For the six studies that reported ITT data for continuous measures of anxiety or depression symptom severity, we examined effect sizes for MBT from pre- to post-treatment. Three studies reported ITT data for anxiety measures. The effect size for the pooled data was Hedges’ g = 1.06 (95% CI: 0.29-1.84, p = .007). Six studies reported ITT data for depression measures. The effect size for this pooled data was Hedges’ g = 0.55 (95% CI: 0.43-0.67, p < .001). The fail-safe N for measures of anxiety severity was 42 (z-value = 7.55), indicating that 42 studies with an effect size of zero would be necessary to nullify this result. The fail-safe N for measures of depression severity was 123 (z-value = 9.07). Given the small number of studies for these analyses, these results should be interpreted with caution.
