Three-level meta-analysis of dependent effect sizes.
Although dependence in effect sizes is ubiquitous, commonly used meta-analytic methods assume independent effect sizes. We describe and illustrate three-level extensions of a mixed effects meta-analytic model that accounts for various sources of dependence within and across studies, because multilevel extensions of meta-analytic models still are not well known. We also present a three-level model for the common case where, within studies, multiple effect sizes are calculated using the same sample. Whereas this approach is relatively simple and does not require imputing values for the unknown sampling covariances, it has hardly been used, and its performance has not been empirically investigated. Therefore, we set up a simulation study, showing that also in this situation, a three-level approach yields valid results: Estimates of the treatment effects and the corresponding standard errors are unbiased.
Faculty of Psychology and Educational Sciences, University of Leuven, Vesaliusstraat 2, 3000, Leuven, Belgium. wim.vandennoortgate@kuleuven-kortrijk.be
Wim
W
Van den Noortgate
José Antonio
JA
López-López
Fulgencio
F
Marín-Martínez
Julio
J
Sánchez-Meca
D015201:Meta-Analysis as Topic; D008960:Models, Psychological; D015233:Models, Statistical; D008962:Models, Theoretical; D015999:Multivariate Analysis; D012494:Sampling Studies