Wolfgang is associate professor of methodology and statistics at Maastricht University in the Netherlands. His research is primarily focused on developing statistical methods and software for meta-analysis and the design and analysis of longitudinal and multilevel studies using appropriate mixed-effects models. He is author of the metafor package for R, which covers a wide variety of standard and advanced meta-analytic methods (e.g., fixed/random/mixed-effects models, meta-regression, multilevel and multivariate meta-analysis, network meta-analysis, phylogenetic and spatio-temporal models).