitisbroadinpurview.(Thenotionofriskinessmayalsobe
conceptualizedwithinthePopperianlexiconasdegreesoffalsifiability.)
ThesepointscanalsobearticulatedinBayesianterms.ColinHowsonandPeterUrbachexplain:“Thedegreeto
whichh[ahypothesis]isconfirmedbye[asetofevidence]depends…ontheextenttowhichP(eČh)exceedsP
(e),thatis,onhowmuchmoreprobableeisrelativetothehypothesisandbackgroundassumptionsthanitis
relativejusttobackgroundassumptions.”Again,“confirmationiscorrelatedwithhowmuchmoreprobablethe
evidenceisifthehypothesisistruethanifitisfalse”(HowsonandUrlbach1989,86).Thus,thestrangerthe
predictionofferedbyatheory—relativetowhatwewouldnormallyexpect—thegreaterthedegreeofconfirmation
thatwillbeaffordedbytheevidence.Asanintuitiveexample,HowsonandUrbach(1989,86)offerthefollowing:
Ifasoothsayerpredictsthatyouwillmeetadarkstrangersometimeandyoudoinfact,yourfaithinhis
powersofprecognitionwouldnotbemuchenhanced:youwouldprobablycontinuetothinkhispredictions
werejusttheresultofguesswork.However,ifthepredictionalsogavethecorrectnumberofhairsonthe
headofthatstranger,yourpreviousscepticismwouldnodoubtbeseverelyshaken.
WhilethesePopperian/Bayesiannotions12 arerelevanttoallempiricalresearchdesigns,theyareespecially
relevanttocase‐studyresearchdesigns,forinthesesettingsasinglecase(or,atmost,asmallnumberofcases)
isrequiredtobearaheavyburdenofproof.Itshouldbenosurprise,therefore,thatPopper'sideaof“riskiness”
wastobeappropriatedbycase‐studyresearcherslikeHarryEcksteintovalidatetheenterpriseofsingle‐case
analysis.(AlthoughEcksteindoesnotcitePoppertheintellectuallineageisclear.)Riskiness,here,isanalogousto
whatisusuallyreferredtoasa“most‐difficult”researchdesign,whichinacase‐studyresearchdesignwouldbe
understoodasa“least‐likely”case.Notealsothatthedistinctionbetweena“must‐fit”caseandaleast‐likelycase
—that,intheevent,actuallydoesfitthetermsofatheory—isamatterofdegree.Casesaremoreorlesscrucialfor
confirmingtheories.Thepointisthat,insomecircumstances,apaucityofempiricalevidencemaybe
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compensatedbytheriskinessofthetheory.
Thecrucial‐caseresearchdesignis,perforce,ahighlydeductiveenterprise;muchdependsonthequalityofthe
theoryunderinvestigation.Itfollowsthatthetheoriesmostamenabletocrucial‐caseanalysisarethosewhichare
lawlikeintheirprecision,(p.661) degreeofelaboration,consistency,andscope.Themoreatheoryattainsthe
statusofacausallaw,theeasieritwillbetoconfirm,ortodisconfirm,withasinglecase.Indeed,riskypredictions
arecommoninnaturalsciencefieldssuchasphysics,whichinturnservedasthetemplateforthedeductive‐
nomological(“covering‐law”)modelofsciencethatinfluencedEcksteinandothersinthepostwardecades(e.g.
Hempel1942).
Afrequentlycitedexampleisthefirstimportantempiricaldemonstrationofthetheoryofrelativity,whichtookthe
formofasingle‐eventpredictionontheoccasionoftheMay29,1919,solareclipse(Eckstein1975;Popper1963).
StephenVanEvera(1997,66–7)describestheimpactofthispredictiononthevalidationofEinstein'stheory.
Einstein'stheorypredictedthatgravitywouldbendthepathoflighttowardagravitysourcebyaspecific
amount.Henceitpredictedthatduringasolareclipsestarsnearthesunwouldappeardisplaced—stars
actuallybehindthesunwouldappearnexttoit,andstarslyingnexttothesunwouldappearfartherfromit
—anditpredictedtheamountofapparentdisplacement.Noothertheorymadethesepredictions.The
passageofthisonesingle‐case‐studytestbroughtthetheorywideacceptancebecausethetested
predictionswereunique—therewasnoplausiblecompetingexplanationforthepredictedresult—hence
thepassedtestwasverystrong.
Thestrengthofthistestistheextraordinaryfitbetweenthetheoryandasetoffactsfoundinasinglecase,and
thecorrespondinglackoffitbetweenallothertheoriesandthissetoffacts.Einsteinofferedanexplanationofa
particularsetofanomalousfindingsthatnootherexistingtheorycouldmakesenseof.Ofcourse,onemust
assumethattherewasno—orlimited—measurementerror.Andonemustassumethatthephenomenonofinterest
islargelyinvariant;lightdoesnotbenddifferentlyatdifferenttimesandplaces(exceptinwaysthatcanbe
understoodthroughthetheoryofrelativity).Andonemustassume,finally,thatthetheoryitselfmakessenseon
othergrounds(otherthanthecaseofspecialinterest);itisaplausiblegeneraltheory.Ifoneiswillingtoaccept
theseaprioriassumptions,thenthe1919“casestudy”providesaverystrongconfirmationofthetheory.Itis
difficulttoimagineastrongerproofofthetheoryfromwithinanobservational(nonexperimental)setting.
Insocialsciencesettings,bycontrast,onedoesnotcommonlyfindsingle‐casestudiesofferingknockoutevidence
foratheory.Thisis,inmyview,largelyaproductofthelooseness(theunderspecification)ofmostsocialscience
theories.GeorgeandBennettpointoutthatwhilethethesisofthedemocraticpeaceisasclosetoa“law”as
socialsciencehasyetseen,itcannotbeconfirmed(orrefuted)bylookingatspecificcausalmechanismsbecause
thecausalpathwaysmandatedbythetheoryaremultipleanddiverse.Underthecircumstances,nosingle‐case
testcanofferstrongconfirmationofthetheory(GeorgeandBennett2005,209).
However,ifoneadoptsasofterversionofthecrucial‐casemethod—theleast‐likely(mostdifficult)case—then
possibilitiesabound.Indeed,Isuspectthat,implicitly,mostcase‐studyworkthatmakesapositiveargument
focusingonasinglecase(withoutacorrespondingcross‐caseanalysis)relieslargelyonthelogicoftheleast‐
likelycase.Rarelyisthislogicmadeexplicit,exceptperhapsinapassingphraseortwo.Yetthedeductivelogicof
the“risky”predictioniscentraltothecase‐studyenterprise.(p.662) Whetheracasestudyisconvincingornot
oftenrestsonthereader'sevaluationofhowstrongtheevidenceforanargumentmightbe,andthisinturn—
wherevercross‐caseevidenceislimitedandnomanipulatedtreatmentcanbedevised—restsuponanestimation
ofthedegreeof“fit”betweenatheoryandtheevidenceathand,asdiscussed.
LilyTsai's(2007)investigationofgovernanceatthevillagelevelinChinaemploysseveralin‐depthcasestudiesof
villageswhicharechosen(inpart)becauseoftheirleast‐likelystatusrelativetothetheoryofinterest.Tsai's
hypothesisisthatvillageswithgreatersocialsolidarity(basedonpreexistingreligiousorfamilialnetworks)will
developahigherlevelofsocialtrustandmutualobligationand,asaresult,willexperiencebettergovernance.
Crucialcases,therefore,arevillagesthatevidenceahighlevelofsocialsolidaritybutwhich,alongother
dimensions,wouldbejudgedleastlikelytodevelopgoodgovernance,e.g.theyarepoor,isolated,andlack
democraticinstitutionsoraccountabilitymechanismsfromabove.“LiSettlement,”inFujianprovince,issucha
case.Thefactthatthisimpoverishedvillagenonethelessboastsanimpressivesetofinfrastructural
accomplishmentssuchaspavedroadswithdrainageditches(ararityinruralChina)suggeststhatsomething
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ratherunusualisgoingonhere.Becausehercaseiscarefullychosentoeliminaterivalexplanations,Tsai's
conclusionsaboutthespecialroleofsocialsolidarityaredifficulttogainsay.Howelseisonetoexplainthis
otherwiseanomalousresult?Thisisthestrengthoftheleast‐likelycase,whereallotherplausiblecausalfactorsfor
anoutcomehavebeenminimized.13
JackLevy(2002,144)referstothis,evocatively,asa“Sinatrainference:”ifitcanmakeithere,itcanmakeit
anywhere(seealsoKhong1992,49;Sagan1995,49;Shafer1988,14–6).Thus,ifsocialsolidarityhasthe
hypothesizedeffectinLiSettlementitshouldhavethesameeffectinmorepropitioussettings(e.g.wherethereis
greatereconomicsurplus).Thesameimplicitlogicinformsmanycase‐studyanalyseswheretheintentofthestudy
istoconfirmahypothesisonthebasisofasinglecase.
Anothersortofcrucialcaseisemployedforthepurposeofdisconfirmingacausalhypothesis.AcentralPopperian
insightisthatitiseasiertodisconfirmaninferencethantoconfirmthatsameinference.(Indeed,Popperdoubted
thatanyinferencecouldbefullyconfirmed,andforthisreasonpreferredtheterm“corroborate.”)Thisis
particularlytrueofcase‐studyresearchdesigns,whereevidenceislimitedtooneorseveralcases.Thekey
provisoisthatthetheoryunderinvestigationmusttakeaconsistent(a.k.a.invariant,deterministic)form,evenifits
predictionsarenotterrificallyprecise,wellelaborated,orbroad.
Asithappens,thereareafairnumberofinvariantpropositionsfloatingaroundthesocialsciencedisciplines
(GoertzandLevyforthcoming;GoertzandStarr2003).Itusedtobeargued,forexample,thatpoliticalstability
wouldoccuronlyincountriesthatarerelativelyhomogeneous,orwhereexistingheterogeneitiesaremitigatedby
(p.663) cross‐cuttingcleavages(Almond1956;Bentley1908/1967;Lipset1960/1963;Truman1951).Arend
Lijphart's(1968)studyoftheNetherlands,apeacefulcountrywithreinforcingsocialcleavages,iscommonly
viewedasrefutingthistheoryonthebasisofasinglein‐depthcaseanalysis.14
Granted,itmaybequestionedwhetherpresumedinvarianttheoriesarereallyinvariant;perhapstheyarebetter
understoodasprobabilistic.Perhaps,thatis,thetheoryofcross‐cuttingcleavagesisstilltrue,probabilistically,
despitetheapparentDutchexception.Orperhapsthetheoryisstilltrue,deterministically,withinasubsetofcases
thatdoesnotincludetheNetherlands.(Thissortofclaimseemsunlikelyinthisparticularinstance,butitisquite
plausibleinmanyothers.)Orperhapsthetheoryisinneedofreframing;itistrue,deterministically,butappliesonly
tocross‐cuttingethnic/racialcleavages,nottocleavagesthatareprimarilyreligious.Onecanquibbleoverwhatit
meansto“disconfirm”atheory.Thepointisthatthecrucialcasehas,inallthesecircumstances,provided
importantupdatingofatheoreticalprior.
