Table 4.

Within-group effects for four youth outcome domains.

Outcome domain	Point of assessment	Sample		Effect size			Heterogeneity
		K	n	Hedges' g	p-value	95% CI	I2	p-value
Internalizing	Post-intervention	12	438	0.29	<0.001	0.21–0.36	22%	0.229
	Follow-up#	9	397	0.33	<0.001	0.22–0.44	46%	0.065
Externalizing	Post-intervention	14	621	0.26	<0.001	0.18–0.34	37%	0.079
	Follow-up	10	414	0.39	<0.001	0.31–0.47	7%	0.379
Cognitive	Post-intervention	7	231	0.27	0.001	0.11–0.42	52%	0.051
	Follow-up	5	144	0.40	<0.001	0.24–0.55	24%	0.263
Social∧	Post-intervention	5	158	0.28	<0.001	0.14–0.43	25%	0.254

K, number of studies included in the effect size calculation; n, total number of participants in the studies included in the relevant domain;

^#, all follow up assessments are 2 months post-intervention, except for one study included in the Externalizing domain, which conducted follow-up 4 months post-intervention;

^∧, follow-up data were not analyzed for the Social outcomes domain, as only three studies reported follow-up social outcome data.