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TutorialsinQuantitativeMethodsforPsychology
2007,Vol.3(2),p.79.
Apowerprimer
JacobCohen
NewYorkUniversity
Onepossiblereasonforthecontinuedneglectofstatisticalpower
analysisinresearchinthebehavioralsciencesistheinaccessibilityofor
difficultywiththestandardmaterial.Aconvenient,althoughnot
comprehensive,presentationofrequiredsamplesizesisprovided.
Effect‐sizeindexesandconventionalvaluesforthesearegivenfor
operationallydefinedsmall,medium,andlargeeffects.Thesample
sizesnecessaryfor.80powertodetecteffectsattheselevelsaretabled
for8standardstatisticaltests:(1)thedifferencebetweenindependent
means,(2)thesignificanceofaproduct‐momentcorrelation,(3)the
differencebetweenindependentrs,(4)thesigntest,(5)thedifference
betweenindependentproportions,(6)chi‐squaretestsforgoodnessof
fitandcontingencytables,(7)1‐wayanalysisofvariance(ANOVA),
and(8)thesignificanceofamultipleormultiplepartialcorrelation.
FromPsychologicalBulletin(1992),vol112(1),p.155‐159.Copyright©1992bytheAmericanPsychological
Association. Reproducedwithpermission. Forinformationonhowtoobtainthefulltexttothisarticle,
pleasevisithttp://www.apa.org/psycarticles.
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