Table 1

Response rates by age and method of recruitment

18–22 years No (%)23–27 years No (%)28–32 years No (%)Total No (%)
Group 1 Mail and telephone:
    Number26 (100)21 (100)18 (100)65 (100)
    Agreed to participate14 (54)14 (67)7 (39)35 (54)
    Urine provided10 (38)12 (57)7 (39)29 (45)
Group 2 Mail:
    Number16 (100)26 (100)27 (100)69 (100)
    Agreed to participate2 (13)6 (23)8 (30)16 (23)
    Urine provided2 (13)5 (19)7 (26)14 (20)
Total12 (29)17 (36)14 (31)43 (32)