Multilevel multivariate meta-analysis made easy: An introduction to MLMVmeta

The basic random effects meta-analytic model is overwhelmingly dominant in psychological research. Indeed, it is typically employed even when more complex multilevel multivariate meta-analytic models are warranted. In this paper, we aim to help overcome challenges so that multilevel multivariate meta-analytic models will be more often employed in practice. We do so by introducing MLMVmeta—an easy-to-use web application that implements multilevel multivariate meta-analytic methodology that is both specially tailored to contemporary psychological research and easily estimable, interpretable, and parsimonious—and illustrating it across three case studies. The three case studies demonstrate the more accurate and extensive results that can be obtained via multilevel multivariate meta-analytic models. Further, they sequentially build in complexity featuring increasing numbers of experimental factors and conditions, dependent variables, and levels; this in turn necessitates increasingly complex model specifications that also sequentially build upon one another.