To ensure the survey's representativeness the children and adolescents were selected in a two-step procedure. First, 167 communities were selected to take adequate account of all the federal states (Länder) and community sizes and to ensure a representative portrayal of those communities and the settlement structures in Germany. A screening site is thus weiterlesen
representative of communities with a specific population in a given federal state.
In the second step, a random sampling of children and adolescents was taken from the population registers at residents registration offices.
