providing evidence-based social skills treatment to preschoolers, adolescents, and young adults with autism spectrum disorder (ASD)

Background characteristics, co-existing psychiatric conditions and dropout rates for the two groups are compared using χ2 tests. Differences between two groups' baseline measures are analyzed using two-sided independent t tests.

The comparison will adopt an intention-to-treat principle. The missing data are substituted with last observation carried forward. To analyze the reasons for the attrition, the dropouts will also be compared to the completers on their clinical variables.

Then, repeated-measures analyses of variance (ANOVAs) are used to calculate between- and within-group effects on all continuous variables. Treatment effect calculations (Cohen's d) will be calculated for each indicator. Differences between the interventions in CGI-I will be examined using a one-way ANOVA. Reported change in the follow-up survey was compared between the PEERS group and the controls using independent t tests.