Sampling Procedure
In January 2004, using Agincourt Health and Population Unit (AHPU) census information, the Agincourt Integrated Family Survey project team drew a stratified random sample of 475 households across all villages in the Agincourt Demographic Surveillance Site, with stratification on both citizenship (South African versus Mozambican) and on whether the household had lost a member to death in the period from June 1, 2002 to May 31, 2003. By "Mozambican household" in the sample design we mean that the nationality of the head of household is Mozambican.
Deviations from the Sample Design
The sample was designed to be 60 percent South African, and 40 percent Mozambican. In execution, slightly fewer South African households without a death were interviewed (187 instead of 190), and one extra South African household with a death was interviewed (96 instead of 95).
These discrepancies were the result of confusion over which households were considered to have a complete interview in cases where the head of household refused to be interviewed. The survey is composed of a household module, to be completed by a knowledgeable household member; an adult module, to be completed by each member aged 18 or older; and a child module, to be completed for each child aged 12 or younger. Some adult household members were migrants who were not in the field site to be interviewed (although the field team made a great effort to make appointments with the household to return at month-end, or at Easter, to interview returning migrants). In addition, some adult members refused to be interviewed. It was decided that if the household module was completed, and at least one adult was interviewed, the household had a complete interview.
In the South African-Death Stratum, an extra household was interviewed because the household head came home for Easter, after the rest of the household had been interviewed, and refused to participate. The field team then interviewed a replacement household, but need not have as a decision had previously been made that if the head refused to participate, but did not stop other members from doing so, then that household's information would be used. However, if a returning head refused to let any members participate (even if they had already been interviewed),that household was not used in the analysis.
Weighting
Sampling weights:
We calculate household inflation factors as the inverse of the product of the probability that an individual household i in strata s was chosen times the number of households surveyed in strata s: (See Angus Deaton, Analysis of Household Surveys, 1997, page 50, for details.)
The inflation factors, calculated using actual sample sizes from Box 1, and the number of households of each type in the field site, are given in Box 2. These inflation factors are also included in the household level data file under the name "Hweight."