Heretofore,Ihavetreatedcausalfactorsasdichotomous.Countrieshaveeitherreinforcingorcross‐cutting
cleavagesandtheyhaveregimesthatareeitherpeacefulorconflictual.Evidently,thesesortsofparametersare
oftenmattersofdegree.Inthisreadingofthetheory,casesaremoreorlesscrucial.Accordingly,themostuseful
—i.e.mostcrucial—caseforLijphart'spurposeisonethathasthemostsegregatedsocialgroupsandthemost
peacefulanddemocratictrackrecord.Intheserespects,theNetherlandswasaverygoodchoice.Indeed,the
degreeofdisconfirmationofferedbythiscasestudyisprobablygreaterthanthedegreeofdisconfirmationthat
mighthavebeenprovidedbyothercasessuchasIndiaorPapuaNewGuinea—countrieswheresocialpeacehas
notalwaysbeensecure.Thepointisthatwherevariablesarecontinuousratherthandichotomousitispossibleto
evaluatepotentialcasesintermsoftheirdegreeofcrucialness.
Notethatthecrucial‐casemethodofcase‐selection,whetheremployedinaconfirmatoryordisconfirmatorymode,
cannotbeemployedinalarge‐Ncontext.Thisisbecauseanexplicitcross‐casemodelwouldrenderthecrucial‐
casestudyredundant.Onceoneidentifiestherelevantparametersandthescoresofallcasesonthose
parameters,onehasineffectconstructedacross‐casemodelthatconfirmsordisconfirmsthetheoryinquestion.
Thecasestudyisthenceforthirrelevant,atleastasameansofdecisiveconfirmationordisconfirmation.15It
remainshighlyrelevantasameansofexploringcausalmechanisms,ofcourse.Yet,becausethisobjectiveisquite
differentfromthatwhichisusuallyassociatedwiththeterm,Ienlistanewtermforthistechnique.
(p.664) 7PathwayCase
Oneofthemostimportantfunctionsofcase‐studyresearchistheelucidationofcausalmechanisms.Butwhichsort
ofcaseismostusefulforthispurpose?Althoughallcasestudiespresumablyshedlightoncausalmechanisms,not
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allcasesareequallytransparent.Insituationswhereacausalhypothesisisclearandhasalreadybeenconfirmed
bycross‐caseanalysis,researchersarewelladvisedtofocusonacasewherethecausaleffectofX1onYcan
beisolatedfromotherpotentiallyconfoundingfactors(X2 ).Ishallcallthisapathwaycasetoindicateitsuniquely
penetratinginsightintocausalmechanisms.Incontrasttothecrucialcase,thissortofmethodispracticableonlyin
circumstanceswherecross‐casecovariationalpatternsarewellstudiedandwherethemechanismlinkingX1and
Yremainsdim.Becausethepathwaycasebuildsonpriorcross‐caseanalysis,theproblemofcaseselectionmust
besituatedwithinthatsample.Thereisnostandalonepathwaycase.
Thelogicofthepathwaycaseisclearestinsituationsofcausalsufficiency—whereacausalfactorofinterest,X1,
issufficientbyitself(thoughperhapsnotnecessary)toaccountforY'svalue(0or1).TheothercausesofY,about
whichweneedmakenoassumptions,aredesignatedasavector,X2 .
Notethatwherevervariouscausalfactorsaresubstitutableforoneanother,eachfactorisconceptualized
(individually)assufficient(Braumoeller2003).Thus,situationsofcausalequifinalitypresumecausalsufficiencyon
thepartofeachfactororsetofconjointfactors.Anexampleisprovidedbytheliteratureondemocratization,
whichstipulatesthreemainavenuesofregimechange:leadership‐initiatedreform,acontrolledopeningto
opposition,orthecollapseofanauthoritarianregime(Colomer1991).Thecase‐studyformatconstrainsusto
analyzeoneatatime,soletuslimitourscopetothefirstone—leadership‐initiatedreform.Soconsidered,a
causal‐pathwaycasewouldbeonewiththefollowingfeatures:(a)democratization,(b)leadership‐initiatedreform,
(c)nocontrolledopeningtotheopposition,(d)nocollapseofthepreviousauthoritarianregime,and(e)noother
extraneousfactorsthatmightaffecttheprocessofdemocratization.Inacaseofthistype,thecausalmechanisms
bywhichleadership‐initiatedreformmayleadtodemocratizationwillbeeasiesttostudy.Notethatitisnot
necessarytoassumethatleadership‐initiatedreformalwaysleadstodemocratization;itmayormaynotbea
deterministiccause.Butitisnecessarytoassumethatleadership‐initiatedreformcansometimesleadto
democratizationonitsown(givencertainbackgroundfeatures).
Nowletusmovefromtheseexamplestoageneral‐purposemodel.Forheuristicpurposes,letuspresumethatall
variablesinthatmodelaredichotomous(codedas0or1)andthatthemodeliscomplete(allcausesofYare
included).Allcausalrelationshipswillbecodedsoastobepositive:X1andYcovaryasdoX2 andY.Thisallows
ustovisualizearangeofpossiblecombinationsataglance.
Recallthatthepathwaycaseisalwaysfocused,bydefinition,onasinglecausalfactor,denotedX1.(The
researcher'sfocusmayshifttoothercausalfactors,butmayonlyfocusononecausalfactoratatime.)Inthis
scenario,andregardlessofhow(p.665) manyadditionalcausesofYtheremightbe(denotedX2 ,avectorof
controls),thereareonlyeightrelevantcasetypes,asillustratedinTable28.2.Identifyingthesecasetypesisa
relativelysimplematter,andcanbeaccomplishedinasmall‐Nsamplebytheconstructionofatruth‐table
(modeledafterTable28.2)orinalarge‐Nsamplebytheuseofcross‐tabs.
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Table28.2.Pathwaycasewithdichotomouscausalfactors
Casetypes
X1
X2
Y
A
1
1
1
B
0
0
0
C
0
1
1
D
0
0
1
E
1
0
0
F
1
1
0
G
1
0
1
H
0
1
0
Notes:X1=thevariableoftheoreticalinterest.X2 =avectorofcontrols(ascoreof0indicatesthatallcontrol
variableshaveascoreof0,whileascoreof1indicatesthatallcontrolvariableshaveascoreof1).Y=the
outcomeofinterest.A–H=casetypes(theNforeachcasetypeisindeterminate).G,H=possiblepathway
cases.Samplesize=indeterminate.
Assumptions:(a)allvariablescanbecodeddichotomously(abinarycodingoftheconceptisvalid);(b)all
independentvariablesarepositivelycorrelatedwithYinthegeneralcase;(c)X1is(atleastsometimes)a
sufficientcauseofY.
Notethatthetotalnumberofcombinationsofvaluesdependsonthenumberofcontrolvariables,whichwehave
representedwithasinglevector,X2 .Ifthisvectorconsistsofasinglevariablethenthereareonlyeightcase
types.Ifthisvectorconsistsoftwovariables(X2a ,X2b )thenthetotalnumberofpossiblecombinationsincreases
fromeight(23 )tosixteen(24 ).Andsoforth.However,noneofthesecombinationsisrelevantforpresentpurposes
exceptthosewhereX2a andX2b havethesamevalue(0or1).“Mixed”casesarenotcausalpathwaycases,for
reasonsthatshouldbecomeclear.
Thepathwaycase,followingthelogicofthecrucialcase,isonewherethecausalfactorofinterest,X1,correctly
predictsYwhileallotherpossiblecausesofY(representedbythevector,X2 )make“wrong”predictions.IfX1is—
atleastinsomecircumstances—asufficientcauseofY,thenitisthesesortsofcasesthatshouldbemostuseful
fortracingcausalmechanisms.ThereareonlytwosuchcasesinTable28.2—GandH.Inallothercases,the
mechanismrunningfromX1toYwouldbedifficulttodiscerneitherbecauseX1andYarenotcorrelatedinthe
usualway(constitutinganunusualcase,inthetermsofourhypothesis)orbecauseotherconfoundingfactors(X
2 )intrude.IncaseA,forexample,thepositivevalueonY(p.666) couldbeaproductofX1orX2 .Anin‐depth
examinationofthiscaseisnotlikelytobeveryrevealing.
Keepinmindthatbecausetheresearcheralreadyknowsfromhercross‐caseexaminationwhatthegeneral
causalrelationshipsare,sheknows(priortothecase‐studyinvestigation)whatconstitutesacorrectorincorrect
prediction.Inthecrucial‐casemethod,bycontrast,theseexpectationsaredeductiveratherthanempirical.Thisis
whatdifferentiatesthetwomethods.Andthisiswhythecausalpathwaycaseisusefulprincipallyforelucidating
causalmechanismsratherthanverifyingorfalsifyinggeneralpropositions(whicharealreadymoreorless
apparentfromthecross‐caseevidence).Ofcourse,wemustleaveopenthepossibilitythattheinvestigationof
causalmechanismswouldinvalidateageneralclaim,ifthatclaimisutterlycontingentuponaspecificsetofcausal
mechanismsandthecasestudyshowsthatnosuchmechanismsarepresent.However,thisisratherunlikelyin
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mostsocialsciencesettings.Usually,theresultofsuchafindingwillbeareformulationofthecausalprocessesby
whichX1causesY—or,alternatively,arealizationthatthecaseunderinvestigationisaberrant(atypicalofthe
generalpopulationofcases).
Sometimes,theresearchquestionisframedasaunidirectionalcause:oneisinterestedinwhy0becomes1(or
viceversa)butnotinwhy1becomes0.Inourpreviousexample,weaskedwhydemocraciesfail,notwhy
countriesbecomedemocraticorauthoritarian.Soframed,therecanbeonlyonetypeofcausal‐pathwaycase.
(Whetherregimefailureiscodedas0or1isamatteroftaste.)Whereresearchersareinterestedinbidirectional
causality—amovementfrom0to1aswellasfrom1to0—therearetwopossiblecausal‐pathwaycases,GandH.
Inpractice,however,oneofthesecasetypesisalmostalwaysmoreusefulthantheother.Thus,itseems
reasonabletoemploytheterm“pathwaycase”inthesingular.Inordertodeterminewhichofthesetwocasetypes
willbemoreusefulforintensiveanalysistheresearchershouldlooktoseewhethereachcasetypeexhibits
desirablefeaturessuchas:(a)arare(unusual)valueonX1orY(designated“extreme”inourprevious
discussion),(b)observabletemporalvariationinX1,(c)anX1/Yrelationshipthatiseasiertostudy(ithasmore
visiblefeatures;itismoretransparent),or(d)alowerresidual(thusindicatingamoretypicalcase,withintheterms
ofthegeneralmodel).Usually,thechoicebetweenGandHisintuitivelyobvious.
Now,letusconsiderascenarioinwhichall(ormost)variablesofconcerntothemodelarecontinuous,ratherthan
dichotomous.Here,thejobofcaseselectionisconsiderablymorecomplex,forcausal“sufficiency”(intheusual
sense)cannotbeinvoked.Itisnolongerplausibletoassumethatagivencausecanbeentirelypartitioned,i.e.
rivalfactorseliminated.However,thesearchforapathwaycasemaystillbeviable.Whatwearelookingforinthis
scenarioisacasethatsatisfiestwocriteria:(1)itisnotanoutlier(oratleastnotanextremeoutlier)inthegeneral
modeland(2)itsscoreontheoutcome(Y)isstronglyinfluencedbythetheoreticalvariableofinterest(X1),taking
allotherfactorsintoaccount(X2 ).Inthissortofcaseitshouldbeeasiestto“see”thecausalmechanismsthatlie
betweenX1andY.
