A primer on meta-analysis of correlation coefficients: The relationship between patient-reported therapeutic alliance and adult attachment style as an illustration

The aim of this article is twofold: to offer an introduction to meta-analysis using correlation coefficients to facilitate greater understanding of meta-analytic findings and to guide those interested in conducting meta-analyses. The authors review calculations for a weighted average effect size, the statistical significance of this effect, a test of homogeneity, confidence intervals, and file drawer analysis. They provide a running example of the relationship between patient-reported therapeutic alliance and adult attachment style. Results (k = 12, N = 581.17, weighted average r = .17, p < .0001, 95% confidence interval = .13-.21) indicated a positive, statistically significant relationship, suggesting that greater attachment security is associated with stronger therapeutic alliances, whereas greater attachment insecurity is associated with weaker therapeutic alliances. File drawer results suggested that some caution is warranted in terms of the size of the effect.