"Two authors double-screened 1,147 records of potentially relevant studies, finding 38 studies suitable for inclusion in our meta-analysis, covering 100 outcomes and a total sample of n=114,274 individuals. The average effect size (Cohen’s d) of 38 CT studies on our composite outcome of MH and SWB is 0.10 standard deviations (SDs) (95% CI: 0.8, 0.13) for an average time until follow-up of two years. However, there is a substantial amount of heterogeneity in the estimated effects (!!= 64% and 95% Prediction interval: 0.0021, 0.215). CT value, both in absolute terms and relative to previous income, are significant predictors of the effect size. We find only weak evidence that the impact diminishes over time."