Tanzania HIV/AIDS and Malaria Indicator Survey 2011-2012

Tanzania, 2011 - 2012

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Reference ID

TZA-NBS-HMIS-2011-v01

Producer(s)

National Bureau of Statistics (NBS), Office of the Chief Government Statistician(OCGS-Zanzibar)

Metadata

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Created on

Feb 13, 2022

Last modified

Jul 24, 2024

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Identification

Survey ID number

TZA-NBS-HMIS-2011-v01

Title

Tanzania HIV/AIDS and Malaria Indicator Survey 2011-2012

Country

Name	Country code
Tanzania	TZA

Study type

Demographic and Health Survey [hh/dhs]

Series Information

The 2011-2012 Tanzania HIV/AIDS and Malaria Indicator Survey is the third comprehensive survey on HIV/AIDS carried out in Tanzania. The previous one were the 2003/2004 Tanzania HIV/AIDS Indicator Survey and the 2007/2008 Tanzania HIV/AIDS and Malaria Indicator Survey.

Abstract

The objectives of the 2011-12 THMIS were to collect data on knowledge and behaviour regarding HIV/AIDS and malaria, measure HIV prevalence among women and men age 15-49, and measure the presence of malaria parasites and anaemia among children age 6-59 months. The 2011-12 THMIS follows up on the 2007-08 THMIS and the 2003-04 Tanzania HIV/AIDS Indicator Survey (THIS). The 2011-12 THMIS also updates estimates of selected basic demographic and health indicators covered in previous surveys, including the 1991-92 Tanzania Demographic and Health Survey (TDHS), the 1996 TDHS, the 1999 Reproductive and Child Health Survey, the 2004-05 TDHS, and the 2010 TDHS.

This report contains information collected from the interviewed households. The tables and text contained in this report cover many of the most important indicators and should be used by policy makers and programme administrators to evaluate their activities and plan future directions. Advantage should be taken of the availability of this valuable information to inform the process of policy formulation, planning, monitoring, and evaluation of the HIV/AIDS and malaria programmes in Tanzania. The report will also be useful to all HIV/AIDS and malaria stakeholders, be those at the policy level, programme level, or in academia and research institutions.

Kind of Data

Sample survey data [ssd]

Unit of Analysis

Household and Individual

Version

Version Description

Version 01 (Public use file for web dissemination)

Version Date

2013-03

Scope

Notes

The scope of the Tanzania HIV/AIDS and Malaria Indicator Survey 2011-2012 includes:Household Questionnaire and Individual Questionnaire. These questionnaires are based on the MEASURE DHS standard AIDS Indicator Survey and Malaria Indicator Survey questionnaires and were adapted to reflect the population and health issues relevant to Tanzania.

The Household Questionnaire was used to list all the usual members and visitors of selected households includes;the basic demographic information like age, sex, education, relationship to the head of the household, Survival status of the parents for children under age 18. Also 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 and use of mosquito nets and haemoglobin and malaria testing
results for children age 6-59 months.

The Individual Questionnaire was used to collect information from all eligible women and men age 15-49. Likely topics were Background characteristics (education, media exposure, etc.), Marriage and sexual activity, Employment, Awareness and behaviour regarding HIV/AIDS and other sexually transmitted infections (STIs), Knowledge and awareness of malaria and Other health issues.

Female respondents were asked to provide their birth history for the six years preceding the interview and information about recent fever and treatment of fever for children born since January 2006.

Topics

Topic	Vocabulary	URI
HEALTH [8]	CESSDA

Keywords

HEALTH [8]

Coverage

Geographic Coverage

National Coverage. (The survey covers both the Tanzania Mainland and Zanzibar.)

Geographic Unit

Clusters

Universe

583 clusters.
Approximately 18 households were selected from each sample point for a total sample size of 10,496 households.
All women and men age 15-49 who were either permanent residents of the selected households or visitors who stayed in the household the night before the survey were eligible to be interviewed.
Children age 6-59 months were tested for anaemia and malaria in each household.