Achievingtheseconddesideratarequiresabitofmanipulation.Inordertodeterminewhich(nonoutlier)casesare
moststronglyaffectedbyX1,givenalltheother(p.667) parametersinthemodel,onemustcomparethesizeof
theresidualsforeachcaseinareducedformmodel,Y=Constant+X2 +Resreduced ,withthesizeofthe
residualsforeachcaseinafullmodel,Y=Constant+X2 +X1+Resfull.Thepathwaycaseisthatcase,orsetof
cases,whichshowsthegreatestdifferencebetweentheresidualforthereduced‐formmodelandthefullmodel
(ΔResidual).Thus,
Notethattheresidualforacasemustbesmallerinthefullmodelthaninthereduced‐formmodel;otherwise,the
additionofthevariableofinterest(X1)pullsthecaseawayfromtheregressionline.Wewanttofindacasewhere
theadditionofX1pushesthecasetowardstheregressionline,i.e.ithelpsto“explain”thatcase.
Asanexample,letussupposethatweareinterestedinexploringtheeffectofmineralwealthontheprospectsfor
democracyinasociety.Accordingtoagooddealofworkonthissubject,countrieswithabountyofnatural
resources—particularlyoil—arelesslikelytodemocratize(oroncehavingundergoneademocratictransition,are
morelikelytoreverttoauthoritarianrule)(Barro1999;Humphreys2005;Ross2001).Thecross‐countryevidence
isrobust.Yetasisoftenthecase,thecausalmechanismsremainratherobscure.Inordertobetterunderstandthis
phenomenonitmaybeworthwhiletoexploitthefindingsofcross‐countryregressionmodelsinordertoidentifya
countrywhoseregimetype(i.e.itsdemocracy“score”onsomegeneralindex)isstronglyaffectedbyitsnatural‐
researchwealth,allotherthingsheldconstant.Ananalysisofthissortidentifiestwocountries—theUnitedArab
EmiratesandKuwait—withhighΔResidualvaluesandmodestresidualsinthefullmodel(signifyingthatthese
casesarenotoutliers).Researchersseekingtoexploretheeffectofoilwealthonregimetypemightdowellto
focusonthesetwocasessincetheirpatternsofdemocracycannotbewellexplainedbyotherfactors—e.g.
economicdevelopment,religion,Europeaninfluence,orethnicfractionalization.Thepresenceofoilwealthin
thesecountrieswouldappeartohaveastrongindependenteffectontheprospectsfordemocratizationinthese
cases,aneffectthatiswellmodeledbygeneraltheoryandbytheavailablecross‐caseevidence.
Toreiterate,thelogicofcausal“elimination”ismuchmorecompellingwherevariablesaredichotomousandwhere
causalsufficiencycanbeassumed(X1issufficientbyitself,atleastinsomecircumstances,tocauseY).Where
variablesarecontinuous,thestrategyofthepathwaycaseismoredubious,forpotentiallyconfoundingcausal
factors(X2 )cannotbeneatlypartitioned.Evenso,wehaveindicatedwhytheselectionofapathwaycasemaybe
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alogicalapproachtocase‐studyanalysisinmanycircumstances.
Theexceptionsmaybebrieflynoted.Sometimes,whereallvariablesinamodelaredichotomous,thereareno
pathwaycases,i.e.nocasesoftypeGorH(inTable28.2).Thisisknownasthe“emptycell”problem,ora
problemofseverecausalmulticollinearity.Theuniverseofobservationaldatadoesnotalwaysobligeuswith
casesthatallowustoindependentlytestagivenhypothesis.Wherevariablesarecontinuous,theanalogous
problemisthatofacausalvariableofinterest(X1)that(p.668) hasonlyminimaleffectsontheoutcomeof
interest.Thatis,itsroleinthegeneralmodelisquiteminor.Inthesesituations,theonlycasesthatarestrongly
affectedbyX1—ifthereareanyatall—maybeextremeoutliers,andthesesortsofcasesarenotproperly
regardedasprovidingconfirmatoryevidenceforaproposition,forreasonsthatareabundantlyclearbynow.
Finally,itshouldbeclarifiedthattheidentificationofacausalpathwaycasedoesnotobviatetheutilityofexploring
othercases.Onemight,forexample,wanttocomparebothsortsofpotentialpathwaycases—GandH—witheach
other.Manyothercombinationssuggestthemselves.However,thissortofmulti‐caseinvestigationmovesbeyond
thelogicofthecausal‐pathwaycase.
8Most‐similarCases
Themost‐similarmethodemploysaminimumoftwocases.16 Initspurestform,thechosenpairofcasesissimilarin
allrespectsexceptthevariable(s)ofinterest.Ifthestudyisexploratory(i.e.hypothesisgenerating),the
researcherlooksforcasesthatdifferontheoutcomeoftheoreticalinterestbutaresimilaronvariousfactorsthat
mighthavecontributedtothatoutcome,asillustratedinTable28.3(A).Thisisacommonformofcaseselectionat
theinitialstageofresearch.Often,fruitfulanalysisbeginswithanapparentanomaly:twocasesareapparently
quitesimilar,andyetdemonstratesurprisinglydifferentoutcomes.Thehopeisthatintensivestudyofthesecases
willrevealone—oratmostseveral—factorsthatdifferacrossthesecases.Thesedifferingfactors(X1)arelooked
uponasputativecauses.Atthisstage,theresearchmaybedescribedbytheseconddiagraminTable28.3(B).
Sometimes,aresearcherbeginswithastronghypothesis,inwhichcaseherresearchdesignisconfirmatory
(hypothesistesting)fromtheget‐go.Thatis,shestrivestoidentifycasesthatexhibitdifferentoutcomes,different
scoresonthefactorofinterest,andsimilarscoresonallotherpossiblecausalfactors,asillustratedinthesecond
(hypothesis‐testing)diagraminTable28.3(B).
Thepointisthatthepurposeofamost‐similarresearchdesign,andhenceitsbasicsetup,oftenchangesasa
researchermovesfromanexploratorytoaconfirmatorymodeofanalysis.However,regardlessofwhereone
begins,theresults,whenpublished,looklikeahypothesis‐testingresearchdesign.Questionmarkshavebeen
removed:(A)becomes(B)inTable28.3.
Asanexample,letusconsiderLeonEpstein'sclassicstudyofpartycohesion,whichfocusesontwo“most‐similar”
countries,theUnitedStatesandCanada.Canadahashighlydisciplinedpartieswhosemembersvotetogetheron
theflooroftheHouseof(p.669) CommonswhiletheUnitedStateshasweak,undisciplinedparties,whose
membersoftendefectonfloorvotesinCongress.Inexplainingthesedivergentoutcomes,persistentovermany
years,Epsteinfirstdiscussespossiblecausalfactorsthatareheldmoreorlessconstantacrossthetwocases.
BoththeUnitedStatesandCanadainheritedEnglishpoliticalcultures,bothhavelargeterritoriesand
heterogeneouspopulations,botharefederal,andbothhavefairlyloosepartystructureswithstrongregionalbases
andaweakcenter.Thesearethe“control”variables.Wheretheydifferisinoneconstitutionalfeature:Canadais
parliamentarywhiletheUnitedStatesispresidential.AnditisthisinstitutionaldifferencethatEpsteinidentifiesas
thecrucial(differentiating)cause.(Forfurtherexamplesofthemost‐similarmethodseeBrenner1976;Hamilton
1977;Lipset1968;Miguel2004;Moulder1977;Posner2004.)
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Table28.3.Most‐similaranalysiswithtwocasetypes
Casetypes
X1
X2
Y
(A)Hypothesis‐generating(Y‐centered):
A
?
0
1
B
?
0
0
A
1
0
1
B
0
0
0
(B)Hypothesis‐testing(X1/Y‐centered):
X1=thevariableoftheoreticalinterest.X2 =avectorofcontrols.Y=theoutcomeofinterest.
Severalcaveatsapplytoanymost‐similaranalysis(inadditiontotheusualsetofassumptionsapplyingtoallcase‐
studyanalysis).First,eachcausalfactorisunderstoodashavinganindependentandadditiveeffectonthe
outcome;thereareno“interaction”effects.Second,onemustcodecasesdichotomously(high/low,
present/absent).Thisisstraightforwardiftheunderlyingvariablesarealsodichotomous(e.g.federal/unitary).
However,itisoftenthecasethatvariablesofconcerninthemodelarecontinuous(e.g.partycohesion).Inthis
setting,theresearchermust“dichotomize”thescoringofcasessoastosimplifythetwo‐caseanalysis.(Some
flexibilityisadmissibleonthevectorofcontrols(X2 )thatare“heldconstant”acrossthecases.Nonidentityis
tolerableifthedeviationrunscountertothepredictedhypothesis.Forexample,EpsteindescribesboththeUnited
StatesandCanadaashavingstrongregionalbasesofpower,afactorthatisprobablymoresignificantinrecent
CanadianhistorythaninrecentAmericanhistory.However,becauseregionalbasesofpowershouldleadto
weakerparties,ratherthanstrongerparties,thiselementofnonidentitydoesnotchallengeEpstein'sconclusions.
Indeed,itsetsupamost‐difficultresearchscenario,asdiscussedabove.)
Inonerespecttherequirementsforcasecontrolarenotsostringent.Specifically,itisnotusuallynecessaryto
measurecontrolvariables(atleastnotwithahighdegreeofprecision)inordertocontrolforthem.Iftwocountries
canbeassumed(p.670) tohavesimilarculturalheritagesoneneedn'tworryaboutconstructingvariablesto
measurethatheritage.Onecansimplyassertthat,whatevertheyare,theyaremoreorlessconstantacrossthe
twocases.Thisissimilartothetechniqueemployedinarandomizedexperiment,wheretheresearchertypically
doesnotattempttomeasureallthefactorsthatmightaffectthecausalrelationshipofinterest.Sheassumes,
rather,thattheseunknownfactorshavebeenneutralizedacrossthetreatmentandcontrolgroupsby
randomizationorbythechoiceofasamplethatisinternallyhomogeneous.
Themostusefulstatisticaltoolforidentifyingcasesforin‐depthanalysisinamost‐similarsettingisprobablysome
varietyofmatchingstrategy—e.g.exactmatching,approximatematching,orpropensity‐scorematching.17 The
productofthisprocedureisasetofmatchedcasesthatcanbecomparedinwhateverwaytheresearcherdeems
appropriate.Thesearethe“most‐similar”cases.RosenbaumandSilber(2001,223)summarize:
Unlikemodel‐basedadjustments,where[individuals]vanishandarereplacedbythecoefficientsofa
model,inmatching,ostensiblycomparablepatternsarecompareddirectly,onebyone.Modernmatching
methodsinvolvestatisticalmodelingandcombinatorialalgorithms,buttheendresultisacollectionofpairs
orsetsofpeoplewholookcomparable,atleastonaverage.Inmatching,peopleretaintheirintegrityas
people,sotheycanbeexaminedandtheirstoriescanbetoldindividually.
Matching,concludetheauthors,“facilitates,ratherthaninhibits,thickdescription”(RosenbaumandSilber2001,
223).
