Sample Characteristics
Table 1 shows that at each wave, and for each research arm, more males than females were involved and the percentage of students in JSS 1 tended to be a few points lower than that in JSS 2, which in turn tended to be a bit below JSS 3. In each research arm and wave, students ranged in age from under 11 years to over 17 years, with a
median age of 15 years. Three ethnic groups dominated in this sample: Esan, Bini, and Akoko Edo. In view of the greater population in the Northern Senatorial District, 12 of the 30 research sites were selected from there. Consequently, the percentage of cases from the North was usually greater than that from either the Central or the Southern District. Table 2 gives a sense of the sexual behaviour of the youth in the study. For
males, across waves and research arms, a median 63.3% reported never having engaged in sexual intercourse. For females, the corresponding figure was 75.9%. For the males with sexual experience,the median percentage reporting having used a
condom at least once was 25.4%; for females, it was 24.9%. The median percentage reporting condom use on the last occasion was 22.7% for males and 20.3% for females.