Stock计量经济学第9章ppt课件.ppt

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1、Chapter9AssessingStudiesBasedonMultipleRegressionAssessingStudiesBasedonMultipleRegression(SWChapter9)2Isthereasystematicwaytoassessregressionstudies?3AFrameworkforAssessingStatisticalStudies:InternalandExternalValidity(SWSection9.1)4ThreatstoExternalValidityofMultipleRegressionStudies5

2、ThreatstoInternalValidityofMultipleRegressionAnalysis(SWSection9.2)61.Omittedvariablebias7Potentialsolutionstoomittedvariablebias82.Wrongfunctionalform93.Errors-in-variablesbias10Ingeneral,measurementerrorinaregressorresultsin“errors-in-variables”bias.1112“Errors-in-variables”bias,ctd.13

3、Potentialsolutionstoerrors-in-variablesbias144.Sampleselectionbias15Example#1:Mutualfunds16Sampleselectionbiasinducescorrelationbetweenaregressorandtheerrorterm.17Example#2:returnstoeducation18Potentialsolutionstosampleselectionbias195.Simultaneouscausalitybias20Simultaneouscausalitybia

4、sinequations21Potentialsolutionstosimultaneouscausalitybias22InternalandExternalValidityWhentheRegressionisUsedforForecasting(SWSection9.3)23ApplyingExternalandInternalValidity:TestScoresandClassSize(SWSection9.4)24Checkofexternalvalidity25TheMassachusettsdata:summarystatistics26272829Pr

5、edictedeffectsforaclasssizereductionof23031SummaryofFindingsforMassachusetts32Comparisonofestimatedclasssizeeffects:CAvs.MA33Summary:ComparisonofCaliforniaandMassachusettsRegressionAnalyses34Stepback:whataretheremainingthreatstointernalvalidityinthetestscore/classsizeexample?35Omittedvar

6、iablebias,ctd.363738Additionalexampleforclassdiscussion39America’sMostWanted:ThreatstoInternalandExternalValidity40