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Inprinciple,thesamematchingtechniquesthathavebeenusedsuccessfullyinobservationalstudiesofmedical
treatmentsmightalsobeadaptedtothestudyofnationstates,politicalparties,cities,orindeedanytraditional
pairedcasesinthesocialsciences.Indeed,thecurrentpopularityofmatchingamongstatisticians—relative,that
is,togarden‐varietyregressionmodels—restsuponwhatqualitativeresearcherswouldrecognizeasa“case‐
based”approachtocausalanalysis.IfRosenbaumandSilberarecorrect,itmaybeperfectlyreasonableto
appropriatethislarge‐Nmethodofanalysisforcase‐studypurposes.
Aswithothermethodsofcaseselection,themost‐similarmethodispronetoproblemsofnonrepresentativeness.If
employedinaqualitativefashion(withoutasystematiccross‐caseselectionstrategy),potentialbiasesinthe
chosencasemustbeaddressedinaspeculativeway.Iftheresearcheremploysamatchingtechniqueofcase
selectionwithinalarge‐Nsample,theproblemofpotentialbiascanbeaddressedbyassuringthechoiceofcases
thatarenotextremeoutliers,asjudgedbytheirresidualsinthefullmodel.Most‐similarcasesshouldalsobe
“typical”cases,thoughsomescopefordeviancearoundtheregressionlinemaybeacceptableforpurposesof
findingagoodfitamongcases.(p.671)
Table28.4.Most‐differentanalysiswithtwocases
Casetypes
X1
X2a
X2b
X2c
X2d
Y
A
1
1
0
1
0
1
B
1
0
1
0
1
1
X1=thevariableoftheoreticalinterest.X2a–d =avectorofcontrols.Y=theoutcomeofinterest.
9Most‐differentCases
Afinalcase‐selectionmethodisthereverseimageofthepreviousmethod.Here,variationonindependent
variablesisprized,whilevariationontheoutcomeiseschewed.Ratherthanlookingforcasesthataremost‐
similar,onelooksforcasesthataremost‐different.Specifically,theresearchertriestoidentifycaseswherejust
oneindependentvariable(X1),aswellasthedependentvariable(Y),covary,whileallotherplausiblefactors(X
18
2a–d )showdifferentvalues.
Thesimplestformofthistwo‐casecomparisonisillustratedinTable28.4.CasesAandBaredeemed“most
different,”thoughtheyaresimilarintwoessentialrespects—thecausalvariableofinterestandtheoutcome.
Asanexample,IfollowMarcHoward's(2003)recentwork,whichexplorestheenduringimpactofCommunismon
civilsociety.19 Cross‐nationalsurveysshowastrongcorrelationbetweenformerCommunistregimesandlow
socialcapital,controllingforavarietyofpossibleconfounders.Itisastrongresult.Howardwonderswhythis
relationshipissostrongandwhyitpersists,andperhapsevenstrengthens,incountriesthatarenolongersocialist
orauthoritarian.Inordertoanswerthisquestion,hefocusesontwomost‐differentcases,RussiaandEast
Germany.Thesetwocountrieswerequitedifferent—inallwaysotherthantheirCommunistexperience—priorto
theSovietera,duringtheSovietera(sinceEastGermanyreceivedsubstantialsubsidiesfromWestGermany),and
inthepost‐Sovietera,asEastGermanywasabsorbedintoWestGermany.Yet,theybothscorenearthebottomof
variouscross‐nationalindicesintendedtomeasuretheprevalenceofcivicengagementinthecurrentera.Thus,
Howard's(2003,6–9)caseselectionproceduremeetstherequirementsofthemost‐differentresearchdesign:
Varianceisfoundonall(ormost)dimensions(p.672) asidefromthekeyfactorofinterest(Communism)andthe
outcome(civicengagement).
Whatleverageisbroughttotheanalysisfromthisapproach?Howard'scasestudiescombineevidencedrawnfrom
masssurveysandfromin‐depthinterviewsofsmall,stratifiedsamplesofRussiansandEastGermans.(Thisisa
goodillustration,incidentally,ofhowquantitativeandqualitativeevidencecanbefruitfullycombinedinthe
intensivestudyofseveralcases.)Theproductofthisanalysisistheidentificationofthreecausalpathwaysthat,
Howard(2003,122)claims,helptoexplainthelaggardstatusofcivilsocietyinpost‐Communistpolities:“the
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mistrustofcommunistorganizations,thepersistenceoffriendshipnetworks,andthedisappointmentwithpost‐
communism.”Simplyput,Howard(2003,145)concludes,“agreatnumberofcitizensinRussiaandEastern
Germanyfeelastrongandlingeringsenseofdistrustofanykindofpublicorganization,ageneralsatisfactionwith
theirownpersonalnetworks(accompaniedbyasenseofdeterioratingrelationswithinsocietyoverall),and
disappointmentinthedevelopmentsofpost‐communism.”
Thestrengthofthismost‐differentcaseanalysisisthattheresultsobtainedinEastGermanyandRussiashould
alsoapplyinotherpost‐Communistpolities(e.g.Lithuania,Poland,Bulgaria,Albania).Bychoosinga
heterogeneoussample,Howardsolvestheproblemofrepresentativenessinhisrestrictedsample.However,this
sampleisdemonstrablynotrepresentativeacrossthepopulationoftheinference,whichisintendedtocoverall
countriesoftheworld.
Moreproblematicisthelackofvariationonkeycausalfactorsofinterest—Communismanditsputativecausal
pathways.Forthisreason,itisdifficulttoreachconclusionsaboutthecausalstatusofthesefactorsonthebasisof
themost‐differentanalysisalone.Itispossible,thatis,thatthethreecausalpathwaysidentifiedbyHowardalso
operatewithinpolitiesthatneverexperiencedCommunistrule.
Nordoesitseempossibletoconclusivelyeliminaterivalhypothesesonthebasisofthismost‐differentanalysis.
Indeed,thisisnotHoward'sintention.Hewishesmerelytoshowthatwhateverinfluenceoncivilsocietymightbe
attributedtoeconomic,cultural,andotherfactorsdoesnotexhaustthissubject.
Myconsideredjudgmentisthatthemost‐differentresearchdesignprovidesminimalleverageintotheproblemof
whyCommunistsystemsappeartosuppresscivicengagement,yearsaftertheirdisappearance.Fortunately,thisis
nottheonlyresearchdesignemployedbyHowardinhisadmirablestudy.Indeed,theauthoremploystwoother
small‐Ncross‐casemethods,aswellasalarge‐Ncross‐countrystatisticalanalysis.Thesemethodsdomostofthe
analyticwork.EastGermanymayberegardedasacausalpathwaycase(seeabove).Ithasalltheattributes
normallyassumedtofostercivicengagement(e.g.agrowingeconomy,multipartycompetition,civilliberties,afree
press,closeassociationwithWesternEuropeancultureandpolitics),butnonethelessshowslittleorno
improvementonthisdimensionduringthepost‐transitionera(Howard2003,8).Itisplausibletoattributethislack
ofchangetoitsCommunistpast,asHowarddoes,inwhichcaseEastGermanyshouldbeafruitfulcaseforthe
investigationofcausalmechanisms.ThecontrastbetweenEastandWestGermanyprovidesamost‐similar
analysissincethetwopolitiesshare(p.673) virtuallyeverythingexceptaCommunistpast.Thisvariationisalso
deftlyexploitedbyHoward.
Idonotwishtodismissthemost‐differentresearchmethodentirely.Surely,Howard'sfindingsarestrongerwiththe
intensiveanalysisofRussiathantheywouldbewithout.Yethisbookwouldnotstandsecurelyontheempirical
foundationprovidedbymost‐differentanalysisalone.Ifonestripsawaythepathway‐case(EastGermany)andthe
most‐similaranalysis(East/WestGermany)thereislittleleftuponwhichtobaseananalysisofcausalrelations
(asidefromthelarge‐Ncross‐nationalanalysis).Indeed,mostscholarswhoemploythemost‐differentmethoddo
soinconjunctionwithothermethods.20 Itisrarely,ifever,astandalonemethod.21
GeneralizingfromthisdiscussionofMarcHoward'swork,Iofferthefollowingsummaryremarksonthemost‐
differentmethodofcaseanalysis.(Ileaveasideissuesfacedbyallcase‐studyanalyses,issuesthatareexplored
inGerring2007.)
LetusbeginwithamethodologicalobstaclethatisfacedbybothMilleanstylesofanalysis—thenecessityof
dichotomizingeveryvariableintheanalysis.Recallthat,aswithmost‐similaranalysis,differencesacrosscases
mustgenerallybesizeableenoughtobeinterpretableinanessentiallydichotomousfashion(e.g.high/low,
present/absent)andsimilaritiesmustbecloseenoughtobeunderstoodasessentiallyidentical(e.g.high/high,
present/present).OtherwisetheresultsofaMilleanstyleanalysisarenotinterpretable.Theproblemof“degrees”
isdeadlyifthevariablesunderconsiderationare,bynature,continuous(e.g.GDP).Thisisaparticularconcernin
Howard'sanalysis,whereEastGermanyscoressomewhathigherthanRussiaincivicengagement;theyareboth
low,butRussiaisquiteabitlower.Howardassumesthatthisdivergenceisminimalenoughtobeunderstoodasa
differenceofdegreesratherthanofkinds,ajudgmentthatmightbequestioned.Intheserespects,most‐different
analysisisnomoresecure—butalsonoless—thanmost‐similaranalysis.
Inonerespect,most‐differentanalysisissuperiortomost‐similaranalysis.Ifthecodingassumptionsaresound,the
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most‐differentresearchdesignmaybequiteusefulforeliminatingnecessarycauses.Causalfactorsthatdonot
appearacrossthechosencases—e.g.X2a–d inTable28.4—areevidentlyunnecessaryfortheproductionofY.
However,itdoesnotfollowthatthemost‐differentmethodisthebestmethodforeliminatingnecessarycauses.
Notethatthedefiningfeatureofthismethodisthe(p.674) sharedelementacrosscases—X1inTable28.4.This
featuredoesnothelponetoeliminatenecessarycauses.Indeed,ifonewerefocusedsolelyoneliminating
necessarycausesonewouldpresumablyseekoutcasesthatregisterthesameoutcomesandhavemaximum
diversityonotherattributes.InTable28.4,thiswouldbeasetofcasesthatsatisfyconditionsX2a–d ,butnotX1.
Thus,eventhepresumedstrengthofthemost‐differentanalysisisnotsostrong.
Usually,case‐studyanalysisisfocusedontheidentification(orclarification)ofcausalrelations,nottheelimination
ofpossiblecauses.Inthissetting,themost‐differenttechniqueisuseful,butonlyifassumptionsofcausal
uniquenesshold.By“causaluniqueness,”Imeanasituationinwhichagivenoutcomeistheproductofonlyone
cause:YcannotoccurexceptinthepresenceofX.Xisnecessary,andinsomesituations(givencertain
backgroundconditions)sufficient,tocauseY.22
Considerthefollowinghypotheticalexample.Supposethatanewdisease,aboutwhichlittleisknown,has
appearedinCountryA.Therearehundredsofinfectedpersonsacrossdozensofaffectedcommunitiesinthat
country.InCountryB,locatedattheotherendoftheworld,severalnewcasesofthediseasesurfaceinasingle
community.Inthissetting,wecanimaginetwosortsofMilleananalyses.Thefirstexaminestwosimilarcommunities
withinCountryA,oneofwhichhasdevelopedthediseaseandtheotherofwhichhasnot.Thisisthemost‐similar
styleofcasecomparison,andfocusesaccordinglyontheidentificationofadifferencebetweenthetwocasesthat
mightaccountforvariationacrossthesample.Asecondapproachfocusesoncommunitieswherethediseasehas
appearedacrossthetwocountriesandsearchesforanysimilaritiesthatmightaccountforthesesimilaroutcomes.
