Maartje Boer

CHAPTER 7 202 Subjective Wellbeing The first indicator of subjective wellbeing was life satisfaction , using the 7-item Student’s Life Satisfaction Scale (Huebner, 1991). Respondents were asked about their thoughts around their own life, for example whether they think that their life is going well (1 strongly disagree to 6 strongly agree ). The second indicator was self-esteem, using 5 items of the Rosenberg Self-esteem Scale (Rosenberg, 1965). Respondents were asked, for example, whether they felt that they have a number of good qualities (1 strongly disagree to 5 strongly agree ). Both scales have been validated among adolescents extensively and adopted in translated form in many adolescent surveys worldwide (Butler & Gasson, 2005; Proctor et al., 2009). For both subjective wellbeing indicators, we computed mean scores of the items. Across all waves, Cronbach’s alpha for life satisfaction and self-esteem ranged from 0.809 to 0.838 and from 0.777 to 0.825, respectively. Self-Control The first indicator of self-control was attention deficit, measured with a 9-item subscale from the Attention Deficit Hyperactivity Disorder (ADHD)- Questionnaire (Scholte & Van der Ploeg, 1999). Respondents were asked, for example, how often they experience difficulties in sustaining prolonged attentionon tasks or activities (1 never to 5 very often ). The second indicatorwas impulsivity , measured with a 6-item subscale from the ADHD-Questionnaire. Respondentswere asked, for example, howoften they find it difficult towait for their turn (1 never to 5 very often ). The ADHD-Questionnaire has been shown to be a reliable and valid measure of ADHD in Dutch adolescents (Scholte & Van der Ploeg, 1999). For both attention deficit and impulsivity, we calculated mean scores using the subscale items. Cronbach’s alpha for attention deficit and impulsivity ranged from 0.860 to 0.882 and 0.786 to 0.834, respectively. Social Competencies We used perceived friendship competence as indicator for social competencies, measured with the 5-item ‘close friendship’-subscale of the Self-Perception Profile for Adolescents (Harter, 2012; Straathof & Treffers, 1989). The subscale has been shown to provide reliable test scores in several