|One of the difficulties in choosing indicators of sexual activity among young people is defining an appropriate age group. The most common age group chosen in this context is 15-24. However the relevance of this spectrum may vary considerably from country to country. In many countries with high prevalence HIV epidemics, a sizeable proportion of young people are sexually active before 15. In these cases, surveys focusing on young people should sample respondents below 15. There is also wide variation in the proportions sexually active across the entire age range typically thought to represent "youth". Most indicators of sexual behaviour in young people should therefore be presented separately for the age groups under 15 (where relevant), 15-19, and 20-24. It is possible that the age range sampled in youth surveys will vary by gender within a country. As with all indicators of sexual behaviour, indicators for young people should be presented separately by gender, even when the age range chosen is identical for both sexes.
Past attempts to track sexual behaviour among young people have sometimes been hindered by opposition from parents, teachers or other "gatekeepers" who believe that questions about sexual behaviour are, in the words of the education ministry in one high HIV prevalence country, "not relevant to this cohort". Tracking sexual behaviour among young people is a critical part of good monitoring and evaluation of HIV programmes in countries with generalised epidemics. However programme managers should be aware that these monitoring activities need to be carefully prepared so that their purpose is clearly understood and potential opposition is minimised.
Special attention also needs to be paid to sampling strategies for young people, since those most at risk may well be outside the conventional frameworks that afford access to young people, such as the school system. Sampling strategies then may consider sites where out-of-school youth may gather, such as work sites, night-clubs and soccer fields. Focusing on high transmission sites or locations where sexual activity takes place should also be considered.