Table 1 Characteristics of study population
Number resident in ACDSA on 1 January 2003 aged 12–25 years1008910469
Number who participated in at least one sexual behaviour survey during 2003–7 (% of number resident)6728 (67%)7917 (76%)
Ever had sex
Number whose sexual debut was before the start of the observation period (total, %)*2345 (6374; 37%)2924 (7648; 38%)
Median (IQR) age (years) of those who had already sexually debuted19.7 (18.0–21.8)20.8 (19.1–22.8)
Analysis population: number who had not already sexually debuted by the start of the observation period40294724
  • ACDSA, Africa Centre Demographic Surveillance Area; IQR, interquartile range.

  • *AFS was missing for 48 women (1%) and 95 men (3%); 6 other women and 5 men were excluded because their AFS report was higher than their age at time of interview.