Tanzania HIV/AIDS Indicator Survey 2003-2004
Tanzania, 2003 - 2004
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TZA-NBS-HIS-2003-v01
Tanzania HIV/AIDS Indicator Survey 2003-2004
| Name | Country code |
|---|---|
| Tanzania | TZA |
Demographic and Health Survey [hh/dhs]
Tanzania HIV/AIDS Indicator Survey 2003-2004 is the first round of HIV/AIDS Survey.
The main objective of the survey was to provide HIV/AIDS programme managers and policymakers with information needed to guide planning and implementation of interventions, including resource mobilisation and allocation, monitoring and evaluation of existing programmes, and designing new and effective strategies for combating the epidemic
The 2003-04 Tanzania HIV/AIDS Indicator Survey (THIS) is the first population-based, comprehensive survey on HIV/AIDS to be carried out in Tanzania. The survey was initiated by the Tanzania Commission for AIDS (TACAIDS) with the purpose of getting national baseline data on the prevalence of HIV infection. The survey was not meant to replace the sentinel surveillance system undertaken by the Ministry of Health under its National AIDS Control Programme (NACP), but rather to form a basis for monitoring the national HIV/AIDS response.
The survey obtained information on knowledge/awareness, attitudes, and behaviour regarding HIV/AIDS. The overall goal of the survey was to provide programme managers and policymakers involved in HIV/AIDS programmes with information needed to effectively plan and implement future interventions, including resource mobilisation and allocation.
More specifically, the objectives of the 2003-04 THIS were:
• To measure HIV prevalence among women and men aged 15-49;
• To assess levels and trends in knowledge about HIV/AIDS, attitudes towards those infected with the disease, and sexual behavioral practices;
• To collect information on the proportion of adults who are chronically sick, the extent of orphanhood, and care and support levels;
• To gauge the extent to which these indicators vary by characteristics of the individual such as age, sex, region, education, marital status and poverty status.
Sample survey data [ssd]
Household and Individual
Version
Version 01(Public use file for web dissemination)
2005-03
Scope
Household questionnaire:Identification, Interviewer Visits, Household Schedule, Education, Household Characteristics, Support for Vulnerable Households.
Individual questionnaire:Identification, Interviewer Visits, Respodent's Background, Reproduction, Marriage and Sexual Activity, Husband,s Background, HIV/AIDS, Other Reproductive Health Issues, Blood Spot Collection.
| Topic | Vocabulary | URI |
|---|---|---|
| HEALTH [8] | CESSDA | http://www.nesstar.org/rdf/common |
Coverage
Tanzania Mainland
Clusters
Women and Men aged 15-49
Producers and sponsors
| Name | Affiliation |
|---|---|
| National Bureau of Statistics | Ministry of Planning, Empowerment and Economics. |
| Name | Role |
|---|---|
| National Bureau of Statistics | Data producer |
| Tanzania Commission for AIDS | Monitoring and Implementation of THIS |
| The National AIDS Control Programme | Technical Assistance |
| The Prime Minister's Office | Technical Assistance |
| The President's Office of Planning and Privatisation | Technical Assistance |
| Ministry of Health | Technical Assistance |
| Ministry of Labour, Youth Development and Sports | Technical Assistance |
| ORC Macro | Technical Assistance |
| National Reference Laboratory | Testing of Blood |
| Name | Role |
|---|---|
| United States Agency for International Development Agency | Financial Support |
| Embassy of Ireland | Financial Support |
| Name | Affiliation | Role |
|---|---|---|
| Census and Surveys Technical Working Group | Poverty Reduction Strategy Framework | Accepting the Survey |
| The Research and Analysis Technical Working Group | Poverty Reduction Strategy Framework | Accepting the Survey |
| The Nurses | Ministry of Health | Interviewers |
Sampling
The sample for the 2003-04 THIS covered the population residing in households in Tanzania Mainland only. Zanzibar was excluded from the survey because of a recent survey that included HIV/AIDS indicators. A representative probability sample of 6,900 households was selected for the THIS. This sample was constructed to allow separate estimates for some indicators for each of the 21 regions on the mainland, as well as for urban and rural areas separately. As a result of disproportionate sampling, the THIS sample is not self-weighting at the national level and weighting factors have been applied to the data in all tables, unless otherwise specified. The THIS utilised a two-stage sample design. The first stage involved selecting sample points (clusters), consisting of enumeration areas delineated for the 2002 Population and Housing Census. A total of 345 clusters (87 urban and 258 rural) were selected. Sixteen clusters were selected in each region except Dar es Salaam, where 25 clusters were selected. NBS carried out a field operation in which all households living in the selected clusters were listed.
