The 2001-2002 Zambia Demographic and Health Survey (ZDHS) was carried out by the Central Statistical Office and the Central Board of Health. It is a nationally representative sample of 7,658 women age 15-49 and 2,145 men age 15-59. The principal objective of the survey was to provide data to policymakers and planners on the population and health situation in Zambia. Most of the information collected in the 2001-2002 ZDHS represents updated estimates of basic demographic and health indicators covered in the 1992 ZDHS and 1996 ZDHS surveys.
The 2001-2002 ZDHS was conducted by the Central Statistical Office (CSO) and the Central Board of Health (CBoH). ORC Macro of Calverton, Maryland provided technical assistance to the project through its contract with the U.S. Agency for International Development (USAID). Funding for the survey was supplied by ORC Macro (from USAID), the Government of Japan through a trust fund managed by the United Nations Development Programme (UNDP) and through bilateral agreements between the Government of the Republic of Zambia and the United Nations Population Fund (UNFPA), and the Danish International Development Agency (DANIDA).
The primary objectives of the ZDHS are:
- To collect up-to-date information on fertility, infant and child mortality and family planning;
- To collect information on health-related matters such as breastfeeding, antenatal care, children's immunisations and childhood diseases;
- To assess the nutritional status of mothers and children;
- To support dissemination and utilisation of the results in planning, managing and improving family planning and health services in the country;
- To enhance the survey capabilities of the institutions involved in order to facilitate the implementation of surveys of this type in the future; and
- To document current epidemics of sexually transmitted infections and HIV/AIDS through use of specialised modules.
Specifically, the 2001-2002 ZDHS collected detailed information on fertility and family planning, child mortality and maternal mortality, maternal and child health and nutritional status, and knowledge, awareness and behaviour regarding HIV/AIDS and other sexually transmitted infections. New features of the 20012002 ZDHS include the collection of information on violence against women and testing of individuals for HIV and syphilis.
Kind of data
Sample survey data
The DHS 2001-02 is a nationally representative survey. The primary focus of the 2001 Zambia DHS is to provide estimates of key population and health indicators, including fertility and mortality rates, for the country as a whole, and for urban and rural areas separately. Also, the sample was designed to provide estimates of key variables for the nine provinces, namely, 1) Central, 2) Copperbelt, 3) Eastern, 4) Luapula, 5) Lusaka, 6) Northern, 7) North-Western, 8) Southern, and 9) Western. In addition, the sample provides basic information for a total of 12 combined districts (not each separately) that are the special focus of the Zambia Integrated Health Programme (Livingstone, Kalomo, Chibombo, Kabwe Urban, Ndola Urban, Kitwe, Chipata, Lundazi, Chama, Kasama, Samfya, and Mwense).
Unit of analysis
- women age 15-49
- Men age 15-59
- Children under five years
The population covered by the 2001-2002 ZDHS is defined as the universe of all women age 1549 in Zambia and all men age 15-59. A sample of households was selected and all women age 15-49 identified in the households were interviewed. In addition, in a subsample of one-third of all the households selected for the ZDHS, all men 15-59 were eligible to be interviewed if they were either permanent residents or visitors present in the household on the night before the survey.
Producers and sponsors
Central Statistical Office
Central Board of Health (CBoH)
ORC Macro of Calverton
Agency for International Development
Government of Japan
United Nations Development Programme
Government of the Republic of Zambia
United Nations Population Fund
Danish International Development Agency
The 2001-2002 Zambia Demographic and Health Survey (ZDHS) is a comprehensive nationally representative population and health survey carried out by the Central Statistical Office in partnership with the Central Board of Health. ORC Macro provided financial and technical assistance for the survey through the USAID-funded MEASURE DHS+ programme. Additional funding for the ZDHS was received from the Government of Japan, UNFPA, and DANIDA. The principal objective of the ZDHS is to provide current and reliable data on fertility and family planning behaviour, child mortality, children's nutritional status, the utilization of maternal, child health services, knowledge and prevalence of HIV and syphilis.
The Zambia DHS collected demographic and health information from a nationally representative sample of women and men age 15-49 and 15-59, respectively. The primary focus of the 2001 Zambia DHS is to provide estimates of key population and health indicators, including fertility and mortality rates, for the country as a whole, and for urban and rural areas separately. Also, the sample was designed to provide estimates of key variables for the nine provinces, namely, 1) Central, 2) Copperbelt, 3) Eastern, 4) Luapula, 5) Lusaka, 6) Northern, 7) North-Western, 8) Southern, and 9) Western. In addition, the sample provides basic information for a total of 12 combined districts (not each separately) that are the special focus of the Zambia Integrated Health Programme (Livingstone, Kalomo, Chibombo, Kabwe Urban, Ndola Urban, Kitwe, Chipata, Lundazi, Chama, Kasama, Samfya, and Mwense).
