The AIDS Indicator Survey (AIS) was developed to provide countries with a standardized tool to obtain indicators for effective monitoring of national HIV/AIDS programs.
The design for the AIS was guided by the need to have a survey protocol that will provide, in a timely fashion and at a reasonable cost, the information required for meeting HIV/AIDS program reporting requirements, including the collection of the President's Emergency Plan For AIDS Relief (PEPFAR), UN General Assembly Special Session on HIV/AIDS (UNGASS), and other indicators while ensuring comparability of findings across countries and over time.
AIS Survey Related Topics
Information on AIS Indicators are available for the following topics:
HIV - Overview of MEASURE DHS research on HIV Prevalence, Indicators, and Services
HIV/AIDS Knowledge, Attitudes, and Behavior - Knowledge of HIV prevention, misconceptions, stigma, higher-risk sexual behavior
HIV Prevalence - Prevalence of HIV by demographic and behavioral characteristics
The 2005 Vietnam Population and AIDS Indicator Survey (VPAIS) was designed with the objective of obtaining national and sub-national information about program indicators of knowledge, attitudes and sexual behavior related to HIV/AIDS. Data collection took place from 17 September 2005 until mid-December 2005.
The VPAIS was implemented by the General Statistical Office (GSO) in collaboration with the National Institute of Hygiene and Epidemiology (NIHE). ORC Macro provided financial and technical assistance for the survey through the USAID-funded MEASURE DHS program. Financial support was provided by the Government of Vietnam, the United States President’s Emergency Plan for AIDS Relief, the United States Agency for International Development (USAID), and the United States Centers for Disease Control and Prevention/Global AIDS Program (CDC/GAP).
The survey obtained information on sexual behavior, and knowledge, attitudes, and behavior regarding HIV/AIDS. In addition, in Hai Phong province, the survey also collected blood samples from survey respondents in order to estimate the prevalence of HIV. The overall goal of the survey was to provide program managers and policymakers involved in HIV/AIDS programs with strategic information needed to effectively plan, implement and evaluate future interventions.
The information is also intended to assist policymakers and program implementers to monitor and evaluate existing programs and to design new strategies for combating the HIV/AIDS epidemic in Vietnam. The survey data will also be used to calculate indicators developed by the United Nations General Assembly Special Session on HIV/AIDS (UNGASS), UNAIDS, WHO, USAID, the United States President’s Emergency Plan for AIDS Relief, and the HIV/AIDS National Response.
The specific objectives of the 2005 VPAIS were:
• to obtain information on sexual behavior.
• to obtain accurate information on behavioral indicators related to HIV/AIDS and other sexually transmitted infections.
• to obtain accurate information on HIV/AIDS program indicators.
• to obtain accurate estimates of the magnitude and variation in HIV prevalence in Hai Phong Province.
Kind of Data
Sample survey data [ssd]
Unit of Analysis
- Women age 15-49
- Men age 15-49
Topics covered in the study:
• Alcohol Consumption
• Birth Registration
• HIV Behavior
• HIV Knowledge
• HIV Testing
• Malaria Module ‹Includes bednet inventory
• Men's Survey
• Women's Status
The survey questionnaires covered the following topics:
• Household schedule
• Household characteristics
Womena and Men Questionnaire
• Background characteristics (education, media exposure, occupation, religion, employment, etc.)
• Reproduction (number of births, date of last birth, current pregnancy)
• Marriage and sexual activity
• Knowledge and attitudes towards HIV/AIDS
• Knowledge and reported prevalence of other Sexually Transmitted Infections (STIs), and other health issues (injections).
• Blood collection (in Hai Phong)
Producers and sponsors
General Statistical Office (GSO)
Government of Vietnam
National Institute for Hygiene and Epidemiology (NIHE), Ministry of Health
Government of Vietnam
Government of Vietnam
United States Agency for International Development
United States Centers for Disease Control and Prevention
Global AIDS Program
The sampling frame for the 2005 Vietnam Population and AIDS Indicator Survey (VPAIS) was the master sample used by the General Statistical Office (GSO) for its annual Population Change Survey (PCS 2005). The master sample itself was constructed in 2004 from the 1999 Population and Housing Census. As was true for the VNDHS 1997 and the VNDHS 2002 the VPAIS 2005 is a nationally representative sample of the entire population of Vietnam.
The survey utilized a two-stage sample design. In the first stage, 251 clusters were selected from the master sample. In the second stage, a fixed number of households were systematically selected within each cluster, 22 households in urban areas and 28 in rural areas.
The total sample of 251 clusters is comprised of 97 urban and 154 rural clusters. HIV/AIDS programs have focused efforts in the four provinces of Hai Phong, Ha Noi, Quang Ninh and Ho Chi Minh City; therefore, it was determined that the sample should be selected to allow for representative estimates of these four provinces in addition to the national estimates. The selected clusters were allocated as follows: 35 clusters in Hai Phong province where blood samples were collected to estimate HIV prevalence; 22 clusters in each of the other three targeted provinces of Ha Noi, Quang Ninh and Ho Chi Minh City; and the remaining 150 clusters from the other 60 provinces throughout the country.
Prior to the VPAIS fieldwork, GSO conducted a listing operation in each of the selected clusters. All households residing in the sample points were systematically listed by teams of enumerators, using listing forms specially designed for this activity, and also drew sketch maps of each cluster. A total of 6,446 households were selected. The VPAIS collected data representative of:
• the entire country, at the national level
• for urban and rural areas
• for three regions (North, Central and South), see Appendix for classification of regions.