The second stage of selection involved the systematic sampling of households from these lists. A sample of 20 households was drawn from each cluster. All women and men aged 15-49 years who were either usual 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. In addition to the data collected through interviews, respondents were asked to provide few drops of blood for subsequent testing for HIV in the laboratory.
QUESTIONNAIRES
Two types of questionnaires were used in the survey, namely: the Household Questionnaire and the Individual Questionnaire. The contents of these questionnaires were based on model questionnaires developed by the MEASURE Demographic and Health Surveys (DHS) programme. In consultation with TACAIDS, NACP and other government agencies and local organisations, NBS modified the DHS model questionnaires to reflect relevant issues on HIV/AIDS in Tanzania. The questionnaires were then translated from English into Kiswahili and 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 and relationship to the head of the household. 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 non-income proxy indicators about the household's dwelling unit, such as the source of water, type of toilet facilities, materials used for the floor, roof and walls of the house, ownership of various durable goods and land, and household food insecurity. The Household Questionnaire also included questions as to whether household members were seriously ill and whether anyone in the household had died in the past 12 months. In such cases, interviewers asked whether the household had received various kinds of care and support, such as financial assistance, medical support, or social or spiritual support. The Individual Questionnaire was used to collect information from women and men aged 15-49 years and covered the following topics:
• Background characteristics (age, education, media exposure, employment, religion, etc.)
• Reproductive history (number of births and—for women—date of last birth, birth
registration, current pregnancy, and current family planning use)
• Marriage and sexual activity
• Husband’s background
• Knowledge about HIV/AIDS and exposure to specific HIV-related mass media
programmes
• Attitudes towards people living with HIV/AIDS
• Knowledge and experience with HIV testing
• Knowledge and symptoms of other sexually transmitted infections (STIs)
• Circumcision
All aspects of the THIS data collection were pre-tested in September 2003. A small team of field staff were trained for two weeks; the field staff then proceeded to conduct interviews in 180 households. The lessons learned from the pretest were used to finalise the survey instruments and logistical arrangements for the survey.
Table 1.1 shows response rates for the survey. A total of 6,901 households were selected in the sample, of which 6,595 were occupied and therefore eligible for interviews. The shortfall was largely due to structures that were found to be vacant or destroyed. Of the existing households, 6,499 were successfully interviewed, yielding a household response rate of almost 99 percent. In the households interviewed in the survey, 7,154 eligible women were identified; interviews were completed with 6,863 of these women, yielding a response rate of 96 percent. With regard to men, 6,196 eligible men were identified, of which 5,659 were interviewed, yielding a response rate of 91 percent. The response rates are higher in rural than urban areas, although for women, the rates are almost the same.
The principal reason for non-response among both eligible men and women was the failure to find individuals despite repeated visits to the household. The lower response rate for men reflects the more frequent and longer absences of men from the household. Details of the HIV testing response rates are discussed in Chapter 8. The table for response rate illustrated on page six of the report.
Survey instrument
Two types of questionnaires were used in the survey, namely: the Household Questionnaire and the Individual Questionnaire. The contents of these questionnaires were based on model questionnaires developed by the MEASURE Demographic and Health Surveys (DHS) programme. In consultation with TACAIDS, NACP and other government agencies and local organisations, NBS modified the DHS model questionnaires to reflect relevant issues on HIV/AIDS in Tanzania. The questionnaires were then translated from English into Kiswahili and 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 and relationship to the head of the household. 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 non-income proxy indicators about the household's dwelling unit, such as the source of water, type of toilet facilities, materials used for the floor, roof and walls of the house, ownership of various durable goods and land, and household food insecurity. The Household Questionnaire also included questions as to whether household members were seriously ill and whether anyone in the household had died in the past 12 months. In such cases, interviewers asked whether the household had received various kinds of care and support, such as financial assistance, medical support, or social or spiritual support.
The Individual Questionnaire was used to collect information from women and men aged 15-49 years and covered the following topics:
• Background characteristics (age, education, media exposure, employment, religion, etc.)