Thisisthemost‐differentresearchdesign.
Bothareplausibleapproachestothisparticularproblem,andwecanimagineepidemiologistsemployingthem
simultaneously.However,themost‐differentdesigndemandsstrongerassumptionsabouttheunderlyingfactorsat
work.Itsupposesthatthediseasearisesfromthesamecauseinanysetting.Thisisoftenareasonableoperating
assumptionwhenoneisdealingwithnaturalphenomena,thoughtherearecertainlymanyexceptions.Death,for
example,hasmanycauses.Forthisreason,itwouldnotoccurtoustolookformost‐differentcasesofhigh
mortalityaroundtheworld.Inorderforthemost‐differentresearchdesigntoeffectivelyidentifyacausalfactorat
workinagivenoutcome,theresearchermustassumethatX1—thefactorheldconstantacrossthediversecases
—istheonlypossiblecauseofY(seeTable28.4).Thisassumptionrarelyholdsinsocial‐scientificsettings.Most
outcomesofinteresttoanthropologists,economists,politicalscientists,andsociologistshavemultiplecauses.
Therearemanywaystowinanelection,tobuildawelfarestate,togetintoawar,tooverthrowagovernment,or—
returningtoMarcHoward'swork—tobuildastrongcivilsociety.Anditisforthisreasonthatmost‐differentanalysis
israrelyappliedinsocialscienceworkand,whereapplied,israrelyconvincing.
Ifthisseemsatadsevere,thereisamorecharitablewayofapproachingthemost‐differentmethod.Arguably,this
isnotapure“method”atallbutmerelya(p.675) supplement,awayofincorporatingdiversityinthesub‐sample
ofcasesthatprovidetheunusualoutcomeofinterest.Iftheunusualoutcomeisrevolutions,onemightwishto
encompassawidevarietyofrevolutionsinone'sanalysis.Iftheunusualoutcomeispost‐Communistcivilsociety,it
seemsappropriatetoincludeadiversesetofpost‐Communistpolitiesinone'ssampleofcasestudies,asMarc
Howarddoes.Fromthisperspective,themost‐differentmethod(so‐called)mightbebetterlabeledadiverse‐case
method,asexploredabove.
10Conclusions
Inordertobeacaseofsomethingbroaderthanitself,thechosencasemustberepresentative(insomerespects)
ofalargerpopulation.Otherwise—ifitispurelyidiosyncratic(“unique”)—itisuninformativeaboutanythinglying
outsidethebordersofthecaseitself.Astudybasedonanonrepresentativesamplehasno(orverylittle)external
validity.Tobesure,nophenomenonispurelyidiosyncratic;thenotionofauniquecaseisamatterthatwouldbe
difficulttodefine.Oneisconcerned,asalways,withmattersofdegree.Casesaremoreorlessrepresentativeof
somebroaderphenomenonand,onthatscore,maybeconsideredbetterorworsesubjectsforintensiveanalysis.
(Theoneexception,asnoted,istheinfluentialcase.)
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Ofalltheproblemsbesettingcase‐studyanalysis,perhapsthemostpersistent—andthemostpersistently
bemoaned—istheproblemofsamplebias(AchenandSnidal1989;CollierandMahoney1996;Geddes1990;King,
Keohane,andVerba1994;Rohlfing2004;Sekhon2004).LisaMartin(1992,5)findsthattheoveremphasisof
internationalrelationsscholarsonafewwell‐knowncasesofeconomicsanctions—mostofwhichfailedtoelicit
anychangeinthesanctionedcountry—“hasdistortedanalystsviewofthedynamicsandcharacteristicsof
economicsanctions.”BarbaraGeddes(1990)chargesthatmanyanalysesofindustrialpolicyhavefocused
exclusivelyonthemostsuccessfulcases—primarilytheEastAsianNICs—leadingtobiasedinferences.Anna
BremanandCarolynShelton(2001)showthatcase‐studyworkonthequestionofstructuraladjustmentis
systematicallybiasedinsofarasresearcherstendtofocusondisastercases—thosewherestructuraladjustmentis
associatedwithverypoorhealthandhumandevelopmentoutcomes.Thesecases,oftenlocatedinsub‐Saharan
Africa,arebynomeansrepresentativeoftheentirepopulation.Consequently,scholarshiponthequestionof
structuraladjustmentishighlyskewedinaparticularideologicaldirection(againstneoliberalism)(seealsoGerring,
Thacker,andMoreno2005).
Theseexamplesmightbemultipliedmanytimes.Indeed,formanytopicsthemost‐studiedcasesareacknowledged
tobelessthanrepresentative.Itisworthreflectinguponthefactthatourknowledgeoftheworldisheavilycolored
byafew“big”(populous,rich,powerful)countries,andthatagoodportionofthedisciplinesofeconomics,
politicalscience,andsociologyarebuiltuponscholars'familiaritywith(p.676) theeconomics,politicalscience,
andsociologyofonecountry,theUnitedStates.23 Case‐studyworkisparticularlypronetoproblemsof
investigatorbiassincesomuchridesontheresearcher'sselectionofone(orafew)cases.Eveniftheinvestigator
isunbiased,hersamplemaystillbebiasedsimplybyvirtueof“random”error(whichmaybeunderstoodas
measurementerror,errorinthedata‐generationprocess,orasanunderlyingcausalfeatureoftheuniverse).
Thereareonlytwosituationsinwhichacase‐studyresearcherneednotbeconcernedwiththe
representativenessofherchosencase.Thefirstistheinfluentialcaseresearchdesign,whereacaseischosen
becauseofitspossibleinfluenceonacross‐casemodel,andhenceisnotexpectedtoberepresentativeofa
largersample.Thesecondisthedeviant‐casemethod,wherethechosencaseisemployedtoconfirmabroader
cross‐caseargumenttowhichthecasestandsasanapparentexception.Yetevenherethechosencaseis
expectedtoberepresentativeofabroadersetofcases—those,inparticular,thatarepoorlyexplainedbythe
extantmodel.
Inallothercircumstances,casesmustberepresentativeofthepopulationofinterestinwhateverwaysmightbe
relevanttothepropositioninquestion.Notethatwherearesearcherisattemptingtodisconfirmadeterministic
propositionthequestionofrepresentativenessisperhapsmoreappropriatelyunderstoodasaquestionof
classification:Isthechosencaseappropriatelyclassifiedasamemberofthedesignatedpopulation?Ifso,thenitis
fodderforadisconfirmingcasestudy.
Iftheresearcherisattemptingtoconfirmadeterministicproposition,ortomakeprobabilisticargumentsabouta
causalrelationship,thentheproblemofrepresentativenessisofthemoreusualsort:IscaseAunit‐homogeneous
relativetoothercasesinthepopulation?Thisisnotaneasymattertotest.However,inalarge‐Ncontextthe
residualforthatcase(inwhatevermodeltheresearcherhasgreatestconfidencein)isareasonableplacetostart.
Ofcourse,thistestisonlyasgoodasthemodelathand.Anyincorrectspecificationsorincorrectmodeling
procedureswilllikelybiastheresultsandgiveanincorrectassessmentofeachcase's“typicality.”Inaddition,
thereisthepossibilityofstochasticerror,errorsthatcannotbemodeledinageneralframework.Giventhe
explanatoryweightthatindividualcasesareaskedtobearinacase‐studyanalysis,itiswisetoconsidermore
thanjusttheresidualtestofrepresentativeness.Deductivelogicandanin‐depthknowledgeofthecasein
questionareoftenmorereliabletoolsthantheresultsofacross‐casemodel.
Inanycase,thereisnodispensingwiththequestion.Casestudies(withthetwoexceptionsalreadynoted)rest
uponanassumedsynecdoche:Thecaseshouldstandforapopulation.Ifthisisnottrue,orifthereisreasonto
doubtthisassumption,thentheutilityofthecasestudyisbroughtseverelyintoquestion.
Fortunately,thereissomesafetyinnumbers.Insofarascase‐studyevidenceiscombinedwithcross‐case
evidencetheissueofsamplebiasismitigated.Indeed,thesuspicionofcase‐studyworkthatonefindsinthesocial
sciencestodayis,inmyview,aproductofatoo‐literalinterpretationofthecase‐studymethod.Acasestudytout
(p.677) courtisthoughttomeanacasestudytoutseul.Insofarascasestudiesandcross‐casestudiescanbe
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enlistedwithinthesameinvestigation(eitherinthesamestudyorbyreferencetootherstudiesinthesame
subfield),problemsofrepresentativenessarelessworrisome.Thisisthevirtueofcross‐levelwork,a.k.a.
“triangulation.”
11Ambiguities
Beforeconcluding,Iwishtodrawattentiontotwoambiguitiesincase‐selectionstrategiesincase‐studyresearch.
Thefirstconcernstheadmixtureofseveralcase‐selectionstrategies.Thesecondconcernsthechangingstatus
ofacaseasastudyproceeds.
Somecasestudiesfollowonlyonestrategyofcaseselection.Theyaretypical,diverse,extreme,deviant,
influential,crucial,pathway,most‐similar,ormost‐differentresearchdesigns,asdiscussed.However,many
casestudiesmixandmatchamongthesecase‐selectionstrategies.Indeed,insofarasallcasestudiesseek
representativesamples,theyarealwaysinsearchof“typical”cases.Thus,itiscommonforwriterstodeclarethat
theircaseis,forexample,bothextremeandtypical;ithasanextremevalueonX1orYbutisnot,inother
respects,idiosyncratic.Thereisnotmuchthatonecansayaboutthesecombinationsofstrategiesexceptthat,
wherethecasesallowforavarietyofempiricalstrategies,thereisnoreasonnottopursuethem.Andwherethe
samecasescanserveseveralfunctionsatonce(withoutfurthereffortontheresearcher'spart),thereislittlecost
toamulti‐prongedapproachtocaseanalysis.
Thesecondissuethatdeservesemphasisisthechangingstatusofacaseduringthecourseofaresearcher's
investigation—whichmaylastforyears,ifnotdecades.Theproblemisacutewhereveraresearcherbeginsinan
exploratorymodeandproceedstohypothesis‐testing(thatis,shedevelopsaspecificX1/Yproposition)orwhere
theoperativehypothesisorkeycontrolvariablechanges(anewcausalfactorisdiscoveredoranotheroutcome
becomesthefocusofanalysis).Thingschange.Anditisthemarkofagoodresearchertokeephermindopento
newevidenceandnewinsights.Toooften,methodologicaldiscussionsgivethemisleadingimpressionthat
hypothesesareclearandremainfixedoverthecourseofastudy'sdevelopment.Nothingcouldbefurtherfromthe
truth.Theunofficialtranscriptsofacademia—accessibleininformalsettings,whereresearcherslettheirguards
down(particularlyifinebriated)—arefilledwithstoriesaboutdead‐ends,unexpectedfindings,anddrastically
revisedtheorychapters.Itwouldbeinteresting,inthisvein,tocomparepublishedworkwithdissertation
prospectusesandfellowshipapplications.Idoubtifthecorrelationbetweenthesetwostagesofresearchis
particularlystrong.
