Statistical Analysis
REGRESSION, RECRUITMENT
 All analyses were conducted using an intent-to-treat framework on 10 multiply imputed data sets, and results were pooled across imputed data sets using Rubin rules.In primary analysis 1, the prevalence of past-year handgun carrying was longitudinally examined over time. In this analysis, we used mixed effects logistic regression models with responses over time clustered within individuals and standard errors clustered within randomized communities using sandwich estimators. A series of binary indicators was included to account for the nesting of the 24 communities in 12 pairs, and a series of binary indicators for grades was included to index the wave of repeated measures. We also estimated grade-specific effects of CTC by interacting the CTC intervention indicator with the grade indicators in these models.In primary analysis 2, cumulative prevalence of handgun carrying from grade 6 through grade 12 was examined. In this analysis, the outcome was whether participants ever (vs never) reported handgun carrying between grades 6 and 12, and the regression models did not include the grade indicators for repeated measures.In CYDS, no information on handgun carrying was collected in grade 5; the earliest information on handgun carrying was collected in grade 6. As such, we conducted several sensitivity analyses to examine the robustness of findings in primary analysis 1 (ie, prevalence of past-year handgun carrying). In sensitivity analysis 1, we shifted the analysis forward by 1 year so grade 6 could be used as the baseline. The rationale for this analysis was twofold. First, as previously mentioned, recruitment continued into grade 6 to increase study participation. Second, even youths recruited in grade 5 had received very little prevention programming by grade 6. In sensitivity analysis 2, we repeated sensitivity analysis 1 only among youths who did not report handgun carrying in grade 6. In sensitivity analysis 3, we adjusted for delinquency in grade 5 as a proxy measure for handgun carrying. Of note, there was baseline equivalence between CTC communities and control communities in delinquency in grade 5.