Zambia is divided into nine provinces. In turn, each province is subdivided in districts, each district into constituencies, and each constituency into wards. In addition to these administrative units, during the 2000 population census, each ward was subdivided into convenient areas called census supervisory areas (CSAs), and in turn each CSA into standard enumeration areas (SEAs). In total Zambia has 72 districts, 150 constituencies, 1,289 wards, about 4,400 CSAs, and about 16,400 SEAs. Preliminary information on the counts of households and population, as well as cartographic materials were available from the 2000 population census for the SEAs. Therefore, the sample frame for this survey was the list of SEAs developed from the 2000 population census.
In the preliminary census frame, the SEAs were grouped by CSAs, by CSAs within a ward, by wards within a constituency, by constituencies within a district and by districts within a province for purposes of the ZDHS. The SEAs were further stratified separately by urban and rural areas within each province.
The primary sampling unit (PSU), the cluster for the 2001-2002 ZDHS, is defined on the basis of SEAs from the census frame. A minimum requirement of 85 households for the cluster size was imposed in the design. If an SEA did not have 85 households, it was combined with an adjacent SEA; thus, the ZDHS cluster comprised one or more SEAs. The number of clusters in each district was not allocated proportional to the total population due to the need to present estimates by each of the nine provinces. Zambia is a country where two-thirds of the population reside in rural areas, and one-third in urban areas.
The target for the 2001-2002 ZDHS sample was 8,000 completed interviews. Based on the level of non-response found in the 1996 ZDHS, to achieve this target, approximately 8,200 households were selected, with all women age 15-49 being interviewed. The target was to reach a minimum of 750 completed interviews per province. In each province the number of households was distributed proportionately among the urban and rural areas. Table A.2 shows the distribution of about 8,200 households by province.
The urban-rural distribution was also considered in distributing the sample. The selected households were distributed in 320 clusters in Zambia, 100 clusters in the urban areas, and 220 clusters in the rural areas.
Under this final allocation, the 12 combined districts of the Zambia Integrated Health Programme have 77 selected clusters, 36 in urban areas and 41 in rural areas.
The 2001-2002 ZDHS sample was selected using a stratified two-stage cluster design consisting of 320 clusters, 100 in urban and 220 in rural areas. Once the number of households was allocated to each combination of province by urban and rural areas, the number of clusters was calculated based on an average sample take of 25 completed interviews among women 15-49 years. In each urban or rural area in a given province, clusters were selected systematically with probability proportional to the number of households in each cluster.
Response rates are a source of concern because high non-response may affect the reliability of the results. A total of 8,050 households were selected in the sample, of which 7,260 were found at the time of the fieldwork. The shortfall is largely due to some structures being vacant. Of the 7,260 existing households, 7,126 were successfully interviewed, yielding a household response rate of 98 percent.
In the households interviewed in the survey, a total of 7,944 eligible women were identified; interviews were completed with 7,658 of these women, yielding a response rate of 96 percent. With regard to the male survey results, 2,418 eligible men were identified in the subsample of households selected for the male survey, of which 2,145 were successfully interviewed, yielding a response rate of 89 percent. The response rates are lower for the urban than for rural sample, especially for men.
There is no difference by urban-rural residence in the overall response rate for eligible women; however rural men are more likely than urban men to have completed the interview (89.4 percent and 83.0 percent, respectively). The overall response rate among women by province is relatively high and ranges from 90.1 percent for Western province to 97.3 for Luapula province. The overall response rate for men ranges from 78.1 for Western province to 96.9 for Luapula province.
Compared with the 1996 ZDHS, there has been a slight decline in response rates. In the 1996 survey, the response rates were 99 percent for households, 97 percent for women, and 91 percent for men (CSO, MOH,and Macro International, 1997).
The principal reason for non-response among both eligible men and women was the failure to find individuals at home despite repeated visits to the household. The substantially lower response rate for men reflects the more frequent and longer absences of men from the household, principally related to their employment and life style.
Dates of collection
Mode of data collection
Data collection supervision
Each team consisted of one team supervisor, one field editor, three to four female interviewers, one male interviewer, one nurse/nurse counselor, one lab technician, and one driver. Six staff assigned from the CSO coordinated and supervised fieldwork activities. They were assisted by staff from the TDRC and the University of Zambia Demography Division. ORC Macro participated in field supervision for interviews, height and weight measurements, and blood collection and testing.
Three questionnaires were used for the 2001-2002 ZDHS:
a) the Household Questionnaire,
b) the Women's Questionnaire
c) the Men's Questionnaire.
The contents of these questionnaires were based on the model questionnaires developed by the MEASURE DHS+ programme for use in countries with low levels of contraceptive use.