Research,afterall,isaboutdiscovery,notsimplytheverificationorfalsificationofstatichypotheses.Thatsaid,itis
alsotruethatresearchonaparticulartopicshouldmovefromhypothesisgeneratingtohypothesis‐testing.This
markstheprogressofa(p.678) field,andofascholar'sownwork.Asarule,researchthatbeginswithanopen‐
ended(X‐orY‐centered)analysisshouldconcludewithadeterminateX1/Yhypothesis.
Theproblemisthatresearchstrategiesthatareidealforexplorationarenotalwaysidealforconfirmation.The
extreme‐casemethodisinherentlyexploratorysincethereisnoclearcausalhypothesis;theresearcheris
concernedmerelytoexplorevariationonasingledimension(XorY).Othermethodscanbeemployedineitheran
open‐ended(exploratory)orahypothesis‐testing(confirmatory/disconfirmatory)mode.Thedifficultyisthatonce
theresearcherhasarrivedatadeterminatehypothesistheoriginallychosenresearchdesignmaynolonger
appeartobesowelldesigned.
Thisisunfortunate,butinevitable.Onecannotconstructtheperfectresearchdesignuntil(a)onehasaspecific
hypothesisand(b)oneisreasonablycertainaboutwhatoneisgoingtofind“outthere”intheempiricalworld.This
isparticularlytrueofobservationalresearchdesigns,butitalsoappliestomanyexperimentalresearchdesigns:
Usually,thereisa“good”(informative)finding,andafindingthatislessinsightful.Inshort,theperfectcase‐study
researchdesignisusuallyapparentonlyexpostfacto.
Therearethreewaystohandlethis.Onecanexplain,straightforwardly,thattheinitialresearchwasundertakenin
anexploratoryfashion,andthereforenotconstructedtotestthespecifichypothesisthatis—now—theprimary
argument.Alternatively,onecantrytoredesignthestudyafterthenew(orrevised)hypothesishasbeen
formulated.Thismayrequireadditionalfieldresearchorperhapstheintegrationofadditionalcasesorvariables
thatcanbeobtainedthroughsecondarysourcesorthroughconsultationofexperts.Afinalapproachistosimply
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jettison,orde‐emphasize,theportionofresearchthatnolongeraddressesthe(revised)keyhypothesis.Athree‐
casestudymaybecomeatwo‐casestudy,andsoforth.Losttimeandeffortarethecostsofthisdownsizing.
Intheevent,practicalconsiderationswillprobablydeterminewhichofthesethreestrategies,orcombinationsof
strategies,istobefollowed.(Theyarenotmutuallyexclusive.)Thepointtorememberisthatrevisionofone's
cross‐caseresearchdesignisnormalandperhapstobeexpected.Notalltwistsandturnsonthemeanderingtrail
oftruthcanbeanticipated.
12AreThereOtherMethodsofCaseSelection?
AttheoutsetofthischapterIsummarizedthetaskofcaseselectionasamatterofachievingtwoobjectives:
representativeness(typicality)andvariation(causalleverage).Evidently,thereareotherobjectivesaswell.For
example,onewishestoidentifycasesthatareindependentofeachother.Ifchosencasesareaffectedby(p.
679) eachother(sometimesknownasGalton'sproblemoraproblemofdiffusion),thisproblemmustbecorrected
beforeanalysiscantakeplace.Ihaveneglectedthisissuebecauseitisusuallyapparenttotheresearcherand,in
anycase,therearenosimpletechniquesthatmightbeutilizedtocorrectforsuchbiases.(Forfurtherdiscussion
ofthisandotherfactorsimpinginguponcaseselectionseeGerring2001,178–81.)
Ihavealsodisregardedpragmatic/logisticalissuesthatmightaffectcaseselection.Evidently,caseselectionis
ofteninfluencedbyaresearcher'sfamiliaritywiththelanguageofacountry,apersonalentréeintothatlocale,
specialaccesstoimportantdata,orfundingthatcoversonearchiveratherthananother.Pragmaticconsiderations
areoften—andquiterightly—decisiveinthecase‐selectionprocess.
Afinalconsiderationconcernsthetheoreticalprominenceofaparticularcasewithintheliteratureonasubject.
Researchersaresometimesobligedtostudycasesthathavereceivedextensiveattentioninpreviousstudies.
Thesearesometimesreferredtoas“paradigmatic”casesor“exemplars”(Flyvbjerg2004,427).
However,neitherpragmatic/logisticalutilitynortheoreticalprominencequalifiesasamethodologicalfactorincase
selection.Thatis,thesefeaturesofacasehavenobearingonthevalidityofthefindingsstemmingfromastudy.
Assuch,itisappropriatetogranttheseissuesaperipheralstatusinthischapter.
Onefinalcaveatmustbeissued.Whileitistraditionaltodistinguishamongthetasksofcaseselectionandcase
analysis,acloselookattheseprocessesshowsthemtobeindistinctandoverlapping.Onecannotchooseacase
withoutconsideringthesortofanalysisthatitmightbesubjectedto,andviceversa.Thus,thereadershould
considerchoosingcasesbyemployingtheninetechniqueslaidoutinthischapteralongwithanyconsiderations
thatmightbeintroducedbyvirtueofacase'squasi‐experimentalqualities,atopictakenupelsewhere(Gerring
2007,ch.6).
References
ABADIE,A.,DRUKKER,D.,HERR,J.L.,andIMBENS ,G.W.2001.Implementingmatchingestimatorsforaveragetreatment
effectsinStata.StataJournal,1:1–18.
ABBOTT,A.2001.TimeMatters:OnTheoryandMethod.Chicago:UniversityofChicagoPress.
—— andTSAY,A.2000.Sequenceanalysisandoptimalmatchingmethodsinsociology.SociologicalMethodsand
Research,29:3–33.
—— andFORREST,J.1986.Optimalmatchingmethodsforhistoricalsequences.JournalofInterdisciplinaryHistory,
16:471–94.
ACHEN,C.H.,andSNIDAL ,D.1989.Rationaldeterrencetheoryandcomparativecasestudies.WorldPolitics,41:
143–69.
ALLEN,W.S.1965.TheNaziSeizureofPower:TheExperienceofaSingleGermanTown,1930–1935.NewYork:
Watts.
Page 24 of 31
PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2015. All Rights
Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford
Handbooks Online for personal use (for details see Privacy Policy).
Subscriber: Minnesota State University, Mankato; date: 31 July 2015
Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
ALMOND,G.A.1956.Comparativepoliticalsystems.JournalofPolitics,18:391–409.
(p.680) AMENTA,E.1991.Makingthemostofacasestudy:theoriesofthewelfarestateandtheAmerican
experience.Pp.172–94inIssuesandAlternativesinComparativeSocialResearched.C.C.Ragin.Leiden:E.J.
Brill.
BARRO,R.J.1999.Determinantsofdemocracy.JournalofPoliticalEconomy,107:158–83.
BELSEY,D.A.,KUH,E.,andWELSCH,R.E.2004.RegressionDiagnostics:IdentifyingInfluentialDataandSourcesof
Collinearity.NewYork:Wiley.
BENNETT,A.,LEPGOLD,J.,andUNGER,D.1994.Burden‐sharinginthePersianGulfWar.InternationalOrganization,48:
39–75.
BENTLEY,A.1908/1967.TheProcessofGovernment.Cambridge,Mass.:HarvardUniversityPress.
BRADY,H.E.,andCOLLIER,D.(eds.)2004.RethinkingSocialInquiry:DiverseTools,SharedStandards.Lanham,Md.:
RowmanandLittlefield.
BRAUMOELLER,B.F.2003.Causalcomplexityandthestudyofpolitics.PoliticalAnalysis,11:209–33.
BREMAN,A.,andSHELTON,C.2001.Structuraladjustmentandhealth:aliteraturereviewofthedebate,itsrole‐players
andpresentedempiricalevidence.CMHWorkingPaperSeries,PaperNo.WG6:6.WHO,Commissionon
MacroeconomicsandHealth.
BRENNER,R.1976.Agrarianclassstructureandeconomicdevelopmentinpre‐industrialEurope.PastandPresent,
70:30–75.
BROWNE,A.1987.WhenBatteredWomenKill.NewYork:FreePress.
BUCHBINDER,S.,andVITTINGHOFF,E.1999.HIV‐infectedlong‐termnonprogressors:epidemiology,mechanismsof
delayedprogression,andclinicalandresearchimplications.MicrobesInfect,1:1113–20.
COHEN,M.R.,andNAGEL ,E.1934.AnIntroductiontoLogicandScientificMethod.NewYork:Harcourt,Braceand
Company.
COLLIER,D.,andMAHONEY,J.1996.Insightsandpitfalls:selectionbiasinqualitativeresearch.WorldPolitics,49:56–
91.
COLLIER,R.B.,andCOLLIER,D.1991/2002.ShapingthePoliticalArena:CriticalJunctures,theLaborMovement,and
RegimeDynamicsinLatinAmerica.NotreDame,Ind.:UniversityofNotreDamePress.
COLOMER,J.M.1991.Transitionsbyagreement:modelingtheSpanishway.AmericanPoliticalScienceReview,85:
1283–302.
CONVERSE,P.E.,andDUPEUX,G.1962.PoliticizationoftheelectorateinFranceandtheUnitedStates.PublicOpinion
Quarterly,16:1–23.
COPPEDGE,M.J.2004.TheconditionalimpactoftheeconomyondemocracyinLatinAmerica.Presentedatthe
conference“DemocraticAdvancementsandSetbacks:WhatHaveWeLearnt?”,UppsalaUniversity,June11–13.
DEFELICE,E.G.1986.Causalinferenceandcomparativemethods.ComparativePoliticalStudies,19:415–37.
DESCH,M.C.2002.Democracyandvictory:whyregimetypehardlymatters.InternationalSecurity,27:5–47.
DEYO,F.(ed.)1987.ThePoliticalEconomyoftheNewAsianIndustrialism.Ithaca,NY:CornellUniversityPress.
DION,D.1998.Evidenceandinferenceinthecomparativecasestudy.ComparativePolitics,30:127–45.
ECKSTEIN,H.1975.Casestudiesandtheoryinpoliticalscience.InHandbookofPoliticalScience,vii:Political
Science:ScopeandTheory,ed.F.I.GreensteinandN.W.Polsby.Reading,Mass.:Addison‐Wesley.
Page 25 of 31
PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2015. All Rights
Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford
Handbooks Online for personal use (for details see Privacy Policy).
Subscriber: Minnesota State University, Mankato; date: 31 July 2015
Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
(p.681) EGGAN,F.1954.Socialanthropologyandthemethodofcontrolledcomparison.AmericanAnthropologist,
56:743–63.
ELMAN,C.2003.LessonsfromLakatos.InProgressinInternationalRelationsTheory:AppraisingtheField,ed.C.
ElmanandM.F.Elman.Cambridge,Mass.:MITPress.
