Heterogeneity
We estimated proportion of heterogeneity relative to sampling error (I2; Higgins and Thompson 2002) and partitioned it into between-study heterogeneity and within-study heterogeneity (Nakagawa & Santos 2012). Current formulations of I2do not accommodate sampling-error covariances for multivariate meta-analytic models. We, therefore, fitted simpler models with only observation-level variances to estimate I2. While this is not ideal, we note that meta-analytic effects of moderators accounting for sampling-error covariances are robust to these simpler models after adjustment with RVE (see Supporting Material).