Guidelines for second generation HIV surveillance - World Health ...

Table 2.3. Summary of methods for estimating population size (continued)
Category 2: Methods based on data collected from the general population
Method name and description Advantages Disadvantages
Population survey methods with general
population behaviour questions
Network scale-up methods are based
on the idea that people’s social networks
reflect the general population.
Ask a random sample in the general
population to estimate the number of
people they know, and how many of those
people have the behaviour of interest.
• Surveys are common and familiar.
• Straightforward to analyse and easy to
explain to data users
• Can generate estimates from the
general population rather than hard-toreach
populations
• Individuals are often more likely to
report on the behaviour of others
instead of their own behaviour.
• A single survey can be used to create
a size estimate for multiple hidden
populations.
• Difficult to use when the behaviours are
rare or stigmatized
• Only reaches people residing in
households, schools or other institutions
used to create the sampling frame
• Respondents are unlikely to admit to
high risk or stigmatized behaviours
if interview is not confidential or if
interviewer is not skilled at establishing
trust and rapport.
• Average personal network size is
difficult to estimate.
• Subpopulations may not associate with
members of the general population.
• Respondent may be unaware that
someone in his/her network engages in
behaviour of interest.
• Respondents may be hesitant to
admit to knowing individuals with the
specified behaviour.
Evaluating a National Surveillance System
Source: Adapted from Monitoring and evaluation guidelines for HIV prevention for men who have sex with men. MERG Technical Working Group on Most at Risk Populations.
December 2009 (9).
2.2.3. Step 3: Assess the levels of risk intensity among key populations at increased risk
In geographical units where large numbers of people belonging to a key population at increased risk are
concentrated, assess the level of risk intensity based on:
• how frequently these populations engage in unprotected sex or inject drugs with non-sterile or
contaminated needles/syringes (see Table 2.4)
• how big the networks are of persons who use non-sterile/contaminated needles or have sexual
partnerships.
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