Statistical-methods-in-RevMan-5

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1、StatisticalalgorithmsinReviewManager5JonathanJDeeksandJulianPTHigginsonbehalfoftheStatisticalMethodsGroupofTheCochraneCollaborationAugust2010DatastructureConsiderameta-analysisofkstudies.Whenthestudieshaveadichotomous(binary)outcometheresultsofeachstudycanbe

2、presentedina2×2table(Table1)givingthenumbersofparticipantwhodoordonotexperiencetheeventineachofthetwogroups(herecalledexperimental(or1)andcontrol(or2)).Table1:BinarydataStudyiEventNoeventTotalExperimentalaibin1iControlcidin2iIftheoutcomeisacontinuousmeasure,

3、thenumberofparticipantsineachofthetwogroups,theirmeanresponseandthestandarddeviationoftheirresponsesarerequiredtoperformmeta-analysis(Table2).Table2:ContinuousdataGroupMeanStandardStudyisizeresponsedeviationExperimentaln1im1isd1iControln2im2isd2iIftheoutcome

4、isanalysedbycomparingobservedwithexpectedvalues(forexampleusingthePetomethodoralog-rankapproachfortime-to-eventdata),then‘O–E’statisticsandtheirvariancesarerequiredtoperformthemeta-analysis.Groupsizesmayalsobeenteredbythereviewauthor,butarenotinvolvedinthean

5、alysis.Table3:OminusEandvarianceVarianceofGroupsizeGroupsizeStudyiOminusE(OminusE)(experimental)(control)ZiVin1in2iForotheroutcomesagenericapproachcanbeused,theuserdirectlyspecifyingthevaluesoftheinterventioneffectestimateanditsstandarderrorforeachstudy(thes

6、tandarderrormaybecalculablefromaconfidenceinterval).‘Ratio’measuresofeffecteffects(e.g.oddsratio,riskratio,hazardratio,ratioofmeans)willnormallybeexpressedonalog-scale,‘difference’measuresof1effect(e.g.riskdifference,differencesinmeans)willnormallybeexpresse

7、dontheirnaturalscale.Groupsizescanoptionallybeenteredbythereviewauthor,butarenotinvolvedintheanalysis.Table4:GenericdataEstimateofStandarderrorofGroupsizeGroupsizeStudyieffectestimate(experimental)(control)θˆSE{θˆi}n1in2iiFormulaeforindividualstudiesIndividu

8、alstudyestimates:dichotomousoutcomesPetooddsratioForstudyidenotethecellcountsasinTable1,withn=a+b,n=c+d,andlet1iii2iiiN=n+n.ForthePetomethod,theindividualoddsratiosaregivenbyi1i2i⎧Z⎫iOR=exp⎨⎬.Pe