“…Swedish participants have thereafter participated in the longitudinal project at age 13, 16, 18/19, and 21 (see e.g., Erling & Hwang, 2004;Frisén, Lunde, & Berg, in press;Frisén & Holmqvist, 2010;Holmqvist, Lunde & Frisén, 2007;Lunde & Frisén, 2011;Lunde, Frisén & Hwang, 2006, 2007. At the follow-up at age 21 (the focus of the present study), participants were contacted by postal mail or e-mail, depending on the contact details they had provided at their previous participation in the longitudinal study.…”