The correlation between pre-and post-treatment measures is needed in order to calculate the pre-post effect sizes. This correlation could not be determined from the study reports. Therefore, we followed the recommendation by Rosenthal (1993) and assumed a conservative estimation of r = 0.7. We calculated an average Hedges’ g effect size for studies that included measures of severity of anxiety symptoms and a separate Hedges’ g effect size for measures of depressive symptom severity.
