Statistical analyses procedures
REGRESSIONS
To report baseline characteristics of our sample in accordance with the CONSORT guidelines, we examine baseline differences across the three study arms. Due to the nested nature of our data (i.e., individuals nested in schools), we report adjusted Wald statistics that shows individual-level variations and accounts for potential school-level correlations.To examine the intervention effect on family functioning, we ran separate multilevel mixed-effects models for each of the four measures of the family functioning. All models allow for between-school variability and within-individual variability as a random effect (i.e., random intercepts at individual and school levels, using the <mixed> command in Stata 17). Models estimate subject-specific effects, taking into account the school-level clustering and potential within-individual correlations [To examine how family functioning relate to adolescent mental health over the course of the study, we use the hierarchical variable entry (or hierarchical regressions) method that allows testing influence of multiple predictor variables in a sequential way [To examine whether family functioning moderates the intervention effect on adolescent mental health, we add three-way (group-by-time-by family functioning measure) interaction into the 