experimental study

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

2、alscience?Iwillanswerthisquestionfirstbyaconceptualdefinition.22.DefinitionTheexperimentalmethodisascientificmethodthatchangesgraduallyconditionsinplanunderacertaincontrol,andaccordingtoobservationrecordsandresearchdata,determinesthecausalitybetweenconditionsandthephenomenonbymeasuringtheaccomp

3、anyingphenomenaandchanges,thenfindsandsummariestheobjectivelawsofSecondLanguageAcquisition.33.ThebasicpremiseofanexperimentThebasicpremiseofanexperimentisthatallfactorssaveoneareheldconstant.Thesinglefactorisvariedtoseewhateffectithasonthephenomenonunderinvestigation.Asstatedearlier,experiments

4、havetwocriteria:①thereareatleasttwogroupsincludedinthestudy,acontrolgroupandanexperimentalgroup;②thesubjectsarerandomlyassignedtooneofthosegroups.45.Whydowehavetwogroups?Thepurposeofhavingthetwogroupsinthestudyisthatifonegroupistreatedinonemanner,andanotherinadifferentmannerandtheirpost-treatme

5、ntbehaviordiffers,wecanconcludethatthebehaviordiffersasaconsequenceoftheirdifferenttreatments.Thiscanonlybeconcluded,ofcourse,ifthetwogroupsarecomparabletostartwith.5Randomgroupassignmentallowstheresearcherstoassumethattheyhavetwotrulycomparablegroupsattheoutsetoftheexperiment.Afurthersafeguard

6、toassuregroupcomparability(especiallydesirablewhensubjectpopulationsaresmall)istocomparetheirperformancesonapretest.Iftheexperimentalandcontrolgroupsareequivalentandonlythetreatmenttheyreceivediffers,thenanypost-treatmenttestdifferencescanbeattributedtothetreatmentitself.66.Anexampleofanexperim

7、entHenrichsen’sfactorialdesignstudyingtheeffectofsandhivariationonthecomprehensibilityofEnglishinput.1.sandhivariation:itreferstophonologicalmodificationsuchascontraction,assimilation.2.thesubjectsoftheexperiment:nativeEnglish-spe