ABSTRACT
Procedure Data were gathered from 58 schools in Berlin, Germany. A preliminary screening was conducted to select grade 7-10 adolescents who fulfilled the participatory requirements (i.e., living with both parents and with one opposite-sex adolescent sibling in the same household). Following active parental consent for participation in the study of the selected adolescents, trained researchers administered the standardised questionnaire to the children. Parents and siblings were asked to send their questionnaire in a pre-stamped envelope. For the secondary data collection, families were once again contacted through the participating adolescent at school or-when participants had left the school-via mail. A lottery for minor incentives was held among the participants.