Producers and sponsors

Primary investigators

Name	Affiliation
National Bureau of Statistics (NBS)	Ministry Of Finance
Office of the Chief Government Statistician(OCGS-Zanzibar)

Producers

Name	Role
The Tanzania Commission for AIDS	Authorised the survey
Zanzibar AIDS Commission	Authorised the survey
United States Agency for International Development	Technical assistance
Ministry of Finance and Economic Affairs	Resources Mobilization, Monitoring and Emplementation
Tanzania Statistical Master Plan	Resources Mobilization
ICF International	Technical assistance

Funding Agency/Sponsor

Name	Role
United States Agency for International Development	Financial Support
The Tanzania Commission for AIDS	Financial Support
Ministry of Health and Social Welfare	Financial Support
ICF International	Financial Support
TANZANIANS AND AMERICANS IN PARTNERSHIP TO FIGHT HIV/AIDS	Financial Support

Other Identifications/Acknowledgments

Name	Role
The Prime Minister’s Office	Provided Staff
The Ministry of Health and Social Welfare (MoHSW)	Provided Staff
The National AIDS Control Programme (NACP)	Provided Staff
The National Malaria Control Programme (NMCP)	Provided Staff
The Zanzibar Malaria Control Programme (ZMCP)	Provided Staff

Sampling

Sampling Procedure

The sampling frame used for the 2011-12 THMIS was developed by the National Bureau of Statistics (NBS) after the 2002 Population and Housing Census (PHC) and is the same as that used for the 2010 and 2004-05 Tanzania Demographic and Health Surveys (TDHS), the 2007-2008 THMIS, and the 2003-04 Tanzania HIV and AIDS Indicator Survey (THIS). The sampling frame excluded nomadic and institutional populations such as persons in hotels, barracks, and prisons.

The sample was selected in two stages.

The first stage involved selecting sample points (clusters) consisting of enumeration areas (EAs) delineated for the 2002 PHC. A total of 583 clusters were selected. On the Mainland, 30 sample points were selected in Dar es Salaam and 20 were selected in each of the other 24 regions.2 In Zanzibar, 15 sample points were selected in each of the five regions.

The second stage of selection involved the systemic sampling of households. A household listing operation was undertaken in all the selected areas prior to the fieldwork. From these lists, households to be included in the survey were selected. Approximately 18 households were selected from each sample point for a total sample size of 10,496 households.

Because of the approximately equal sample sizes in each region, the sample is not self-weighting at the national level, and weighting factors have been added to the data file so that the results will be proportional at the national level.

Deviations from the Sample Design

The recent formation of the new regions on Mainland Tanzania shifted certain regional boundaries; hence, some regions are no longer comparable with those from previous TDHS and THMIS surveys, and attempts to compare any indicators in affected regions should be performed with caution. Of the former 21 Mainland regions, the boundaries of five (Kagera, Mwanza, Shinyanga, Rukwa, and Iringa) were altered. The boundaries of the remaining 16 are unchanged.

To estimate geographic differentials for certain demographic indicators, the regions of Mainland Tanzania were collapsed into eight geographic zones. Although these are not official administrative zones, this classification is used by the Reproductive and Child Health Section of the MoHSW. Zones were used in each geographic area in order to have a relatively large number of cases and a reduced sampling error.

Response Rate

A total of 10,496 households were selected for the sample, from both Mainland Tanzania and Zanzibar. Of these, 10,226 were found to be occupied at the time of the survey. A total of 10,040 households were successfully interviewed, yielding a response rate of 98 percent. In the interviewed households, 11,423 women were identified as eligible for the individual interview. Completed interviews were obtained for 10,967 women, yielding a response rate of 96 percent. Of the 9,388 eligible men identified, 8,352 were successfully interviewed (89 percent response rate).

The principal reason for nonresponse among both eligible women and men was the failure to find them at home despite repeated visits to the households. The lower response rate among men than among women was due to the more frequent and longer absences of men from the households.

Weighting

Weighting factors have been added to the data file so that the results will be proportional at the national level.

Survey instrument

Questionnaires

Two questionnaires were used for the 2011-12 THMIS: the Household Questionnaire and the Individual Questionnaire.After the preparation of the definitive questionnaires in English, the questionnaires were translated into Kiswahili.