—— 2005.Explanatorytypologiesinqualitativestudiesofinternationalpolitics.InternationalOrganization,59:
293–326.
EMIGH,R.1997.Thepowerofnegativethinking:theuseofnegativecasemethodologyinthedevelopmentof
sociologicaltheory.TheoryandSociety,26:649–84.
EPSTEIN,L.D.1964.AcomparativestudyofCanadianparties.AmericanPoliticalScienceReview,58:46–59.
ERTMAN,T.1997.BirthoftheLeviathan:BuildingStatesandRegimesinMedievalandEarlyModernEurope.
Cambridge:CambridgeUniversityPress.
ESPING‐ ANDERSEN,G.1990.TheThreeWorldsofWelfareCapitalism.Princeton,NJ:PrincetonUniversityPress.
FLYVBJERG,B.2004.Fivemisunderstandingsaboutcase‐studyresearch.Pp.420–34inQualitativeResearch
Practice,ed.C.Seale,G.Gobo,J.F.Gubrium,andD.Silverman.London:Sage.
GEDDES ,B.1990.Howthecasesyouchooseaffecttheanswersyouget:selectionbiasincomparativepolitics.In
PoliticalAnalysis,vol.ii,ed.J.A.Stimson.AnnArbor:UniversityofMichiganPress.
—— 2003.ParadigmsandSandCastles:TheoryBuildingandResearchDesigninComparativePolitics.Ann
Arbor:UniversityofMichiganPress.
GEORGE,A.L.,andBENNETT,A.2005.CaseStudiesandTheoryDevelopment.Cambridge,Mass.:MITPress.
—— andSMOKE,R.1974.DeterrenceinAmericanForeignPolicy:TheoryandPractice.NewYork:Columbia
UniversityPress.
GERRING,J.2001.SocialScienceMethodology:ACriterialFramework.Cambridge:CambridgeUniversityPress.
—— 2007.CaseStudyResearch:PrinciplesandPractices.Cambridge:CambridgeUniversityPress.
—— THACKER,S.andMORENO,C.2005.Doneoliberalpoliciessavelives?Unpublishedmanuscript.
GOERTZ,G.andSTARR,H.(eds.)2003.NecessaryConditions:Theory,MethodologyandApplications.NewYork:
RowmanandLittlefield.
—— andLEVY,J.(eds.)forthcoming.Causalexplanations,necessaryconditions,andcasestudies:WorldWarIand
theendoftheColdWar.Manuscript.
GOODIN,R.E.andSMITSMAN,A.2000.Placingwelfarestates:theNetherlandsasacrucialtestcase.Journalof
ComparativePolicyAnalysis,2:39–64.
GUJARATI,D.N.2003.BasicEconometrics,4thedn.NewYork:McGraw‐Hill.
HAMILTON,G.G.1977.Chineseconsumptionofforeigncommodities:acomparativeperspective.American
SociologicalReview,42:877–91.
HAYNES ,B.F.PANTALEO,G.andFAUCI,A.S.1996.Towardanunderstandingofthecorrelatesofprotectiveimmunityto
HIVinfection.Science,271:324–8.
HEMPEL ,C.G.1942.Thefunctionofgenerallawsinhistory.JournalofPhilosophy,39:35–48.
HO,D.E.IMAI,K.KING,G.andSTUART,E.A.2004.Matchingasnonparametricpreprocessingforreducingmodel
dependenceinparametriccausalinference.Manuscript.
HOWARD,M.M.2003.TheWeaknessofCivilSocietyinPost‐CommunistEurope.Cambridge:CambridgeUniversity
Page 26 of 31
PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2015. All Rights
Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford
Handbooks Online for personal use (for details see Privacy Policy).
Subscriber: Minnesota State University, Mankato; date: 31 July 2015
Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
Press.
(p.682) HOWSON,C.andURBACH,P.1989.ScientificReasoning:TheBayesianApproach.LaSalle,Ill.:OpenCourt.
HUMPHREYS ,M.2005.Naturalresources,conflict,andconflictresolution:uncoveringthemechanisms.Journalof
ConflictResolution,49:508–37.
JENICEK,M.2001.ClinicalCaseReportinginEvidence‐BasedMedicine,2ndedn.Oxford:OxfordUniversityPress.
KARL ,T.L.1997.TheParadoxofPlenty:OilBoomsandPetro‐states.Berkeley:UniversityofCaliforniaPress.
KAZANCIGIL ,A.1994.Thedeviantcaseincomparativeanalysis:highstatenessincomparativeanalysis.Pp.213–38
inComparingNations:Concepts,Strategies,Substance,ed.M.DoganandA.Kazancigil.Cambridge:Blackwell.
KEMP,K.A.1986.Race,ethnicity,classandurbanspatialconflict:ChicagoasacrucialcaseUrbanStudies,23:
197–208.
KENDALL ,P.L.andWOLF,K.M.1949/1955.Theanalysisofdeviantcasesincommunicationsresearch.In
CommunicationsResearch,1948–1949,ed.P.F.LazarsfeldandF.N.Stanton.NewYork:HarperandBrothers.
Reprintedaspp.167–70inTheLanguageofSocialResearch,ed.P.F.LazarsfeldandM.Rosenberg.NewYork:
FreePress.
KENNEDY,C.H.2005.Single‐caseDesignsforEducationalResearch.Boston:AllynandBacon.
KENNEDY,P.2003.AGuidetoEconometrics,5thedn.Cambridge,Mass.:MITPress.
KHONG,Y.F.1992.AnalogiesatWar:Korea,Munich,DienBienPhu,andtheVietnamDecisionsof1965.Princeton,
NJ:PrincetonUniversityPress.
KING,G.KEOHANE,R.O.andVERBA,S.1994.DesigningSocialInquiry:ScientificInferenceinQualitativeResearch.
Princeton,NJ:PrincetonUniversityPress.
LAKATOS ,I.1978.TheMethodologyofScientificResearchProgrammes.Cambridge:CambridgeUniversityPress.
LAZARSFELD,P.F.andBARTON,A.H.1951.Qualitativemeasurementinthesocialsciences:classification,typologies,
andindices.InThePolicySciences,ed.D.LernerandH.D.Lass‐well.Stanford,Calif.:StanfordUniversityPress.
LEVY,J.S.2002.Qualitativemethodsininternationalrelations.InEvaluatingMethodologyinInternationalStudies,
ed.F.P.HarveyandM.Brecher.AnnArbor:UniversityofMichiganPress.
LIJPHART,A.1968.ThePoliticsofAccommodation:PluralismandDemocracyintheNetherlands.Berkeley:
UniversityofCaliforniaPress.
—— 1969.Consociationaldemocracy.WorldPolitics,21:207–25.
—— 1971.Comparativepoliticsandthecomparativemethod.AmericanPoliticalScienceReview,65:682–93.
—— 1975.Thecomparablecasesstrategyincomparativeresearch.ComparativePoliticalStudies,8:158–77.
LIPSET,S.M.1959.Somesocialrequisitesofdemocracy:economicdevelopmentandpoliticaldevelopment.
AmericanPoliticalScienceReview,53:69–105.
—— 1960/1963.PoliticalMan:TheSocialBasesofPolitics.GardenCity,NY:Anchor.
—— 1968.AgrarianSocialism:TheCooperativeCommonwealthFederationinSaskatchewan.AStudyinPolitical
Sociology.GardenCity,NY:Doubleday.
—— TROW,M.A.andCOLEMAN,J.S.1956.UnionDemocracy:TheInternalPoliticsoftheInternational
TypographicalUnion.NewYork:FreePress.
LYND,R.S.andLYND,H.M.1929/1956.Middletown:AStudyinAmericanCulture.NewYork:Harcourt,Brace.
Page 27 of 31
PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2015. All Rights
Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford
Handbooks Online for personal use (for details see Privacy Policy).
Subscriber: Minnesota State University, Mankato; date: 31 July 2015
Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
MAHONEY,J.andGOERTZ,G.2004.Thepossibilityprinciple:choosingnegativecasesincomparativeresearch.
AmericanPoliticalScienceReview,98:653–69.
(p.683) MARTIN,L.L.1992.CoerciveCooperation:ExplainingMultilateralEconomicSanctions.Princeton,NJ:
PrincetonUniversityPress.
MAYO,D.G.1996.ErrorandtheGrowthofExperimentalKnowledge.Chicago:UniversityofChicagoPress.
MECKSTROTH,T.1975.“Mostdifferentsystems”and“mostsimilarsystems:”astudyinthelogicofcomparative
inquiry.ComparativePoliticalStudies,8:133–77.
MIGUEL ,E.2004.Tribeornation:nation‐buildingandpublicgoodsinKenyaversusTanzania.WorldPolitics,56:
327–62.
MILL ,J.S.1843/1872.TheSystemofLogic,8thedn.London:Longmans,Green.
MONROE,K.R.1996.TheHeartofAltruism:PerceptionsofaCommonHumanity.Princeton,NJ:PrincetonUniversity
Press.
MOORE,B.,JR.1966.SocialOriginsofDictatorshipandDemocracy:LordandPeasantintheMakingoftheModern
World.Boston:BeaconPress.
MORGAN,S.L.andHARDING,D.J.2005.Matchingestimatorsofcausaleffects:fromstratificationandweightingto
practicaldataanalysisroutines.Manuscript.
MOULDER,F.V.1977.Japan,ChinaandtheModernWorldEconomy:TowardaReinterpretationofEastAsian
Developmentca.1600toca.1918.Cambridge:CambridgeUniversityPress.
MUNCK,G.L.2004.Toolsforqualitativeresearch.Pp.105–21inRethinkingSocialInquiry:DiverseTools,Shared
Standards,ed.H.E.BradyandD.Collier.Lanham,Md.:RowmanandLittlefield.
NJOLSTAD,O.1990.Learningfromhistory?Casestudiesandthelimitstotheory‐building.Pp.220–46inArmsRaces:
TechnologicalandPoliticalDynamics,ed.O.Njolstad.ThousandOaks,Calif.:Sage.
PATTON,M.Q.2002.QualitativeEvaluationandResearchMethods.NewburyPark,Calif.:Sage.
POPPER,K.1934/1968.TheLogicofScientificDiscovery.NewYork:HarperandRow.
—— 1963.ConjecturesandRefutations.London:RoutledgeandKeganPaul.
POSNER,D.2004.Thepoliticalsalienceofculturaldifference:whyChewasandTumbukasarealliesinZambiaand
adversariesinMalawi.AmericanPoliticalScienceReview,98:529–46.
PRZEWORSKI,A.andTEUNE,H.1970.TheLogicofComparativeSocialInquiry.NewYork:JohnWiley.
QUEEN,S.1928.Roundtableonthecasestudyinsociologicalresearch.PublicationsoftheAmericanSociological
Society,PapersandProceedings,22:225–7.
RAGIN,C.C.2000.Fuzzy‐setSocialScience.Chicago:UniversityofChicagoPress.
—— 2004.Turningthetables.Pp.123–38inRethinkingSocialInquiry:DiverseTools,SharedStandards,ed.H.E.
BradyandD.Collier.Lanham,Md.:RowmanandLittlefield.
REILLY,B.2000–1.Democracy,ethnicfragmentation,andinternalconflict:confusedtheories,faultydata,andthe
“crucialcase”ofPapuaNewGuinea.InternationalSecurity,25:162–85.
