Table 3.
Between-group effects
| Outcome measures | N comp | Hedges’ g | 95% CI | Z | Heterogeneity | Fail-safe N | |
|---|---|---|---|---|---|---|---|
| Q-value | I 2 | ||||||
| All studies post-treatment (including outliers) | |||||||
| Well-being | 33 | 0.28 | 0.07–0.48 | 2.66** | 146.81*** | 78.20 | 271 |
| Depression | 26 | 0.27 | 0.09–0.45 | 2.97** | 66.40*** | 62.34 | 132 |
| Anxiety | 14 | 0.47 | 0.23–0.71 | 3.78*** | 36.83*** | 64.71 | 135 |
| Stress | 6 | 0.00 | -0.62–0.62 | 0.00 | 25.35*** | 80.28 | 0 |
| All studies post-treatment (excluding outliers)a | |||||||
| Well-being | 29 | 0.24 | 0.13–0.35 | 4.16*** | 35.13 | 20.29 | 137 |
| Depression | 21 | 0.23 | 0.11–0.34 | 3.74*** | 22.26 | 10.16 | 66 |
| Anxiety | 13 | 0.36 | 0.20–0.53 | 4.24*** | 16.96 | 29.26 | 81 |
| Stress | 5 | 0.27 | −0.19–0.73 | 1.16 | 11.02 | 63.69 | 0 |
| Medium or high quality studies post-treatment | |||||||
| Well-being | 14 | 0.19 | 0.02–0.37 | 2.17* | 21.99 | 40.88 | 17 |
| Depression | 12 | 0.07 | -0.19–0.32 | 0.53 | 32.43 | 66.08 | 0 |
| Anxiety | 6 | 0.22 | −0.05–0.49 | 1.57 | 8.39 | 40.39 | 1 |
| Stress | 1 | −0.32 | − 0.85–0.21 | −1.19 | 0.00 | 0.00 | – |
| Studies with 8–12 week follow up (including outliers) | |||||||
| Well-being | 7 | 0.41 | 0.08–0.74 | 2.46* | 19.24** | 68.82 | 28 |
| Depression | 5 | 0.21 | 0.05–0.37 | 2.53* | 2.55 | 0.00 | 4 |
| Anxiety | 4 | 0.35 | 0.12–0.59 | 2.91** | 4.45 | 32.54 | 10 |
| Stress | – | – | – | – | – | – | – |
Note. Ncomp, number of comparisons, CI confidence interval. *p < 0.05. ** p < 0.01. *** p < 0.001. a The effect size for wellbeing (g = 0.24) corresponds with a standardized mean difference Cohen’s d = 0.24 and unweighted mean r = 0.12; the effect size for depression (g = 0.23) corresponds with d = 0.23 and r = 0.11; the effect size for anxiety (g = 0.36) corresponds with d = 0.37 and r = 0.18; the effect size for stress (g = 0.27) corresponds with d = 0.28 and r = 0.14