datascreening-【英文】spss分析前的数据处理-缺失数据,极端数据,正态检验和非正态处理

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1、Statistics-Spring2008Lab#1-DataScreeningThepurposeofdatascreeningisto:(a)checkifdatahavebeenenteredcorrectly，suchasout-of-rangevalues.(b)checkformissingvalues，anddecidinghowtodealwiththemissingvalues•(c)checkforoutliers,anddecidinghowtodealwithoutliers.(d)checkf

2、ornormality,anddecidinghowtodealwithnon-normality.1.Findingincorrectlyentereddata■Yourfirststepwith“DataScreening”isusing“Frequencies”1.SelectAnalyze—>DescriptiveStatistics—>Frequencies2.Moveallvariablesintothe“Variable(s)”window.3.ClickOK.■Outputbelowisforonlyt

3、hefour“system”variablesinourdatasetbecausecopy/pastingtheoutputforallvariablesinourdatasetwouldtakeuptoomuchspaceinthisdocument.■The“Statistics”boxtellsyouthenumberofmissingvaluesforeachvariable.Wewillusethisinformationlaterwhenwearediscussingmissingvalues.Stati

4、sticssystem1system2system3system4NValid327326325327Missing0120■Eachvariableisthenpresentedasafrequencytable.Forexample，belowweseetheoutputfor“system1”.Bylookingatthecodingmanualforthe“Legalbeliefs”survey，youcanseethattheavailableresponsesfor“system1”are1through1

5、1.Bylookingattheoutputbelow,youcanseethatthereisanumberout-of-range:“13”.(NOTE-inyourdatasettherewillnotbea“13”becauseIgaveyouthescreeneddataset，soIhaveincludedthe“13”intothisexampletoshowyouwhatitlookslikewhenanumberisoutofrange.)Since13isaninvalidnumber，youthe

6、nneedtoidentifywhy“13”wasentered.Forexample，didthepersonenteringdatamakeamistake?Or，didthesubjectrespondwitha“13”eventhoughthequestionindicatedthatonlynumbers1through11arevalid?Youcanidentifythesourceoftheerrorbylookingatthehardcopiesofthedata.Forexample,firstid

7、entifywhichsubjectindicatedthe“13”byclickingonthevariablenametohighlightit(system1)，andthenusingthe“find”functionby:Edit―>Find，andthenscrollingtothelefttoidentifythesubjectnumber.Then，huntdownthehardcopyofthedataforthatsubjectnumber.systemlFrequencyPercentValidP

8、ercentCumulativePercentValid141.21.21.222.6.61.83134.04.05.84206.16.111.95175.25.217.164313.113.130.374413.513.543.787522.922.966.797623.223.289.910257.67.697.61172.1