Behavioural Surveillance Surveys - The Wisdom of Whores

Instructions for using form 4 - the Cluster Information Sheet
It is very important that the interviewing team (with the help of the supervisor if
necessary), completes all the information specified on the cluster information sheet.
This will allow for calculating sampling probabilities and performing a weighted analysis
(should that be necessary).
1. The estimated measure of size is whatever was obtained during the mapping and development
of the sampling frame.
2. The actual measure of size on the day of the survey is needed to help determine how accurate
the PPS sampling was. If very different measures of size are found than what was expected,
this actual measure of size will be essential for calculating the sampling probability, and
ultimately the sampling weight. The measure of size does not need to be exact, but should
approximate as closely as possible the number of target group members at the site.
3. The number of people approached to be interviewed refers to people who are randomly
selected at the site. This number is used as the denominator for the refusal rate for the cluster.
4. The number of people who refuse to be interviewed refers to people who are invited to
participate in the survey (after being randomly selected), but who decline to be interviewed.
It is used as the numerator for the refusal rate for the cluster.
5. The number of duplicates refers to people who have already been interviewed as part of this
survey. This may happen if you are using a “take-all” approach and the site was visited
previously. It may also happen if this is a mobile population and you happen to select a person
who was previously interviewed at another site.
6. The number of interviews completed refers to the number of people who were randomly
selected to be interviewed, and for whom a questionnaire was completed.
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A PPEN DI X 4 B EHAV I OR A L SURV EI L L A NC E S U R V EY S