• Reproductive history (number of births and—for women—date of last birth, birth
registration, current pregnancy, and current family planning use)
• Marriage and sexual activity
• Husband’s background
• Knowledge about HIV/AIDS and exposure to specific HIV-related mass media
programmes
• Attitudes towards people living with HIV/AIDS
• Knowledge and experience with HIV testing
• Knowledge and symptoms of other sexually transmitted infections (STIs)
• Circumcision
All aspects of the THIS data collection were pre-tested in September 2003. A small team of field staff were trained for two weeks; the field staff then proceeded to conduct interviews in 180 households. The lessons learned from the pretest were used to finalise the survey instruments and logistical arrangements for the survey.
Data collection
| Start | End |
|---|---|
| 2003-12-08 | 2004-03-30 |
- Face-to-face [f2f]
| Name | Affiliation |
|---|---|
| National Bureau of Statistics | Ministry of Planning, Empowerment and Economics |
Data collection took place over a four-month period, 8 December 2003 to 30 March 2004. Eleven interviewing teams were involved in the exercise. Each team consisted of one supervisor, four female interviewers, one male interviewer, and one driver. Seven senior staff from NBS coordinated and supervised fieldwork activities. ORC Macro staff participated in the training as well as in field supervision for interviews and blood sample collection, and staff from TACAIDS monitored the overall field work. A quality control team periodically visited teams in the field to check their work and re-interview some households.
Data collection took place over a four-month period, 8 December 2003 to 30 March 2004. Eleven interviewing teams were involved in the exercise. Each team consisted of one supervisor, four female interviewers, one male interviewer, and one driver. Seven senior staff from NBS coordinated and supervised fieldwork activities. ORC Macro staff participated in the training as well as in field supervision for interviews and blood sample collection, and staff from TACAIDS monitored the overall field work. A quality control team periodically visited teams in the field to check their work and re-interview some households.
All women and men who were interviewed were asked to voluntarily provide some drops of blood for HIV testing. The protocol for blood specimen collection and analysis was based on the anonymous linked protocol developed by DHS and approved by ORC Macro’s Institutional Review Board. In Tanzania, the National Institute for Medical Research (NIMR) reviewed the protocol and provided ethical clearance for conducting the survey. The protocol allows for the linking of the HIV test results to the socio-demographic data collected in the Individual Questionnaires, provided that information potentially identifying an individual is destroyed before the linking takes place. This required that identification codes be deleted from the data file and that the back page of the Individual Questionnaire containing the bar code labels be destroyed prior to merging the HIV results with the individual data file.
For the purposes of blood sample collection, all interviewers were nurses recruited with the assistance of the Ministry of Health. To obtain informed consent for blood taking for HIV testing, the interviewer explained the procedures, the confidentiality of the data, and the fact that test results could not be linked or made available to the subject, and provided respondents with information about how they could obtain their HIV status by going to the nearest center that provides voluntary counselling and testing (VCT) services. If respondents consented, the interviewer collected a dried blood spot sample on a filter paper card from a finger prick using a single-use, spring-loaded, sterile lancet. Each blood sample was given a bar code label, with a duplicate label attached to the respondent’s Individual Questionnaire. A third copy of the same bar code label was affixed to a Blood Sample Transmittal Form in order to track the blood samples from the field to the laboratory. Filter papers were dried overnight in a plastic drying box, after which the interviewer packed them in individual zipper-locked bags with desiccant and a humidity indicator card and placed them in a larger zipperlock bag with other blood spots for that sample point. Blood samples were periodically collected in the field along with the completed questionnaires and transported to NBS headquarters in Dar es Salaam for logging in, after which they were taken to the Muhimbili University College of Health Sciences reference laboratory for HIV testing. At the laboratory, the blood spot samples were kept refrigerated until testing was started in mid-March 2004. After the samples and controls were allowed to attain room temperature, a circle was punched from the centre of the blood spot. The blots were placed in micro-titer plates that contained 200 microlitres of elution buffer and were labeled with the bar codes. The samples were left to elute overnight at 4oC. These eluates were then tested with the Vironostika Uniform 2 Ag/Ab test kit, along with one known HIV-negative spot and two known HIV-positive spots. All samples that tested positive and 10 percent of samples that tested negative on the first ELISA (enzyme-linked immunosorbent assay) test were then tested with a second ELISA, the Vironostika Uniform 2 Plus O.
The original protocol called for testing all discrepant samples with a Western Blot test; however, given the expense of the Western Blot, it was decided to first submit all discrepant samples to retesting on both the first and second ELISA tests. All samples that were still discrepant were tested with the INOLIA HIV confirmation Western blot kit (Innogenetics Belgium).
