After excluding individuals with invalid telephone numbers, persons with insufficient mastery of the German language, and individuals with serious health problems that precluded participation in the interview, 2,844 of the eligible 4,031 persons were interviewed (71% response rate). In the second wave, after 2 years (T2), 2,031 persons (71% of the baseline sample) were reinterviewed. At the 5-year follow-up (T3), 1,641 persons were reinterviewed (58% of the baseline sample). Table 1 presents the sample characteristics for each wave and their effect on attrition rate. Most participants were not married. At baseline most of the participants were in comprehensive secondary school or at university (37%), in professional training (26%), or employed (20%). At T3 most participants were employed (57%) or still at university or in further education (34%). The attrition rate was higher for those who were employed or in professional training. The attrition rate at T3 was also higher for married participants and for participants who had a higher frequency of smoking, sexual risk behavior, or deviance.
