Depressive symptoms during the past seven days were measured at each wave with a subset of nine items from the Center for Epidemiological Studies Depression Scale (CES-D). This short form of the CES-D has good reliability and has been used widely in studies of adolescent depression (Dunn et al., 2013). In our overall sample, the Cronbach's α=0.80; internal consistency was invariant across age. The items included “bothered by things that usually don't bother you,” “could not shake off the blues,” “felt that you were just as good as other people [reverse coded],” “had trouble keeping your mind on what you were doing,” “were depressed,” “were too tired to do things,” “enjoyed life [reverse coded],” “were sad,” and “felt that people disliked you.” Each item was rated on a scale of 0-3, representing whether an individual experienced the symptom “never/rarely” to “most/all of the time.”
