AIDS Indicator Survey 2004-2005, HIV/AIDS Sero-Behavioural Survey (UHSBS)
HIV/AIDS Sero-Behavioural Survey (UHSBS)
The UHSBS is a nationally representative, population-based survey designed to obtain national and sub-national data on the prevalence of HIV and other sexually transmitted infections (STIs) and their social and demographic variations in the country. The survey also obtained information on knowledge, attitudes, and behaviour regarding HIV/AIDS. Data collection took place from 14 August 2004 until late January 2005.
The overall goal of the survey was to provide programme managers and policymakers involved in HIV/AIDS programmes with strategic information needed to monitor and evaluate existing programmes and to effectively design new strategies for combating the epidemic in Uganda. The survey data will also be used to make population projections and to calculate indicators of the UN General Assembly Special Session (UNGASS), USAID, the President’s Emergency Plan for AIDS Relief, UNAIDS, WHO, the Uganda Health Sector Strategic Plan, and the HIV/AIDS National Strategic Framework.
The specific objectives of the 2004-05 UHSBS were the following:
• To obtain accurate estimates of the magnitude and variation in HIV prevalence in Uganda
• To obtain accurate information on behavioural and care indicators related to HIV/AIDS and other sexually transmitted infections
• To obtain accurate information on other HIV/AIDS programme indicators
• To provide information on HIV prevalence to calibrate and improve the sentinel surveillance system
• To determine the magnitude and distribution of syphilis, herpes simplex 2, and hepatitis B infection.
Kind of Data
Sample survey data [ssd]
Unit of Analysis
Women and men 15-49
Producers and sponsors
Authoring entity/Primary investigators
Ministry of Health
Government of Uganda
United States Centers for Disease Control and Prevention
Government of Uganda
United States Agency for International Development
United States Centers for Disease Control and Prevention
United States President's Emergency Plan for AIDS Relief
Japan International Cooperation Agency
The sample for the 2004-05 UHSBS covered the population residing in households in the country. A representative probability sample of 10,425 households was selected for the UHSBS, and an additional 12 households were found during field work for a total of 10,437. The sample was constructed to allow for separate estimates for key indicators for each of nine regions created for the survey, consisting of eight groups of the (then) 56 districts in Uganda, and Kampala, the capital, as a region on its own. The regions were delineated as follows:
1 Central: Kalangala, Kiboga, Luwero, Masaka, Mpigi, Mubende, Nakasongola, Rakai, Sembabule, and Wakiso
3 East Central: Bugiri, Iganga, Jinja, Kamuli, Kayunga, Mayuge, and Mukono
4 Eastern: Busia, Kapchorwa, Mbale, Pallisa, Sironko, and Tororo
5 Northeast: Kaberamaido, Katakwi, Kotido, Kumi, Moroto, Nakapiripirit, and Soroti
6 North Central: Apac, Gulu, Kitgum, Lira, and Pader
7 West Nile: Adjumani, Arua, Moyo, Nebbi, and Yumbe
8 Western: Bundibugyo, Hoima, Kabarole, Kamwenge, Kasese, Kibaale, Kyenjojo, and Masindi
9 Southwest: Bushenyi, Kabale, Kanungu, Kisoro, Mbarara, Ntungamo, and Rukungiri.
The sample was allocated roughly equally across all nine regions to allow a sufficient size in each to produce reliable results. Since the sample was not allocated in proportion to the size of each region, the UHSBS sample is not self-weighting at the national level. Consequently, weighting factors have been applied to the data to produce nationally representative results.
The survey utilised a two-stage sample design. The first stage involved selecting sample points or clusters from a list of enumeration areas (EAs) covered in the 2002 Population Census. A total of 417 clusters composed of 74 urban and 343 rural points were selected. The second stage of selection involved the systematic sampling of households from the census list of households in each cluster. Twenty-five households were selected in each EA.
All women and men aged 15-59 who were either permanent residents of the households in the sample or visitors present in the household on the night before the survey were eligible to be interviewed in the survey. Unlike most studies in which the age category reflects the reproductive age group 15-49, the upper age cutoff in this survey was extended to 59 years so as to include the segment of the population that remains sexually active up to that age. Nevertheless, since most of the internationally accepted HIV/AIDS indicators are based on the population aged 15-49, most of the results presented in this report reflect this age group.
All women and men who were interviewed were asked to voluntarily give a blood sample for testing. Blood samples were also drawn from children under age five years after obtaining consent from their parents or caretakers. Children aged 5-14 years were not enrolled in the survey because other studies have shown a very low HIV prevalence in this age group.
A total of 10,437 households were selected in the sample, of which 9,842 were found to be occupied at the time of the fieldwork. The shortfall is largely a result of structures that were vacant or destroyed. Of existing households, 9,529 were interviewed, yielding a household response rate of 97 percent.
In the households interviewed in the survey, a total of 11,454 eligible women aged 15-59 were identified, of whom 10,826 were interviewed, yielding a response rate of 95 percent. With regard to the male survey results, 9,905 eligible men aged 15-59 were identified, of whom 8,830 were successfully interviewed, yielding a response rate of 89 percent. The response rate for both sexes combined is 92 percent.
