The Botswana AIDS Impact Survey II (BAIS II) is the second sexual behavioral survey implemented at a national population level by Central Statistics Office (CSO) in collaboration with the multi-sectoral stakeholders in the National HIV /AIDS response.
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
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
Data Collection Mode
Data Collection Notes
Out of 229 trainees, 55 supervisors were selected and trained over a period of three weeks (7-14 January and 19-30 January 2004). The other groups of trainees were one hundred and seventy-four (174) enumerators trained over a period of two weeks (19-30 January 2004). Of these 174 enumerators, 159 were recruited as temporary staff, among which 15 were designated for coding and editing duties.
The field staff comprised of 52 supervisors and 144 enumerators, out of which 27 teams were formed. The teams comprised of 4 enumerators, a supervisor and a district supervisor. Depending on the workload and type of terrain, some of the teams had six enumerators. Each team had at least 3 vehicles with drivers. There were 460 EAs and each team was assigned at least 17 EAs during the course of the survey. Four officers who were responsible for the quality control field visits supported the teams. The survey data collection and Biomarker specimen were carried out between 12th February 2004 and 31st of July 2004.
(i). Households Questionnaire: After listing the total households in the selected EAs, supervisors made the selection of occupied households and handed over the list of selected households to respective enumerators. After the introduction of the survey team to the Chief of the village or area, enumerators approached the selected households and informed the purpose of their visit to the Head of the household. Enumerators were trained to explain the main objective of the survey to the respondents and encouraged him/her for the participation in the most important and needed mission. Once the respondent was convinced for participation, enumerator recorded all the relevant information for those members who spent last night in the household. After administering the questionnaire, for the response of individual questionnaire and Biomarker enumerators identified those listed members in this household who fulfilled the criteria as laid down in the household questionnaire. In some cases it was not possible to administer the household questionnaire at the first visit, then call back technique was applied to the maximum of three visits and the final result was recorded in the result box. One household questionnaire was administered for one selected household.
(ii) Individual Questionnaire: The individual questionnaire was filled for all the members of the households who qualified to be an individual respondent, that is those aged 10 – 64 years and are usual members of the household. This questionnaire dealt with information pertaining to various aspects of HIV/AIDS. In some cases it was not possible to administer the individual questionnaire at the first visit, then here also call back technique was applied to the maximum of three visits and the final result was recorded in the result box.
(iii) Workplace Schedule: The workplace schedules were administered to the maximum of 3 institutions available in the selected EAs. One for the private establishment, second for Parastatal and third for Government.
(iv) Community Schedule: The Community schedule was administered to the maximum of 6 available in the selected EAs.
(v) Biomarker Protocol: From the household questionnaire, all the usual members of the households aged 18 months and above were qualifying for the Biomarker.
The quality control team during their field inspections identified some problems relating to recording and interpretation of questions. They advised the teams accordingly. Since most of the coding and editing exercise was done alongside the data collection, it was easy to contact the teams while they were still out in the field and make proper editing and coding of the items.
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.