title: A comparison of procedures to test for moderators in mixed-effects meta-regression models.
abstract: Several alternative methods are available when testing for moderators in mixed-effects meta-regression models. A simulation study was carried out to compare different methods in terms of their Type I error and statistical power rates. We included the standard (Wald-type) test, the method proposed by Knapp and Hartung (2003) in 2 different versions, the Huber-White method, the likelihood ratio test, and the permutation test in the simulation study. These methods were combined with 7 estimators for the amount of residual heterogeneity in the effect sizes. Our results show that the standard method, applied in most meta-analyses up to date, does not control the Type I error rate adequately, sometimes leading to overly conservative, but usually to inflated, Type I error rates. Of the different methods evaluated, only the Knapp and Hartung method and the permutation test provide adequate control of the Type I error rate across all conditions. Due to its computational simplicity, the Knapp and Hartung method is recommended as a suitable option for most meta-analyses.
authors.affiliation: Department of Psychiatry and Neuropsychology, Maastricht University.
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Viechtbauer
authors.affiliation: School of Social and Community Medicine, University of Bristol.
authors.forename: José Antonio
authors.initials: JA
authors.lastname: López-López
authors.affiliation: Department of Basic Psychology and Methodology, University of Murcia.
authors.forename: Julio
authors.initials: J
authors.lastname: Sánchez-Meca
authors.affiliation: Department of Basic Psychology and Methodology, University of Murcia.
authors.forename: Fulgencio
authors.initials: F
authors.lastname: Marín-Martínez
mesh_terms: D003627:Data Interpretation, Statistical; D006801:Humans; D015201:Meta-Analysis as Topic; D012044:Regression Analysis