Labour Force Survey 2001, February

The sampling procedure for the LFS was a two-stage complex sample. The first stage was the selection with probability proportional to size of PSUs from the 1996 Census list of Enumerator Areas (EAs), to form the Master Sample of 1999. The 1999 Master Sample is thus based on the 1996 Population Census list of EAs and the measure of size used was the number of dwelling units per PSU. The second stage involved the systematic selection of 10 dwelling units from each of the selected PSUs. The Master Sample was stratified into 18 strata, i.e. 9 provinces and within each province by urban / non-urban.

The LFS is a twice-yearly rotating panel household survey. A rotating panel sample involves visiting the same dwelling units on a number of occasions (in this instance, five at most), and replacing a proportion of these dwelling units each round. New dwelling units are added to the sample to replace those that are taken out. The Master Sample is based on the 1996 Population Census of enumeration areas (EA) and the estimated number of dwelling units from the 1996 Population Census. A sample of 30 000 dwelling units was drawn from 3000 primary sampling units (PSUs) (that is 10 dwellingunits per enumerator area (EA)) from the Master Sample. A two-stage sampling procedure was applied and the sample was stratified, clustered and selected to meet the requirements of probability sampling. The Master Sample is based on the 1996 Population Census enumerator areas and the estimated number of dwelling units from the 1996 Population Census. The EAs were grouped within a province by urban/rural, and a disproportional sample of EAs was taken from each group (stratum). Within each explicit stratum the PSUs were stratified by simply arranging them in geographical order by District Council, Magisterial District and, within the magisterial district, by average household income (for formal urban areas and hostels) or EA. The allocated number of EAs was systematically selected with probability proportional to size in each stratum. The sample was explicitly stratified by province and area type (urban/rural).

The careful and scientific selection of the PSUs is the first stage of the sample selection. These identified PSUs must match those areas selected from 1996 census records. After boundary identification, the next stage was to list accurately all the dwelling units in the PSU. A PSU is either one EA from the Census or several EAs when the number of dwelling units in the base or originally selected EA from the census was found to have less than 100 dwelling units. Each EA should have approximately 150 dwelling units but it was found that many contained less than that. Thus, in some cases it has been found necessary to add EAs to the original EA to give our minimum requirement of 100 dwelling units in the first stage of primary sampling units (PSUs). PSUs in the Master Sample consist of 100 to 2445 dwelling units. Special dwellings such as all prisoners in prisons, patients in hospitals, people residing in boarding houses and hotels (whether temporary or semi-permanent), guest houses (whether catering or self-catering), schools and churches are excluded from the sample. The second stage of the sample selection is from the dwelling unit listing. A systematic sample of 10 dwelling units was drawn from each PSU. However, if there was growth of more than 20% in a PSU, then the sample size was increased systematically according to the proportion of growth in the PSU. The same dwellings will be visited on, at most, five different occasions. After this, new dwelling units will be included for interviewing from the same PSU.

The first pilot round of LFS fieldwork took place in February 2000, based on a probability sample of 10 000 dwelling units. The sample was increased to 30 000 dwelling units in September 2000. Both of these surveys were published as discussion documents. The third round took place in February 2001, using the same 30 000 dwelling units.