title: Moderator effects differ on alternative effect-size measures.
abstract: This paper discusses largely ignored issues regarding moderation of effect-sizes. We show that, under commonly-occurring conditions, popular alternatives for effect-size measures in ANOVA and multiple regression are not moderated identically across independent samples. Effects may appear to be unmoderated according to one effect-size measure but not according to another, or may even be moderated in opposite directions. We identify the conditions under which differential effect-size moderation can occur, and show that they are commonplace. We then review techniques for detecting and dealing with differential moderation of alternative effect-size measures. Finally, we discuss implications for research practice, reporting, replication, and meta-analysis.
authors.affiliation: Research School of Psychology, The Australian National University, Bldg 39, Canberra, ACT, 2601, Australia. michael.smithson@gmail.com.
authors.forename: Michael
authors.initials: M
authors.lastname: Smithson
authors.affiliation: Research School of Psychology, The Australian National University, Bldg 39, Canberra, ACT, 2601, Australia.
authors.forename: Yiyun
authors.initials: Y
authors.lastname: Shou
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D015999:Multivariate Analysis; D012044:Regression Analysis
keywords: ANOVA; Cohen’s d; Effect size; Moderator; Partial correlation; Regression; Regression coefficient; Replication; Semi-partial correlation