Trained research staff took height and weight measurements on portable scales and stadiometers. The measurements were then used to calculate body mass index (BMI) as weight (in kilograms) divided by height (in meters) squared. Mental well-being was assessed with the World Health Organization Wellbeing Index, a 5-item scale assessing constructs of positive mood, vitality, and general interests22 that has been previously validated with adolescent populations.23,24 Higher scores indicate greater levels of well-being. Cronbach alpha for the scale in the Youth’12 data was .90. Depressive
symptoms were assessed using the previously validated Reynolds Adolescent Depression scale–Short Form,25 which was validated for use with adolescents in New Zealand.26 The score includes 10 items with 4-point Likert response options. Higher scores indicate greater depressive symptoms. Cronbach alpha for the scale was .90. Family connection was measured with a 9-item standardized scale assessing the following: family having fun together, getting along with family, feeling close to parents, spending enough time with parents, and parents are warm/loving. Higher scores indicate greater family connection. Cronbach alpha for the scale was .84.