• for four target provinces: Ha Noi, Hai Phong, Quang Ninh and Ho Chi Minh City.
All women and men aged 15-49 years who were either permanent residents of the sampled households or visitors present in the household during the night before the survey were eligible to be interviewed in the survey. All women and men in the sample points of Hai Phong who were interviewed were asked to voluntarily give a blood sample for HIV testing. For youths aged 15-17, blood samples were drawn only after first obtaining consent from their parents or guardians.
(Refer Appendix A of the final survey report for details of sample implementation)
A total of 6,446 households were selected in the sample, of which 6,346 (98 percent) were found to be occupied at the time of the fieldwork. Occupied households include dwellings in which the household was present but no competent respondent was home, the household was present but refused the interview, and dwellings that were not found. Of occupied households, 6,337 were interviewed, yielding a household response rate close to 100 percent.
All women and men aged 15-49 years who were either permanent residents of the sampled households or visitors present in the household during the night before the survey were eligible to be interviewed in the survey. Within interviewed households, a total of 7,369 women aged 15-49 were identified as eligible for interview, of whom 7,289 were interviewed, yielding a response rate to the Individual interview of 99 percent among women. The high response rate was also achieved in male interviews. Among the 6,788 men aged 15-49 identified as eligible for interview, 6,707 were successfully interviewed, yielding a response rate of 99 percent.
Dates of Data Collection
Data Collection Mode
Data Collection Notes
Training courses for field staff were carried out in two locations. The first course took place in Ba Vi district of Ha Tay province, September 5-17, 2005, and the second course took place in My Tho city of Tien Giang province, September 12-24, 2005. A total of 79 candidates were trained. The courses consisted of introduction on interviewing skills and fieldwork procedures, detailed editing of questionnaires, mock interviews among trainees, and practice interviews in households outside the VPAIS sample points.
Testing of candidates at the end of the first week of training directed the selection of 72 candidates (36 men and 36 women) to form 12 data collection teams. Each team consisted of 1 male supervisor, 1 female field editor, 2 female interviewers and 2 male interviewers. Supervisors and field editors were trained in methods of editing, procedures for checking data quality, and logistics of field cooperation. In addition, team members assigned to Hai Phong province (12 in total) were trained on blood collection procedures. Trainers were senior staff from the VPAIS project, assisted by ORC Macro experts.
Two questionnaires were used in the survey, the Household Questionnaire and the Individual Questionnaire for women and men aged 15-49. The content of these questionnaires was based on the model AIDS Indicator Survey (AIS) questionnaires developed by the MEASURE DHS program implemented by ORC Macro.
In consultation with government agencies and local and international organizations, the GSO and NIHE modified the model questionnaires to reflect issues in HIV/AIDS relevant to Vietnam. These questionnaires were then translated from English into Vietnamese. The questionnaires were further refined after the pretest.
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, relationship to the head of the household, education, basic material needs, survivorship and residence of biological parents of children under the age of 18 years and birth registration of children under the age of 5 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 drinking water, type of toilet facilities, type of material used in the flooring of the house, and ownership of various durable goods, in order to allow for the calculation of a wealth index. The Household Questionnaire also collected information regarding ownership and use of mosquito nets.
The Individual Questionnaire was used to collect information from all women and men aged 15-49 years.
All questionnaires were administered in a face-to-face interview. Because cultural norms in Vietnam restrict open discussion of sexual behavior, there is concern that this technique may contribute to potential under-reporting of sexual activity, especially outside of marriage.
All aspects of VPAIS data collection were pre-tested in July 2005. In total, 24 interviewers (12 men and 12 women) were involved in this task. They were trained for thirteen days (including three days of fieldwork practice) and then proceeded to conduct the survey in the various urban and rural districts of Ha Noi. In total, 240 individual interviews were completed during the pretest. The lessons learnt from the pretest were used to finalize the survey instruments and logistical arrangements for the survey and blood collection.
The data processing of the VPAIS questionnaire began shortly after the fieldwork commenced. The first stage of data editing was done by the field editors, who checked the questionnaires for completeness and consistency. Supervisors also reviewed the questionnaires in the field. The completed questionnaires were then sent periodically to the GSO in Ha Noi by mail for data processing.
The office editing staff first checked that questionnaires of all households and eligible respondents had been received from the field. The data were then entered and edited using CSPro, a software package developed collaboratively between the U.S. Census Bureau, ORC Macro, and SerPRO to process complex surveys. All data were entered twice (100 percent verification). The concurrent processing of the data was a distinct advantage for data quality, as VPAIS staff was able to advise field teams of errors detected during data entry. The data entry and editing phases of the survey were completed by the end of December 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 2005 Vietnam Population and AIDS Indicator Survey (VPAIS) to minimize 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 2005 VPAIS 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 2005 VPAIS 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 2005 VPAIS is the ISSA Sampling Error Module. This module used the Taylor linearization method of variance estimation for survey estimates that are means or proportions.
(Refer Appendix B of the final survey report for details of sampling error calculation)
Data and Data Related Resources
World Bank Microdata Library
Disclaimer and copyrights
The user of the data acknowledges that the original collector of the data, the authorized distributor of the data, and the relevant funding agency bear no responsibility for use of the data or for interpretations or inferences based upon such uses.
DDI Document ID
World Bank, Development Economics Data Group
Documentation of the study
Date of Metadata Production
DDI Document version
Version 01 (September 2013). Metadata in this DDI is excerpted from "Vietnam Population and AIDS Indicator Survey (AIS) 2005" Report.