教育研究因果比较研究

EducationalResearch:Causal-ComparativeStudiesEDU8603EducationalResearchRichardM.Jacobs,OSA,Ph.D.Research...Thesystematicapplicationofafamilyofmethodsemployedtoprovidetrustworthyinformationaboutproblems…anongoingprocessbasedonmanyaccumulatedunderstandingsandexplanationsthat,whentakentogetherleadtogeneralizationsaboutproblemsandthedevelopmentoftheoriesThebasicstepsofresearch...Scientificanddisciplinedinquiryisanorderlyprocess,involving:

descriptionandexecutionofprocedurestocollectioninformation(“method”)

objectivedataanalysis

statementoffindings(“results”)

recognitionandidentificationofatopictobestudied(“problem”)Researchmethods...Quantitative……collectsandanalyzesnumericaldataobtainedfromformalinstrumentsQuantitativemethods...descriptiveresearch(“surveyresearch”)correlationalresearchcausal-comparativeresearch(“expostfactoresearch”)experimentalresearchcausal-comparativeresearch(“expostfactoresearch”)…atleasttwodifferentgroupsarecomparedonadependentvariableormeasureofperformance(calledthe“effect”)becausetheindependentvariable(calledthe“cause”)hasalreadyoccurredorcannotbemanipulatedResearchvariables...Independent……anactivityofcharacteristicbelievedtomakeadifferencewithrespecttosomebehavior…(syn.)experimentalvariable,cause,treatmentdependentvariable……thechangeordifferenceoccurringasaresultoftheindependentvariable…(syn.)criterionvariable,effect,outcome,posttestAcausal-comparativestudy……astudyinwhichtheresearcherattemptstodeterminethecause,orreason,forpre-existingdifferencesingroupsofindividuals…calledan“expostfacto”studybecauseboththeeffectandtheallegedcausehavealreadyoccurredandmustbestudiedinretrospectDifferencesincausal-comparisonandcorrelationalstudies…causal-comparativestudies……attempttoidentifycause-effectrelationshipscorrelationalstudies……attempttoidentifyrelationshipscausal-comparativestudies……involvetwo(ormore)groupsandoneindependentvariablecorrelationalstudies……typicallyinvolvetwo(ormore)variablesandonegroupcausal-comparativestudies……involvemakingcomparisonscorrelationalstudies……involveestablishingrelationshipsDifferencesincausal-comparisonandexperimentalstudies…causal-comparativestudies……individualsarenotrandomlyselectedbutselectedbecausetheybelongtogroupsexperimentalstudies……individualsarerandomlyselectedandassignedtotwo(ormore)groupscausal-comparativestudies……theresearchercannotmanipulatetheindependentvariableexperimentalstudies……theresearchermanipulatestheindependentvariablecausal-comparativestudies……theindependentvariablehasalreadyoccurredandcannotbemanipulatedexperimentalstudies……theresearchermanipulatestheindependentvariabletodetermineitseffectscausal-comparativestudies……therandomsampleisselectedfromtwoalready-existingpopulationsexperimentalstudies……therandomsampleisselectedfromasinglepopulationConductingacausal-comparativestudy…1.selecttheproblem2.selectparticipantsandinstrument3.designandprocedure4.dataanalysisandinterpretation1.selecttheproblem……theresearcherstartswithaneffectandseeksitscauses…theindependentvariablecannotorshouldnotbemanipulated2.selecttheparticipantsandinstrument……selectsamplesrepresentativeoftheirrespectivepopulationsandsimilarwithrespecttocriticalvariablesotherthantheindependentvariable…called“comparisongroups”3.designandprocedure……theperformanceofthegroupsiscomparedusingsomevaliddependentvariablemeasure(“instrument”)…lackofrandomization,manipulation,andcontrolaresourcesofweaknesscontrol…theprocessbywhichtheresearcherattemptstoensurethatthefindingsareasfreeofresearcherbiasanderroraspossibletypesofcontrol…randomassignmentofparticipantstogroups…pair-wisematching…comparinghomogeneousgroups…comparinghomogeneoussubgroups…factorialanalysisofvariance…analysisofcovariancerandomassignmentofparticipantstogroups…notpossibleincausal-comparativestudiesbecausethegroupsalreadyexistandhavealreadyreceivedthetreatmentpair-wisematching…first:findaparticipantinthesecond(third,fourth,etc.)groupwiththesameorsimilarscoreonthecontrol(nonmanipulated)variableastheparticipantinthefirstgroup…second:ifaparticipantineithergroupdoesnothaveasuitablematch,theparticipantiseliminatedfromthestudycomparinghomogeneousgroups…controlforextraneousvariablesthatarehomogeneouswithrespecttotheextraneousvariables…limitation:lowersthenumberofparticipantsinthestudyand,ofcourse,limitsthegeneralizabilityofthefindingscomparinghomogeneoussubgroups…formsubgroupswithineachgroupthatrepresentalllevelsofthecontrol(nonmanipulated)variable…controlsforthevariableandalsopermitstheresearchertodeterminewhethertheindependentvariableaffectsthedependentvariabledifferentlyatdifferentlevelsofthecontrol(nonmanipulated)variablefactorialanalysisofvariance(“FANOVA”)…buildingthecontrol(nonmanipulated)variableintotheresearchdesign…thenuseFANOVAtoanalyzetheresultstodeterminetheeffectoftheindependentandcontrol(nonmanipulated)variableonthedependentvariable,bothseparatelyandincombination…FANOVAallowstheresearchertodetermineifthereisaninteractionbetweentheindependentvariableandthedependentvariablesuchthattheindependentvariableoperatesdifferentlyatdifferentlevelsoftheindependentvariablebuildingitintotheresearchdesignanalysisofcovariance(“ANCOVA”)…statisticallyadjustsinitialgroupdifferencesonadependentvariableforinitialdifferencesonsomeothervariablerelatedtoperformanceonthedependentvariable…removesinitialdifferencessothattheresultscanbefairlycomparedasifthetwogroupsstartedequallysymbolicrepresentationofthebasiccausal-comparativedesignIndependentDependentGroup

