Hypothesis_Testing(统计学假设检验)ppt课件.ppt

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1、Chapter9INTRODUCTIONTOHYPOTHESISTESTINGStatisticsforBusiness(ENV)1HypothesisTesting9.1NullandAlternativeHypothesesandErrorsinTesting9.2zTestsaboutaPopulationwithknowns9.3tTestsaboutaPopulationwithunknowns2Hypothesistesting-1Researchersusuallycollectdatafromasamplea

2、ndthenusethesampledatatohelpanswerquestionsaboutthepopulation.Hypothesistestingisaninferentialstatisticalprocessthatuseslimitedinformationfromthesampledataastoreachageneralconclusionaboutthepopulation.3Ahypothesistestisaformalizedprocedurethatfollowsastandardserieso

3、foperations.Inthisway,researchershaveastandardizedmethodforevaluatingtheresultsoftheirresearchstudies.Hypothesistesting-24Thebasicexperimentalsituationforusinghypothesistestingispresentedhere.Itisassumedthattheparameterisknownforthepopulationbeforetreatment.Thepurp

4、oseoftheexperimentistodeterminewhetherornotthetreatmenthasaneffect.Isthepopulationmeanaftertreatmentthesameasordifferentfromthemeanbeforetreatment?Asampleisselectedfromthetreatedpopulationtohelpanswerthisquestion.5Proceduresofhypothesis-testing1.First,westateahypoth

5、esisaboutapopulation.Usuallythehypothesisconcernsthevalueofapopulationparameter.Forexample,wemighthypothesizethatthemeanIQforUICstudentsism=110.2.Next,weobtainarandomsamplefromthepopulation.Forexample,wemightselectarandomsampleofn=100UICstudents.3.Finally,wecomparet

6、hesampledatawiththehypothesis.Ifthedataareconsistentwiththehypothesis,wewillconcludethatthehypothesisisreasonable.Butifthereisabigdiscrepancybetweenthedataandthehypothesis,wewilldecidethatthehypothesisiswrong.6NullandAlternativeHypothesesThenullhypothesis,denotedH0,

7、isastatementofthebasicpropositionbeingtested.Itgenerallyrepresentsthestatusquo(astatementof“noeffect”or“nodifference”,orastatementofequality)andisnotrejectedunlessthereisconvincingsampleevidencethatitisfalse.The(scientificor)alternativehypothesis,denotedHa(orH1),isa

8、nalternative(tothenullhypothesis)statementthatwillbeacceptedonlyifthereisconvincingsampleevidencethatitistrue.Thesetwohypothesesaremutuall