indicated by one or two criteria met, bias was deemed “possible,” and if no evidence of bias was found, it was deemed “unlikely.”3. Results3.1. Descriptive characteristicsFor the 18 studies included in the overall meta-analysis, data were collected from 735 participants (see Appendix B). Sample sizes ranged from 11 to 97 participants, M (SD)= 40.83 (25.56). The age of participants ranged from 5.30 to 20.42 years, M (SD)= 10.54 (4.18). 33.3% of studies had study samples with >90% male, and all other samples were between 50% and 90% male. The mean overall standardized cognitive ability of participants was 102.27, ranging from 87.55 to 112.45 across studies. The mean standardized verbal ability of participants was 100.01, ranging from 86.3 to 106.26 across studies. 44.4% of studies reported data on comorbidity of participants, and 50% of studies included participants taking medications. Intervention length ranged from 5 to 97 sessions. 22.2% of the studies included peer tutors.3.2. Overall analysisThe effect sizes (g) ranged in magnitude from g= 0.20 to g= 1.19, with positive effects indicating increases in ratings of social competence (see Table 1). Fig. 2 shows individual effect sizes for this analysis.Participants who received treatment made significantly greater improvements on measures of social competence compared to those in the control group (g= 0.51, K = 18, 95% [CI 0.30, 0.72], Z = 4.75, p< 0.001). This is a medium effect. While the number of studies included in the overall analysis was sufficient, the I2(0.00) was not large enough to justify proceeding with moderator analyses.3.2.1. Publication bias analysis—Evidence of publication bias was found via Egger’s regression test (b= 0.93, p< 0.01), implying asymmetry of studies was detected in the Gates et al.Page 11Clin Psychol Rev. Author manuscript; available in PMC 2018 March 01.Author ManuscriptAuthor ManuscriptAuthor ManuscriptAuthor Manuscript
funnel plot (See Appendix C). Publication bias was not evident according to the trim and fill analysis, where six studies were removed to the left of the mean, making the adjusted effect of GSSI intervention smaller (g= 0.39, 95% [CI 0.20, 0.58]), though still significantly different from zero. In contrast, no evidence of publication bias was found according to the Fail Safe N(98 studies). The combined tandem criteria suggest publication bias is possible.3.3. Informant analysisIn order to investigate the effect of informant on ratings of social competence, five separate meta-analyses were conducted which included measures reported exclusively by parent, teacher, self, observer, or completed as a task. Moderator analyses were conducted when appropriate.3.3.1. Parent-report—Sixteen studies included parent-report measures. The effect sizes for parent-report measures ranged from g= 0.06 to g= 1.03. Fig. 3 displays the individual effect sizes for the parent-report analysis. According to parent-report, participants who received treatment had significantly greater improvements in social competence relative to controls (g= 0.47, K = 16, 95% CI [0.24, 0.70], Z= 4.01, p< 0.01). This is a small effect.