= 8), followed by semi-structured interviews in the qualitative phase. The treatment group received a 10-session RTBGI, while the comparison group continued with the routine psychoeducation program implemented in probation settings (SAMBA). Quantitative data were analyzed using the Wilcoxon signed-rank test and the Mann‒Whitney U test, supplemented by Bayesian rank-based analyses. The findings suggest that pretest-posttest changes were observed in the treatment group in the power and fun subdimensions of psychological needs and in the total responsibility score; however, between-group differences in change scores were not clearly supported. A moderate effect size was observed for the between-group difference in the fun subdimension; however, Bayes factors generally indicated weak evidence. Qualitative findings reflected participants' experiences of the intervention process, particularly in relation to the exploration of psychological needs, locus of control, responsibility, and perceived distancing from substance use. Overall, this study provides preliminary and exploratory evidence of patterns of change in psychological need satisfaction, locus of control, and responsibility levels associated with RTBGI.
Özge Gamsız Tunç (Tue,) studied this question.