Meta-analyzing dependent correlations: an SPSS macro and an R script.

The presence of dependent correlation is a common problem in meta-analysis. Cheung and Chan (2004, 2008) have shown that samplewise-adjusted procedures perform better than the more commonly adopted simple within-sample mean procedures. However, samplewise-adjusted procedures have rarely been applied in meta-analytic reviews, probably due to the lack of suitable ready-to-use programs. In this article, we compare the samplewise-adjusted procedures with existing procedures to handle dependent effect sizes, and present the samplewise-adjusted procedures in a way that will make them more accessible to researchers conducting meta-analysis. We also introduce two tools, an SPSS macro and an R script, that researchers can apply to their meta-analyses; these tools are compatible with existing meta-analysis software packages.