Dates of Data Collection (YYYY/MM/DD)
Mode of data collection
Type of Research Instrument
Two questionnaires were used in the survey, a Household Questionnaire and an Individual Questionnaire for women and men aged 15-59. The contents of these questionnaires were based on the model AIDS Indicator Survey questionnaires developed by the MEASURE DHS programme.
In consultation with a spectrum of government agencies and local and international organisations, the MOH and MEASURE DHS adapted the model questionnaires to reflect issues in HIV/AIDS relevant to Uganda. These questionnaires were then translated from English into six local languages—Ateso- Karamajong, Luganda, Lugbara, Luo, Runyankole-Rukiga, and Runyoro-Rutoro. The questionnaires were further refined after the pretest and training of the field staff.
The Household Questionnaire was used to list all the usual members and visitors in the selected households. Some basic information was collected on the characteristics of each person listed, including age, sex, education, relationship to the head of the household, and orphanhood among children under age 18 years. The main purpose of the Household Questionnaire was to identify women and men who were eligible for the individual interview. The Household Questionnaire also collected information on characteristics of the household’s dwelling unit, such as the source of water, type of toilet facilities, materials used for the floor of the house, ownership of various durable goods, and ownership of mosquito nets. Information was also collected on whether the household had received specific types of care and support in the preceding 12 months for any chronically ill adults, any household members who died, and any orphans and vulnerable children. The Household Questionnaire was also used to record respondents’ consent to volunteer to give blood samples. The blood collection and testing procedures are described in the next section.
The Individual Questionnaire was used to collect information from all women and men aged 15-59 and it covered the following topics:
• Background characteristics (e.g., education, media exposure, occupation, religion)
• Marriage and sexual activity
• Husband’s background (for women)
• Knowledge and attitudes towards HIV/AIDS
• Knowledge and prevalence of other sexually transmitted infections (STIs)
All aspects of the UHSBS data collection were pretested in June 2004. For this, five teams were formed, each with 1 supervisor, 2 female interviewers, 2 male interviewers and 2 laboratory technicians. Team members were trained for ten days and then proceeded to conduct the survey in the various districts in which their native language was spoken. In total, 300 individual interviews were completed in the pretest. The lessons learnt from the pretest were used to finalise the survey instruments and logistical arrangements for the survey.
Laboratory testing at the HIV Reference Laboratory (HRL) at the UVRI began shortly after the data collection. Priority was given to the HIV testing, followed by syphilis testing, Hepatitis B testing and herpes simplex. Testing included quality control testing at the CDC laboratory in Entebbe.
The processing of the UHSBS questionnaires began shortly after the fieldwork commenced. Completed questionnaires were returned periodically from the field to the UHSBS project office in Kampala, where they were entered and edited by data processing personnel specially trained for this task. Data were entered using ORC Macro's CSPro computer programme. All data were entered twice (100 percent verification). The concurrent processing of the data was a distinct advantage for data quality, because UHSBS staff were able to advise field teams of errors detected during data entry. The data entry and editing phase of the survey was completed in early March 2005.
Estimates of Sampling Error
The estimates from a sample survey are affected by two types of errors: 1) nonsampling errors, and 2) sampling errors. Nonsampling errors are the results of mistakes made in implementing data collection and data processing, such as failure to locate and interview the correct household, misunderstanding of the questions on the part of either the interviewer or the respondent, and data entry errors. Although numerous efforts were made during the implementation of the 2004-05 Uganda HIV/AIDS Sero-Behavioural Survey (UHSBS) to minimise this type of error, nonsampling errors are impossible to avoid completely and difficult to evaluate statistically.
Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2004-05 UHSBS is only one of many samples that could have been selected from the same population, using the same design and expected size. Each of these samples would yield results that differ somewhat from the results of the actual sample selected. Sampling errors are a measure of the variability between all possible samples. Although the degree of variability is not known exactly, it can be estimated from the survey results.
A sampling error is usually measured in terms of the standard error for a particular statistic (mean, percentage, etc.), which is the square root of the variance. The standard error can be used to calculate confidence intervals within which the true value for the population can reasonably be assumed to fall. For example, for any given statistic calculated from a sample survey, the value of that statistic will fall within a range of plus or minus two times the standard error of that statistic in 95 percent of all possible samples of identical size and design.
If the sample of respondents had been selected as a simple random sample, it would have been possible to use straightforward formulas for calculating sampling errors. However, the 2004-05 UHSBS sample is the result of a multi-stage stratified design, and, consequently, it was necessary to use more complex formulas. The computer software used to calculate sampling errors for the 2004-05 UHSBS is the ISSA Sampling Error Module. This module used the Taylor linearisation method of variance estimation for survey estimates that are means or proportions.
Note: Detail estimates of sampling errors computation is available in Appendix B of the final report.
Uganda Bureau of Statistics, AIDS Indicator Survey 2004 (AIS 2004), version 1.0
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