Department of Epidemiology, Free University Berlin, Haus 562, Fabeckstr. 60-62, 14195 Berlin, Germany. boehning@zedat.fu-berlin.de
Abstract:
In this paper we consider estimating heterogeneity variance with the DerSimonian-Laird (DSL) estimator as typically used in meta-analysis. In its general form the DSL estimator requires inverse population-averaged study-specific variances as weights, in which case the estimator is unbiased. It has become common practice, however, to use estimates of the study-specific variances instead of their population-averaged versions. This can lead to considerable bias. Simulations illustrate these findings.