The Household Questionnaire was used to list all the usual members and visitors of selected households. Some basic demographic information was collected on the characteristics of each person, including his or her age, sex, education, and relationship to the head of the household. For children under age 18, survival status of the parents was determined. The data on age and sex of household members obtained in the Household Questionnaire was used to identify women and men who were eligible for the individual interview and HIV testing. 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 and use of mosquito nets. The Household Questionnaire was also used to record haemoglobin and malaria testing results for children age 6-59 months.

The Individual Questionnaire was used to collect information from all eligible women and men age 15-49. These respondents were asked questions on the following topics:
• Background characteristics (education, media exposure, etc.)
• Marriage and sexual activity
• Employment
• Awareness and behaviour regarding HIV/AIDS and other sexually transmitted infections
(STIs)
• Knowledge and awareness of malaria
• Other health issues
Female respondents were asked to provide their birth history for the six years preceding the interview and information about recent fever and treatment of fever for children born since January 2006.

Data collection

Dates of Data Collection

Start	End	Cycle
2011-12-16	2012-04-10	Tanzania Mainland
2012-05-24		Tanzania Mainland

Data Collection Mode

Face-to-face [f2f]

Data Collectors

Name	Affiliation
National Bureau of Statistics	Ministry of Finance

Supervision

Data collection was carried out by 16 field teams, each consisting of one team leader, three female interviewers, two male interviewers, and one driver.

The role of the supervisor was to coordinate field data collection activities including field editing of each questionnaire and ensured that data quality control procedures were maintained.

Five senior staff members from NBS coordinated and supervised the fieldwork activities.

Data Collection Notes

Data collection was carried out by 16 field teams, each consisting of one team leader, three female interviewers, two male interviewers, and one driver. Five senior staff members from NBS coordinated and supervised the fieldwork activities. Data collection in the Mainland took place over a five-month period from 16 December 2011 to 24 May 2012. Data collection in Zanzibar took place from 16 December 2011 to 10 April 2012.

Data processing

Data Editing

Data editing took place at a number of stages throughout the processing, including:
(a) Office editing
(b) Coding of open-ended questions
(c) Editing computer-identified errors.

Editing was done by two data editors. One data editor had the additional responsibility of receiving the blood samples
from the field and checking them before sending them to the appropriate laboratory.

Data appraisal

Estimates of Sampling Error

The estimates from a sample survey are affected by two types of errors: non-sampling errors and sampling errors. Non-sampling 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 2011-12 Tanzania HIV/AIDS and Malaria Indicator Survey (2011-12 THMIS) to minimize this type of error, non-sampling 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 2011-12 THMIS 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 among all possible samples. Although the degree of variability is not known exactly, it can be estimated from the survey results.

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 2011-12 THMIS sample is the result of a multi-stage stratifie d design, and, consequently, it was necessary to use more complex formulas. Sampling errors are computed by SAS, using programs developed by ICF International. These programs use the Taylor linearization method of variance estimation for survey estimates that are means, proportions, or ratios. The Jackknife repeated replication method is used for variance estimation of more complex statistics such as fertility and mortality rates.

Detailed documentation of the estimates of Sampling Error can be found in Appendix B of the "THMIS 2011-2012 Main Report" document provided as an external resource

Access policy

Confidentiality

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.

Access conditions

Tanzania NBS considered three levels of accessibility:

1) Public use files, accessible by all
2) Licensed datasets, accessible under certain conditions
3) 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 Tanzania 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.

Citation requirements

"National Bureau of Statistics, Tanzania HIV/AIDS and Malaria Indicator Survey 2007-2008 (THMIS 2007-2008), version 1.0 of the public use dataset (November 2008) pvovided by the National Bureau of Statistics, www.nbs.go.tz"

Access authority

Name	Affiliation	URL	Email
National Bureau of Statistics (NBS)	Ministry of Finance		dg@nbs.go.tz

Disclaimer and copyrights

Disclaimer

"The user of the data should acknowledges that, Tanzania 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"

Contacts

Name	Affiliation	Email	URL
Director General	National Bureau of Statistics, Tanzania	dg@nbs.go.tz

Metadata production

DDI Document ID

TZA-NBS-THMIS-2011-2012v01

Producers

Name	Affiliation	Role
National Bureau of Statistics	Ministry of Finance	Documentation of the study
Accelerated Data Program	PARIS21	Review of the metadata

Date of Metadata Production

2013-04-15

Metadata version

DDI Document version

Version 1.0

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