title: Identification of Real and Artifactual Moderators of Effect Size in Meta-Analysis.
abstract: This article argues that while meta-analytic studies are widely used in psychological literature, heterogeneity and the potential for confounding remain major problems in the interpretation of meta-analytic study results. The article demonstrates the use of exploratory analysis including graphical methods prior to meta-analysis, and introduces a methodology to screen for artifactual effects. These procedures are illustrated on effect size data comparing depression treatment outcome from psychotherapy versus pharmacotherapy. Results support prior findings of a nonsignificant difference in effect size between the two treatments. They also support findings that treatment type accounts for only a very small proportion of outcome variance. However, the results indicate that some previously reported covariates of depression treatment outcome may be artifactual.
authors.affiliation: a Center of Applied Psychology , University of Canberra.
authors.forename: Mark
authors.initials: M
authors.lastname: Collins
authors.affiliation: b Centre for Remote Health , A Joint Centre of Flinders University and Charles Darwin University.|c Central Australian Mental Health Service, NT Department of Health and Families.
authors.forename: Timothy A
authors.initials: TA
authors.lastname: Carey
mesh_terms: D015986:Confounding Factors, Epidemiologic; D003863:Depression / Q000188:drug therapy / Q000628:therapy*; D006801:Humans; D015201:Meta-Analysis as Topic; D011613:Psychotherapy / Q000379:methods; D016896:Treatment Outcome