Simulation Models for Aggregated Data Meta-Analysis: Evaluation of Pooling Effect Sizes and Publication Biases
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Simulation studies are commonly used to evaluate the performance of newly developed meta-analysis methods. For methodology that is developed for an aggregated data meta-analysis, researchers often resort to simulation of the aggregated data directly, instead of simulating individual participant data from which the aggregated data would be calculated in reality. Clearly, distributional characteristics of the aggregated data statistics may be derived from distributional assumptions of the underlying individual data, but they are often not made explicit in publications. This paper provides the distribution of the aggregated data statistics that were derived from a heteroscedastic mixed effects model for continuous individual data. As a result, we provide a procedure for directly simulating the aggregated data statistics. We also compare our distributional findings with other simulation approaches of aggregated data used in literature by describing their theoretical differences and by conducting a simulation study for three meta-analysis methods: DerSimonian and Laird's pooled estimate and the Trim Fill and PET-PEESE method for adjustment of publication bias. We demonstrate that the choices of simulation model for aggregated data may have a relevant impact on (the conclusions of) the performance of the meta-analysis method. We recommend the use of multiple aggregated data simulation models for investigation of new methodology to determine sensitivity or otherwise make the individual participant data model explicit that would lead to the distributional choices of the aggregated data statistics used in the simulation.
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