Data processing
The concurrent processing of the data was a distinct advantage for data quality, since NBS was able to periodically run data quality checking tables and to advise field teams of errors detected. The data entry and editing of the questionnaires were completed in June 2004.
Laboratory testing of the blood samples started in mid-March 2004 and continued through September 2004. Results of each test plate were automatically entered into an Excel spreadsheet specially designed by DHS.
Data appraisal
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 2003-04 Tanzania HIV/AIDS Indicator Survey (THIS) to minimise this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2003-04 THIS 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 THIS sample is the result of a multi-stage stratified design, and, consequently, it was necessary to use more complex formulae. The computer software used to calculate sampling errors for the 2003-04 THIS is the ISSA Sampling Error Module. This module used the Taylor linearisation method of variance estimation for survey estimates that are means or proportions. The Jackknife repeated replication method is used for variance estimation of more complex statistics such as fertility and mortality rates. The Taylor linearisation method treats any percentage or average as a ratio estimate, r = y/x,
where y represents the total sample value for variable y, and x represents the total number of cases in
the group or subgroup under consideration. The variance of r is computed using the formula given in page 87 of the report, the detailed explanation of sampling errors found from page 87 to 92 appendix B of the report.
Data Access
| Name | Affiliation | URL | |
|---|---|---|---|
| National Bureau of Statistics | Ministry of Planning, Empowerment and Economics | www.nbs.go.tz | info@nbs.go.tz |
| Is signing of a confidentiality declaration required? | Confidentiality declaration text |
|---|---|
| yes | Confidentiality of respodents is guaranteed by section 20 of Tanzania Statistics act number 1 of 2002 Before being granted access to the dataset, all users have formally agree: 1.all identifying information such as the name and address of respondent has been removed; and 2.the information is disclosed in a manner that is not likely to enable the identification of the particular person or undertaking or business to which it relates. 3.not attempt to identify any particular person or undertaking or business; 4.use of information for research or statistically purpose only; 5.not to disclose the information to any other person, organization 6.when required by the Director General, return all documents made available to him to the Director General; 7.comply with the directions given by the Director General relating to the records. 8.every person involved in the research or statistical project for which information is disclosed pursuant to this section shall make the declaration of secrecy set out in the first schedule. |
Tanzania NBS considered three levels of accessibility:
- Public use files, accessible by all
- Licensed datasets, accessible under certain conditions
- Datasets only accessible on location, for certain datasets
The dataset has been anonymized and available as a public use dataset. It accessible to all for statistical and research purposes only, under the following terms and conditions:
1.The data and other material will not be redistributed or sold to other individuals, institutions, or organization without the written agreement of the National Bureau of Statistics.
2.The data will be used for statistical and scientific research purposes only. They will be used solely for reporting of aggregated information, and not for investigation of specific individuals or organizations.
3.No attempt will be made to produce links among dataset provided by the National Bureau of Statistics, or among data from the (National Bureau of Statistics) and other datasets that could identify individuals or organizations
4.No attempt will be made to re-identify respondents, and no use will be made of the identify of any person or establishment discovered inadvertently. Any such discovery would immediately be reported to the National Bureau of Statistics.
5.Any books, articles, conference papers, theses, dissertations, reports, or other publications that employ data obtained from the National Bureau of Statistics will cite the source of data in accordance with the Citation Requirement provided with each dataset.
"National Bureau of Statistics, Tanzania HIV/AIDS Indicator Survey 2003-2004(THIS 2003-2004), version 1.0 of the public use dataset(March 2005) provided by the National Bureau of Statistics, www.nbs.go.tz"
Disclaimer and copyrights
"The user of the data should acknowledges that, National Bureau of Statistics is the original collector of the data , the authorised distributor of the data, and the relevant funding agency bear no responsibility for use of the data or for interpretations or inferences without a written agreement from the National Bureau of Statistics"
(c) 2003, National Bureau of Statistics
Contacts
| Name | Affiliation | URL | |
|---|---|---|---|
| Director General | National Bureau of Statistics | dg@nbs.go.tz | www.nbs.go.tz |
Metadata production
TZA-NBS-THIS-2003-2004-v01
| Name | Affiliation | Role |
|---|---|---|
| National Bureau of Statistics | Ministry of Planning, Empowerment and Economics | Data producer |
| Accelerated Data Program | PARIS21 | Review of the metadata |
2010-02-09
Metadata version
Version 01.0(January 2010)