Post-test effects of positive psychology interventions on depressive symptoms. The square boxes show effect size and sample size (the larger the box, the larger the sample size) in each study, and the line the 95% confidence interval. The diamond reflects the pooled effect size and the width of the 95% confidence interval.
Bolier et al. BMC Public Health 2013 13:119 doi:10.1186/1471-2458-13-119