—— andPHILLPOT,R.2003.“Makingdemocracywork”inPapuaNewGuinea:socialcapitalandprovincial
developmentinanethnicallyfragmentedsociety.AsianSurvey,42:906–27.
ROGOWSKI,R.1995.Theroleoftheoryandanomalyinsocial‐scientificinference.AmericanPoliticalScience
Review,89:467–70.
Page 28 of 31
PRINTED FROM OXFORD HANDBOOKS ONLINE (www.oxfordhandbooks.com). (c) Oxford University Press, 2015. All Rights
Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single chapter of a title in Oxford
Handbooks Online for personal use (for details see Privacy Policy).
Subscriber: Minnesota State University, Mankato; date: 31 July 2015
Case Selection for Case‐Study Analysis: Qualitative and Quantitative Techniques
ROHLFING,I.2004.Haveyouchosentherightcase?Uncertaintyincaseselectionforsinglecasestudies.Working
Paper,InternationalUniversity,Bremen.
ROSENBAUM,P.R.2004.Matchinginobservationalstudies.InAppliedBayesianModelingandCausalInferencefrom
anIncomplete‐dataPerspective,ed.A.GelmanandX.‐L.Meng.NewYork:JohnWiley.
—— andSILBER,J.H.2001.Matchingandthickdescriptioninanobservationalstudyofmortalityaftersurgery.
Biostatistics,2:217–32.
ROSS ,M.2001.Doesoilhinderdemocracy?WorldPolitics,53:325–61.
(p.684) SAGAN,S.D.1995.LimitsofSafety:Organizations,Accidents,andNuclearWeapons.Princeton,NJ:
PrincetonUniversityPress.
SEKHON,J.S.2004.Qualitymeetsquantity:casestudies,conditionalprobabilityandcounter‐factuals.Perspectives
inPolitics,2:281–93.
SHAFER,M.D.1988.DeadlyParadigms:TheFailureofU.S.CounterinsurgencyPolicy.Princeton,NJ:Princeton
UniversityPress.
SKOCPOL ,T.1979.StatesandSocialRevolutions:AComparativeAnalysisofFrance,Russia,andChina.
Cambridge:CambridgeUniversityPress.
—— andSOMERS ,M.1980.Theusesofcomparativehistoryinmacrosocialinquiry.ComparativeStudiesinSociety
andHistory,22:147–97.
STINCHCOMBE,A.L.1968.ConstructingSocialTheories.NewYork:Harcourt,Brace.
SWANK,D.H.2002.GlobalCapital,PoliticalInstitutions,andPolicyChangeinDevelopedWelfareStates.
Cambridge:CambridgeUniversityPress.
TENDLER,J.1997.GoodGovernmentintheTropics.Baltimore:JohnsHopkinsUniversityPress.
TRUMAN,D.B.1951.TheGovernmentalProcess.NewYork:AlfredA.Knopf.
TSAI,L.2007.AccountabilitywithoutDemocracy:HowSolidaryGroupsProvidePublicGoodsinRuralChina.
Cambridge:CambridgeUniversityPress.
VANEVERA,S.1997.GuidetoMethodsforStudentsofPoliticalScience.Ithaca,NY:CornellUniversityPress.
WAHLKE,J.C.1979.Pre‐behavioralisminpoliticalscience.AmericanPoliticalScienceReview,73:9–31.
YASHAR,D.J.2005.ContestingCitizenshipinLatinAmerica:TheRiseofIndigenousMovementsandthe
PostliberalChallenge.Cambridge:CambridgeUniversityPress.
YIN,R.K.2004.CaseStudyAnthology.ThousandOaks,Calif.:Sage.
Notes:
(1)Gujarati(2003);Kennedy(2003).Interestingly,thepotentialofcross‐casestatisticsinhelpingtochoosecases
forin‐depthanalysisisrecognizedinsomeoftheearliestdiscussionsofthecase‐studymethod(e.g.Queen1928,
226).
(2)ThisexpandsonMill(1843/1872,253),whowroteofscientificenquiryastwofold:“eitherinquiriesintothe
causeofagiveneffectorintotheeffectsorpropertiesofagivencause.”
(3)Thismethodhasnotreceivedmuchattentiononthepartofqualitativemethodologists;hence,theabsenceofa
generallyrecognizedname.ItbearssomeresemblancetoJ.S.Mill'sJointMethodofAgreementandDifference(Mill
1843/1872),whichistosayamixtureofmost‐similarandmost‐differentanalysis,asdiscussedbelow.Patton
(2002,234)employstheconceptof“maximumvariation(heterogeneity)sampling.”
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(4)Moreprecisely,GeorgeandSmoke(1974,534,522–36,ch.18;seealsodiscussioninCollierandMahoney
1996,78)setouttoinvestigatecausalpathwaysanddiscovered,throughthecourseoftheirinvestigationofmany
cases,thesethreecausaltypes.Yet,forourpurposeswhatisimportantisthatthefinalsampleincludesatleast
onerepresentativeofeach“type.”
(5)ForfurtherexamplesseeCollierandMahoney(1996);Geddes(1990);Tendler(1997).
(6)Traditionally,methodologistshaveconceptualizedcasesashaving“positive”or“negative”values(e.g.Emigh
1997;MahoneyandGoertz2004;Ragin2000,60;2004,126).
(7)Geddes(1990);King,Keohane,andVerba(1994).SeealsodiscussioninBradyandCollier(2004);Collierand
Mahoney(1996);Rogowski(1995).
(8)Theexceptionwouldbeacircumstanceinwhichtheresearcherintendstodisproveadeterministicargument
(Dion1998).
(9)Geddes(2003,131).Forotherexamplesofcaseworkfromtheannalsofmedicinesee“Clinicalreports”inthe
Lancet,“Casestudies”inCanadianMedicalAssociationJournal,andvariousissuesoftheJournalofObstetrics
andGynecology,oftendevotedtoclinicalcases(discussedinJenicek2001,7).Forexamplesfromthesubfieldof
comparativepoliticsseeKazancigil(1994).
(10)ForadiscussionoftheimportantroleofanomaliesinthedevelopmentofscientifictheorizingseeElman
(2003);Lakatos(1978).Forexamplesofdeviant‐caseresearchdesignsinthesocialsciencesseeAmenta(1991);
Coppedge(2004);Eckstein(1975);Emigh(1997);KendallandWolf(1949/1955).
(11)Forexamplesofthecrucial‐casemethodseeBennett,Lepgold,andUnger(1994);Desch(2002);Goodinand
Smitsman(2000);Kemp(1986);ReillyandPhillpot(2003).ForgeneraldiscussionseeGeorgeandBennett(2005);
Levy(2002);Stinchcombe(1968,24–8).
(12)Athirdposition,whichpurportstobeneitherPopperianorBayesian,hasbeenarticulatedbyMayo(1996,ch.
6).Fromthisperspective,thesameideaisarticulatedasamatterof“severetests.”
(13)ItshouldbenotedthatTsai'sconclusionsdonotrestsolelyonthiscrucialcase.Indeed,sheemploysabroad
rangeofmethodologicaltools,encompassingcase‐studyandcross‐casemethods.
(14)SeealsothediscussioninEckstein(1975)andLijphart(1969).Foradditionalexamplesofcasestudies
disconfirminggeneralpropositionsofadeterministicnatureseeAllen(1965);Lipset,Trow,andColeman(1956);
Njolstad(1990);Reilly(2000–1);anddiscussioninDion(1998);Rogowski(1995).
(15)Granted,insofarascase‐studyanalysisprovidesawindowintocausalmechanisms,andcausalmechanisms
areintegraltoagiventheory,asinglecasemaybeenlistedtoconfirmordisconfirmaproposition.However,ifthe
casestudyupholdsapositedpatternofX/Ycovariation,andfindsfaultonlywiththestipulatedcausalmechanism,
itwouldbemoreaccuratetosaythatthestudyforcesthereformulationofagiventheory,ratherthanits
confirmationordisconfirmation.Seefurtherdiscussioninthefollowingsection.
(16)Sometimes,themost‐similarmethodisknownasthe“methodofdifference,”afteritsinventor(Mill1843/1872).
ForlatertreatmentsseeCohenandNagel(1934);Eggan(1954);Gerring(2001,ch.9);Lijphart(1971;1975);
Meckstroth(1975);PrzeworskiandTeune(1970);SkocpolandSomers(1980).
(17)ForgoodintroductionsseeHoetal.(2004);MorganandHarding(2005);Rosenbaum(2004);Rosenbaumand
Silber(2001).ForadiscussionofmatchingproceduresinStataseeAbadieetal.(2001).
(18)Themost‐differentmethodisalsosometimesreferredtoasthe“methodofagreement,”followingitsinventor,
J.S.Mill(1843/1872).SeealsoDeFelice(1986);Gerring(2001,212–14);Lijphart(1971;1975);Meckstroth(1975);
PrzeworskiandTeune(1970);SkocpolandSomers(1980).ForexamplesofthismethodseeCollierandCollier
(1991/2002);ConverseandDupeux(1962);Karl(1997);Moore(1966);Skocpol(1979);Yashar(2005,23).
However,mostofthesestudiesaredescribedascombiningmost‐similarandmost‐differentmethods.
(19)InthefollowingdiscussionItreatthetermssocialcapital,civilsociety,andcivicengagementinterchangeably.
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(20)E.g.CollierandCollier(1991/2002);Karl(1997);Moore(1966);Skocpol(1979);Yashar(2005,23).Karl
(1997),whichaffectstobeamost‐differentsystemanalysis(20),isaparticularlyclearexampleofthis.Herstudy,
focusedostensiblyonpetro‐states(stateswithlargeoilreserves),makestwosortsofinferences.Thefirst
concernsthe(usually)obstructiveroleofoilinpoliticalandeconomicdevelopment.Thesecondsortofinference
concernsvariationwithinthepopulationofpetro‐states,showingthatsomecountries(e.g.Norway,Indonesia)
managetoavoidthepathologiesbroughtonelsewherebyoilresources.Whenattemptingtoexplainthe
constrainingroleofoilonpetro‐states,Karlusuallyreliesoncontrastsbetweenpetro‐statesandnonpetro‐states
(e.g.ch.10).Onlywhenattemptingtoexplaindifferencesamongpetro‐statesdoessherestricthersampleto
petro‐states.Inmyopinion,verylittleuseismadeofthemost‐differentresearchdesign.
(21)Thiswasrecognized,atleastimplicitly,byMill(1843/1872,258–9).Skepticismhasbeenechoedby
methodologistsintheinterveningyears(e.g.CohenandNagel1934,251–6;Gerring2001;SkocpolandSomers
1980).Indeed,explicitdefensesofthemost‐differentmethodarerare(butseeDeFelice1986).
(22)AnotherwayofstatingthisistosaythatXisa“nontrivialnecessarycondition”ofY.
(23)Wahlke(1979,13)writesofthefailingsofthe“behavioralist”modeofpoliticalscienceanalysis:“Itrarelyaims
atgeneralization;researcheffortshavebeenconfinedessentiallytocasestudiesofsinglepoliticalsystems,most
ofthemdealing…withtheAmericansystem.”
JohnGerring
JohnGerringisProfessorofPoliticalScience,BostonUniversity.
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