In consultation with technical institutions, local and international organisations, the CSO modified the DHS model questionnaires to reflect relevant issues in population, family planning and other health issues in Zambia. A series of questionnaire design meetings were organised by the CSO with the assistance of ORC Macro, and the inputs generated in these meetings were used to produce the first draft of the ZDHS questionnaires. These questionnaires were translated from English into the seven major languages, namely Bemba, Kaonde, Lozi, Lunda, Luvale, Nyanja, and Tonga.
a) 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 his or her 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 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 height and weight measurements of women 15-49 and children under the age of 6, and, where syphilis and HIV testing was conducted, to record the respondents' consent to the testing. In order to maintain confidentiality, separate forms were used for recording the results of the syphilis and HIV testing.
b) The Women's Questionnaire was used to collect information from all women age 15-49. These women were asked questions on the following topics:
- Background characteristics (education, residential history, media exposure, etc.)
- Knowledge and use of family planning methods
- Fertility preferences
- Antenatal and delivery care
- Breastfeeding and infant feeding practices
- Vaccinations and childhood illnesses
- Marriage and sexual activity
- Woman's work and husband's background characteristics
- Infant and child feeding practices
- Childhood mortality
- Awareness and behaviour regarding AIDS and other sexually transmitted infections (STIs)
- Adult mortality including maternal mortality.
The Women's Questionnaire included a series of questions to obtain information on women's experience of domestic violence. These questions were administered to one woman per household. In households with two or more eligible women, special procedures were followed in order to ensure the random selection of this woman.
c) The Men's Questionnaire was administered to all men age 15-59 living in every third household in the ZDHS sample. The Men's Questionnaire collected much of the same information found in the Women's Questionnaire, but was shorter because it did not contain a reproductive history or questions on maternal and child health, nutrition, or maternal mortality.
Central Statistical Office
The processing of the ZDHS results began shortly after the fieldwork commenced. Completed questionnaires were returned periodically from the field to CSO offices in Lusaka, where they were entered and edited by data processing personnel who were specially trained for this task. The concurrent processing of the data was an advantage because CSO was able to advise field teams of problems detected during the data entry. TDRC provided the results of the syphilis and HIV testing to CSO for entry and editing. The data entry and editing phase of the survey was completed in August 2002.
Sampling errors can be evaluated statistically. The sample of respondents selected in the 2001-2002 ZDHS 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 2001-2002 ZDHS sample is the result of a multistage stratified design, and consequently, it was necessary to use more complex formulas. The computer software used to calculate sampling errors for the 2001-2002 ZDHS is the ISSA Sampling Error Module (ISSAS). This module used the Taylor linearization 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.
In addition to the standard error, ISSAS computes the design effect (DEFT) for each estimate, which is defined as the ratio between the standard error using the given sample design and the standard error that would result if a simple random sample had been used. A DEFT value of 1.0 indicates that the sample design is as efficient as a simple random sample, while a value greater than 1.0 indicates the increase in the sampling error due to the use of a more complex and less statistically efficient design. ISSAS also computes the relative error and confidence limits for the estimates.
Sampling errors for the 2001-2002 ZDHS women and men are calculated for selected variables considered to be of primary interest including HIV and syphilis prevalence. The results are presented in an appendix to the Final Report for the country as a whole, for urban and rural areas, and for each of the 9 subdomains (provinces) in the country. For each variable, the type of statistic (mean, proportion, or rate) and the base population are given in Table B.1 of the Final Report. Tables B.2 to B.13 present the value of the statistic (R), its standard error (SE), the number of unweighted (N) and weighted (WN) cases, the design effect (DEFT), the relative standard error (SE/R), and the 95 percent confidence limits (R±2SE) for each variable. The DEFT is considered undefined when the standard error considering simple random sample is zero (when the estimate is close to 0 or 1).
In general, the relative standard error for most estimates for the country as a whole is small, except for estimates of very small proportions. There are some differentials in the relative standard error for the estimates of subpopulations. For example, for the variable “currently using any contraceptive method” for currently married women age 15-49, the relative standard errors as a percentage of the estimated mean for the whole country, for urban areas, and for rural areas are 2.5 percent, 3.6 percent, and 3.2 percent, respectively.
The confidence interval (e.g., as calculated for “currently using any contraceptive method” for currently married women age 15-49) can be interpreted as follows: the overall national sample proportion is 0.342 and its standard error is 0.009. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e. 0.342±2(0.009). There is a high probability (95 percent) that the true average proportion of contraceptive use for currently married women age 15-49 is between 0.325 and 0.359.
Other forms of data appraisal
Nonsampling errors are the result 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 2001-2002 ZDHS to minimise this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.
Use of the dataset must be acknowledged using a citation which would include:
- the Identification of the Primary Investigator
- the title of the survey (including country, acronym and year of implementation)
- the survey reference number
- the source and date of download
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.