The Essential Guide to Effect Sizes: Statistical Power, Meta-Analysis, and the Interpretation of Research Results

193 Pages·2010·0.73 MB·English

by  Paul D. Ellis

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The Essential Guide to Effect Sizes
Thissuccinctandjargon-freeintroductiontoeffectsizesgivesstu-
dentsandresearchersthetoolstheyneedtointerpretthepractical
significanceoftheirresearchresults.Usingaclass-testedapproach
that includes numerous examples and step-by-step exercises, it
introducesandexplainsthreeofthemostimportantissuesrelating
totheassessmentofpracticalsignificance:thereportingandinter-
pretation of effect sizes (Part I), the analysis of statistical power
(Part II), and the meta-analytic pooling of effect size estimates
drawn from different studies (Part III). The book concludes with
ahandy listofrecommendations forthoseactively engaged inor
currentlypreparingresearchprojects.
paul d. ellis is a professor in the Department of Management
and Marketing at Hong Kong Polytechnic University, where he
has taught research methods for fifteen years. His research inter-
estsincludetradeandinvestmentissues,marketingandeconomic
development,internationalentrepreneurship,andeconomicgeog-
raphy.ProfessorEllishasbeenrankedasoneoftheworld’smost
prolificscholarsinthefieldofinternationalbusiness.

The Essential Guide to
Effect Sizes
Statistical Power, Meta-Analysis,
and the Interpretation of
Research Results
Paul D. Ellis
cambridgeuniversitypress
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©PaulD.Ellis2010
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Firstpublished2010
PrintedintheUnitedKingdomattheUniversityPress,Cambridge
AcataloguerecordforthispublicationisavailablefromtheBritishLibrary
LibraryofCongressCataloguinginPublicationdata
Ellis,PaulD.,1969–
Theessentialguidetoeffectsizes:statisticalpower,meta-analysis,andthe
interpretationofresearchresults/PaulD.Ellis.
p. cm.
Includesbibliographicalreferencesandindex.
ISBN978-0-521-19423-5(hardback)
1.Research–Statisticalmethods. 2.Sampling(Statistics) I.Title.
Q180.55.S7E45 2010
507.2–dc22 2010007120
ISBN978-0-521-19423-5Hardback
ISBN978-0-521-14246-5Paperback
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ThisbookisdedicatedtoAnthony(Tony)Pecotich

Contents
Listoffigures pageix
Listoftables x
Listofboxes xi
Introduction xiii
PartI Effectsizesandtheinterpretationofresults 1
1. Introductiontoeffectsizes 3
Thedreadedquestion 3
Twofamiliesofeffects 6
Reportingeffectsizeindexes–threelessons 16
Summary 24
2. Interpretingeffects 31
Anage-olddebate–rugbyversussoccer 31
Theproblemofinterpretation 32
Theimportanceofcontext 35
Thecontributiontoknowledge 38
Cohen’scontroversialcriteria 40
Summary 42
PartII Theanalysisofstatisticalpower 45
3. Poweranalysisandthedetectionofeffects 47
Thefoolishastronomer 47
Theanalysisofstatisticalpower 56
Usingpoweranalysistoselectsamplesize 61
Summary 66
vii
viii Contents
4. Thepainfullessonsofpowerresearch 73
Thelowpowerofpublishedresearch 73
Howtobooststatisticalpower 81
Summary 82
PartIII Meta-analysis 87
5. Drawingconclusionsusingmeta-analysis 89
Theproblemofdiscordantresults 89
Reviewingpastresearch–twoapproaches 90
Meta-analysisinsix(relatively)easysteps 97
Meta-analysisasaguideforfurtherresearch 109
Summary 112
6. Minimizingbiasinmeta-analysis 116
Fourwaystoruinaperfectlygoodmeta-analysis 116
1. Excluderelevantresearch 117
2. Includebadresults 122
3. Useinappropriatestatisticalmodels 127
4. Runanalyseswithinsufficientstatisticalpower 130
Summary 131
Lastword:thirtyrecommendationsforresearchers 134
Appendices
1. Minimumsamplesizes 138
2. Alternativemethodsformeta-analysis 141
Bibliography 153
Index 170