The survey was designed to identify those factors (behaviour, knowledge, attitudes, cultural) that are associated with the HIV epidemic prevention, infection and impact mitigation amongst the population age 10-64 years, and also measure the country’s population-based estimate of HIV/AIDS prevalence amongst the population aged 18 months and over.
• Generate a nationally representative population-based estimate of HIV/AIDS prevalence amongst the population 18 months old to 64 years plus.
• Identify and document those factors (i.e. behaviour, knowledge, attitudes, cultural) that are associated with the HIV epidemic prevention, infection and impact mitigation amongst the population age 10-64 years.
• Establish core benchmarks against which successive progress on the impact of the National Response to HIV/AIDS can be measured.
Kind of Data
Sample survey data [ssd]
The target population focused at two levels.
i. For the biomarker segment of the survey, the population covered aged 18 months and above.
ii. The behavioural segment targeted at the population 10-64 years old.
iii. Usual members of the Household
Only private dwellings were within the scope of the survey. Institutional dwellings (prisons, hospitals, army barracks, hotels, etc), Ngamiland Delta, CKGR and with completely industrial area were not within the scope of the survey.
The non-citizen tourists who were in Botswana on holidays and not working here were also not included in the survey. Foreign tourists may, of course, be here as visitors to a selected household for the survey. In such cases they were treated as visitors, their names were recorded and the relevant questions were asked about them only at household level.
Producers and sponsors
Authoring entity/Primary investigators
Central Statistics Office (CSO)
Ministry of Finance and Development Planning
National AIDS Coordinating Agency (NACA)
For BAIS II the sampling frame was based on the 2001 Population and Housing Census. This comprised the list of all Enumeration Area (EA) together with number of households. In 2001 Census, the EAs were framed of manageable size (in terms of dwellings/households), so the primary sampling units (PSUs) were EAs.
Stratification was undertaken such that all districts and major urban centres become their own strata. With regard to increasing precision, consideration was also given to group EAs according to ecological zones in rural districts and according to income categories in cities/towns. Geographical stratification along ecological zones and income categories was expected to improve the accuracy of survey data because homogeneity of the variables within stratum was relatively high.
A stratified two-stage probability sample design was used for the selection of the sample. The first stage was the selection of EAs as Primary Sampling Units (PSUs) selected with probability proportional to measures of size (PPS), where measures of size (MOS) were the number of households in the EA as defined by the 2001 Population and Housing Census. In all 460 EAs were selected with probability proportional to size. At the second stage of sampling, the households were systematically selected from a fresh list of occupied households prepared at the beginning of the survey's fieldwork (i.e. listing of households for the selected EAs). Overall 8380 households were drawn systematically.
Note: See detailed sampling procedure in BAIS-II final report.
Being a multistage design, it follows naturally that the sample selected at each stage represents (or is assumed to) the respective population. The fundamental assumption was that units selected at each stage were similar to those not selected, in respect of characteristics of interest. In the treatment of unit for the non-response the assumption that the responders were similar to non-responders though should not be always taken for granted.
The weights of the sample are equal to the inverse of the probability of selection. Therefore the sampling probabilities at first stage of selection of EAs including probabilities of selecting the households were used to calculate the weights.
Note: See detailed sampling weights calculation in BAIS-II final report.
Dates of Data Collection (YYYY/MM/DD)
Mode of data collection
Type of Research Instrument
The BAIS II has five major components. These are:
1 The Community schedule.
2 The Household schedule.
3 The individual schedule.
4 Workplace schedule and
5 HIV testing.
The BAIS II instruments (household, individual, workplace, community and biomarker) were pre-tested in areas in and around Gaborone in November 2003. Few changes were incorporated in the Individual questionnaire. The introduction of written consent for Biomarker from the respondent was dropped due to the fact of psychological and social factors on the respondents.
Before data entry was carried out, the questionnaires were edited to check if all the relevant questions have been responded to and coded according to the codes designed for the study. Editing and coding started in March 2004 by 19 Coders and finished in August 2004. Data entry was carried out under the supervision of one programmer/supervisor. Consistency checks on the data set as per the Computer edit Specifications designed by the subject matter specialists were performed.