experimental study1

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1、ExperimentalStudy主讲：孙媛11.Whatisanexperimentalmethod?Experimentswerefirstusedinthenaturalsciences.Allofushavehadtheexperienceofundertakingeitheraphysicalorchemicalexperimentinalaboratory.Whathaveleftinyourmemorybytheseexperimentsaretubes,chemicals,wiresandothermaterials.Whatis

2、anexperimentinasocialscience?Iwillanswerthisquestionfirstbyaconceptualdefinition.22.DefinitionTheexperimentalmethodisascientificmethodthatchangesgraduallyconditionsinplanunderacertaincontrol,andaccordingtoobservationrecordsandresearchdata,determinesthecausalitybetweenconditio

3、nsandthephenomenonbymeasuringtheaccompanyingphenomenaandchanges,thenfindsandsummariestheobjectivelawsofSecondLanguageAcquisition.33.ThebasicpremiseofanexperimentThebasicpremiseofanexperimentisthatallfactorssaveoneareheldconstant.Thesinglefactorisvariedtoseewhateffectithasonth

4、ephenomenonunderinvestigation.Asstatedearlier,experimentshavetwocriteria:①thereareatleasttwogroupsincludedinthestudy,acontrolgroupandanexperimentalgroup;②thesubjectsarerandomlyassignedtooneofthosegroups.45.Whydowehavetwogroups?Thepurposeofhavingthetwogroupsinthestudyisthatifo

5、negroupistreatedinonemanner,andanotherinadifferentmannerandtheirpost-treatmentbehaviordiffers,wecanconcludethatthebehaviordiffersasaconsequenceoftheirdifferenttreatments.Thiscanonlybeconcluded,ofcourse,ifthetwogroupsarecomparabletostartwith.5Randomgroupassignmentallowstherese

6、archerstoassumethattheyhavetwotrulycomparablegroupsattheoutsetoftheexperiment.Afurthersafeguardtoassuregroupcomparability(especiallydesirablewhensubjectpopulationsaresmall)istocomparetheirperformancesonapretest.Iftheexperimentalandcontrolgroupsareequivalentandonlythetreatment

7、theyreceivediffers,thenanypost-treatmenttestdifferencescanbeattributedtothetreatmentitself.66.AnexampleofanexperimentHenrichsen’sfactorialdesignstudyingtheeffectofsandhivariationonthecomprehensibilityofEnglishinput.1.sandhivariation:itreferstophonologicalmodificationsuchascon

8、traction,assimilation.2.thesubjectsoftheexperiment:nativeEnglish-spe