Hester van Eeren

| Chapter 5 5 | 94 is not uncommon within ROM because data is not gathered for specific research purposes (Stichting Benchmark GGZ (SBG), 2016). To reduce uncertainty in the statistical analyses and results, these 697 families formed the study sample for the statistical analyses. Adolescents who had received FFT and completed the primary outcome measure differed significantly from those who did not with regard to their country of birth, living situation, and whether or not they had a court order before treatment (see Table I in Supplemental Material). Adolescents who received MST and completed the assessment after finishing treatment differed from those who did not with regard to their country of birth, living situation, engagement in school or work, whether or not they had a court order before treatment, as well as the country of birth, level of education, and employment status of their primary caregiver, and whether or not this primary caregiver had a partner (see Table II in Supplemental Material). In addition to the study sample of 697 adolescents, the effectiveness of the treatments was compared between the two subsamples of youth with and without a court order. Of the 422 adolescents who received MST, 246 had a court order and 168 did not (for 10 adolescents [2 FFT; 8 MST], the judicial status was unknown). For FFT, 71 adolescents had a court order, while 202 did not. Because the assignment procedure following the RNR model implies that adolescents should be assigned to FFT unless there are indicators that MST would be more suitable (Oudhof et al., 2009), FFT was considered the reference treatment and MST the ‘new’ treatment. Both interventions are continuously monitored on their fidelity and implementation research has shown that both MST and FFT are provided with fidelity in the Netherlands (Manders, Deković, Asscher, van der Laan, & Prins, 2011; van der Rijken, 2015). Instruments Baseline measurements To correct for initial differences between treatment groups, an extensive set of questionnaires were completed at the beginning of treatment. The therapist recorded several demographics of the adolescents and their primary caregiver. Age, gender, country of birth, living situation, level of education, previous treatment, engagement in school or work, previous court orders, police contacts, and the relation with their father, mother, siblings, and peers were reported for each adolescent. Furthermore, the country of birth, level of education, employment status, and presence of a partner were reported for the primary caregiver (Praktikon/MST-NL, 2012). Table 1 shows all demographic characteristics at baseline separately for both treatment groups. Furthermore, parents completed the CBCL (Achenbach & Rescorla, 2001; Dutch version by Verhulst & van der Ende, 2001a) and the youths themselves completed the Youth Self Report (YSR) (Achenbach & Rescorla, 2001; Dutch version by Verhulst & van der Ende, 2001b). A youth’s internalizing problem behavior, externalizing problem behavior, and the total score of the problem behavior were used for analyses. On both questionnaires, items were completed on a 3-point scale (ranging from 0 = never to 2