Impulsivity was measured using 3 items from the Barratt Impulsivity Scale originally developed by Barratt [35 ] and vali dated by Lee et al. [36 ]. For the current sample, Cronbach’s alpha was 0.73.
Self-esteem was measured using five positively worded items from the Rosenberg Self-esteem Scale [37 ]. This scale has shown good reliability [38 ]. In the current sample, Cronbach’s alpha was 0.87.
Childhood maltreatment was measured using eight items originally developed by Pennebaker and Susman [39 (link)]. Items are rated on a 4-point Likert scale. Cronbach’s alpha in the current sample was 0.76.
Deliberate self-harm was measured using three items (cutting, burning, and head banging) included in the Inventory of Statements About Self-injury [40 (link)]. Participants were asked to indicate how many times they had intentionally engaged without lethal intent in each of the behaviours listed during the past 12 months. The scale has shown good internal consistency and construct validity [40 (link),41 (link)].
Deviant behaviour problems included leaving home without notice, truancy at school, violence, peer victimization, bullying (including cyberbullying), and alcohol and substance problems experienced during the past 12 months, and were measured using 15 items developed by the National Youth Policy Institute [42 ]. All items were rated on a 5-point scale (never, 1 time, 2–3 times, 1–2 per week, every day). Cronbach’s alpha for the current sample was 0.79.
Self-esteem was measured using five positively worded items from the Rosenberg Self-esteem Scale [37 ]. This scale has shown good reliability [38 ]. In the current sample, Cronbach’s alpha was 0.87.
Childhood maltreatment was measured using eight items originally developed by Pennebaker and Susman [39 (link)]. Items are rated on a 4-point Likert scale. Cronbach’s alpha in the current sample was 0.76.
Deliberate self-harm was measured using three items (cutting, burning, and head banging) included in the Inventory of Statements About Self-injury [40 (link)]. Participants were asked to indicate how many times they had intentionally engaged without lethal intent in each of the behaviours listed during the past 12 months. The scale has shown good internal consistency and construct validity [40 (link),41 (link)].
Deviant behaviour problems included leaving home without notice, truancy at school, violence, peer victimization, bullying (including cyberbullying), and alcohol and substance problems experienced during the past 12 months, and were measured using 15 items developed by the National Youth Policy Institute [42 ]. All items were rated on a 5-point scale (never, 1 time, 2–3 times, 1–2 per week, every day). Cronbach’s alpha for the current sample was 0.79.