Variable

Variable(E)(X) O(C) OWhere:E(experimentalgroup);C(controlgroup);X(independentvariable);O(dependentvariable)IndependentDependentGroup

Variable

Variable(E) (X1) O(C) (X2) OWhere:E(experimentalgroup);C(controlgroup);X(independentvariable);O(dependentvariable)4.Dataanalysisandinterpretation……researcherusesavarietyofdescriptiveandinferentialstatistics:meanstandard

deviationt-testanalysisofvariancechisquaredmean…thedescriptivestatisticindicatingtheaverageperformanceofanindividualorgrouponameasureofsomevariablestandarddeviation…thedescriptivestatisticindicatingthespreadofasetofscoresaroundthemeant-test…theinferentialstatisticindicatingwhetherthemeansoftwogroupsaresignificantlydifferentfromoneanotheranalysisofvariance(“ANOVA”)…theinferentialstatisticindicatingthepresenceofasignificantdifferenceamongthemeansofthreeormoregroupschisquared(Χ2)…theinferentialstatisticindicatingthatthereisagreaterthanexpecteddifferenceamonggroupfrequenciesMini-Quiz…Trueandfalse……causal-comparativestudiesattempttoidentifythecause-effectrelationships;correlationalstudiesdonotTrue…causal-comparativestudiestypicallyinvolvetwo(ormore)groupsandoneindependentvariable,whereascorrelationalstudiestypicallyinvolvetwo(ormore)variablesandonegroupTrue…causal-comparativestudiesinvolverelation,whereascorrelationalstudiesinvolvecauseFalse…oftentimes,causal-comparativeresearchisundertakenbecausetheindependentvariablecouldbemanipulatedbutshouldnotTrue…oneofthemostimportantreasonsforconductingcausal-comparativeresearchistoidentifyvariablesworthyofexperimentalinvestigationTrue…“lackofcontrol”meansthattheresearchercanandshouldmanipulatetheindependentvariableFalse…eachgroupinacausal-comparativestudyrepresentsadifferentpopulationTrue…themoresimilartwogroupsareonallrelevantvariablesexcepttheindependentvariable,thestrongerthestudyisTrue…thereisrandomassignmenttotreatmentgroupsfromasinglepopulationincausal-comparativestudiesFalse…lackofrandomization,manipulationoftheindependentvariable,andcontrolareallsourcesofweaknessinacausal-comparativedesignTrue…matching,comparinghomogenousgroupsorsubgroups,andcovariateanalysisarestrategiesthatenableresearcherstoovercomeproblemsofinitialgroupdifferencesonanextraneousvariableTrue…interpretationofthefindingsinacausal-comparativestudyrequiresconsiderablecautionbecausethecausemaybetheeffectandtheeffectmaybethecauseTrue…extraneousvariablesorconfoundingfactorsmaybethereal“cause”ofboththeindependentanddependentvariablesTrueFillintheblank……groupsselectedforacausal-comparativestudywhichdifferonsomeindependentvariableandcomparingthemonsomedependentvariablecomparisongroupsFillintheblank……unexplainedvariablesthatinfluenceadependentvariableconfoundingfactorsextraneousvariablesFillintheblank……amethodforcontrollingextraneousvariablesbycomparinggroupsthatarehomogeneouswithrespecttotheextraneousvariablecomparinghomogeneousgroupsFillintheblank……amethodforcontrollingextraneousvariablesbyformingsubgroupswithineachgroupthatrepresentalllevelsofthecontrolvariablecomparinghomogeneoussubgroupsFillintheblank……astatisticaltooltodeterminetheeffectsoftheindependentvariableandthecontrolvariableonthedependentvariable,bothseparatelyandincombinationfactorialanalysisofvarianceFillintheblank……astatisticaltooltoadjustinitialgroupdifferencesonvariablesanalysisofcovarianceFillintheblank…