Maartje Boer

CHAPTER 7 214 Class 3: Persistently Low Problematic SMU, Persistently Low SMU Frequency Relative to Class 4, boys were more likely to be in Class 3 than girls ( B = -1.147 p < 0.001, OR = 0.318). Also, adolescents attending pre-university education had a higher probability of being in Class 3 than adolescents attending intermediate or pre-vocational education ( B = -0.633, p = 0.028, OR = 0.532; B = -0.633, p = 0.031, OR = 0.531). Higher self-esteem ( B = 0.881, p = 0.003, OR = 2.423), lower impulsivity ( B = -2.060, p < 0.001, OR = 0.130), and poorer social competencies ( B = -1.606, p < 0.001, OR = 0.202) were associated with a greater probability of being in Class 3. Additional Class Comparisons We also explored other class differences by repeating the multivariate multinomial analysis with other reference categories (see Appendix, Table A7.5). This analysis was not preregistered and therefore considered as additional exploratory analysis. Comparing the classes with the highest level of problematic SMU (Classes 1 and 2), results showed that levels of impulsivity and social competence were higher in Class 1 than in Class 2 ( B = 1.833, p < 0.001, OR = 6.327; B = 2.424, p < 0.001, OR = 11.536). In addition, adolescents in Class 1 showed lower life satisfaction ( B = -0.881, p = 0.020, OR = 0.423), higher attention deficit and impulsivity ( B = 1.048, p = 0.017, OR = 2.928; B = 3.667, p < 0.001, OR = 41.106), and stronger social competencies ( B = 1.369, p = 0.005, OR = 4.182), than adolescents in Class 3. Adolescents in Class 2 showed higher impulsivity and weaker social competencies than adolescents in Class 3 ( B = 1.834, p < 0.001, OR = 6.392; B = -1.028, p = 0.014, OR = 0.365). Discussion The present study investigated adolescents’ trajectories of problematic SMU in parallel with their trajectories of SMU frequency in early and middle adolescence. Four subgroups were identified: two subgroups that showed relatively high levels of problematic SMU over time, of which one reported high and one reported average levels of SMU frequency, and two subgroups that showed low levels of problematic SMU over time, of which one reported low and one reported high levels of SMU frequency. In the subgroup with relatively high levels of problematic SMU and SMU frequency, problematic