Behavioural Surveillance Surveys - The Wisdom of Whores

For the purposes of the BSS, the key issue
is whether the different types of sex workers
differ with regard to risk-taking and protective
behaviors. If behaviors are thought or are
known to differ, then the advisable course
of action would be to treat the types of sex
workers as separate domains (i.e., to undertake
separate surveys of each). If not, then they
can be treated as a single domain for sampling
and estimation purposes. Note that in the
initial round of BSS it may not be known
whether the different types of sex workers
differ in terms of key behaviors. Accordingly,
it would be prudent to treat the different groups
as separate domains in at least the first round
in order to obtain some empirical evidence on
this issue. A more informed decision may
then be made as to whether it is necessary to
treat different types of sex workers as separate
domains in subsequent survey rounds.
Irrespective of the distinctions made among
sex workers in different settings, a crucial
distinction for the purposes of sampling is
between sex workers who are associated
with their workplace in a fixed manner,
(e.g., brothels, massage parlors) and those
who have no fixed workplace. This distinction
is important because the application of cluster
sampling methods is relatively straightforward
in the case of sex workers working in fixed
worksites, while depending upon their mode of
operation, sex workers who are not associated
with a particular workplace, but who work at
different sites (sometimes known as freelance
or “floating” sex workers), may pose more
difficult sampling problems. Accordingly, the
two categories are considered separately below.
Sex workers at fixed worksites
In most settings, at least some sex workers
will work from fixed establishments; for
example, brothels, massage parlors, karaoke
lounges, etc. For such workers, a fairly
straightforward application of two-stage cluster
sampling is the recommended approach.
Sampling frame development
As will be the case with most sub-population
surveys, the most difficult aspect of the sampling
operation is likely to be the development of
a sampling frame. Here, key informants and
sub-population members themselves will need
to be consulted as a starting point in the
development of a sampling frame.
As part of the sampling frame development
for establishment-based sex workers, it is
useful to list all the establishments (sites)
where they can be located, and to gather
information on the number of sex workers
associated with the site. This information is
useful for 1) selecting sample PSU’s or clusters
with probability-proportional-to-size (PPS)
should this option be chosen, 2) determining
the appropriate number of sex workers to be
sampled from each cluster, and 3) determining
how many sample sites must be chosen
in order to satisfy the survey’s sample size
requirements.
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A PPEN DI X 3 B EHAV I OR A L SURV EI L L A NC E S U R V EY S