Demographic and Health Survey 1998 - South Africa

Abstract
---------------------------

The 1998 South Africa Demographic and Health Survey (SADHS) is the first study of its kind to be conducted in South Africa and heralds a new era of reliable and relevant information in South Africa. The SADHS, a nation-wide survey has collected information on key maternal and child health indicators, and in a first for international demographic and health surveys, the South African survey contains data on the health and disease patterns in adults.

Plans to conduct the South Africa Demographic and Health Survey go as far back as 1995, when the Department of Health National Health Information Systems of South Africa (NHIS/SA) committee, recognised serious gaps in information required for health service planning and monitoring.

Fieldwork was conducted between late January and September 1998, during which time 12,247 households were visited, 17,500 people throughout nine provinces were interviewed and 175 interviewers were trained to interview in 11 languages.

The aim of the 1998 South Africa Demographic and Health Survey (SADHS) was to collect data as part of the National Health Information System of South Africa (NHIS/SA). The survey results are intended to assist policymakers and programme managers in evaluating and designing programmes and strategies for improving health services in the country. A variety of demographic and health indicators were collected in order to achieve the following general objectives:

(i) To contribute to the information base for health and population development programme management through accurate and timely data on a range of demographic and health indicators.
(ii) To provide baseline data for monitoring programmes and future planning.
(iii) To build research and research management capacity in large-scale national demographic and health surveys.

The primary objective of the SADHS is to provide up-to-date information on:
- basic demographic rates, particularly fertility and childhood mortality levels,
- awareness and use of contraceptive methods,
- breastfeeding practices,
- maternal and child health,
- awareness of HIV/AIDS,
- chronic health conditions among adults,
- lifestyles that affect the health status of adults, and
- anthropometric indicators.

Geographic coverage
---------------------------

It was designed principally to produce reliable estimates of demographic rates (particularly fertility and childhood mortality rates), of maternal and child health indicators, and of contraceptive knowledge and use for the country as a whole, the urban and the non-urban areas separately, and for the nine provinces.

Analysis unit
---------------------------

- Household
- Women age 15-49
- Men age 15 and above

Universe
---------------------------

The 1998 South African Demographic and Health Survey (SADHS) covered the population living in private households in the country.

Kind of data
---------------------------

Sample survey data

Sampling procedure
---------------------------

The 1998 South African Demographic and Health Survey (SADHS) covered the population living in private households in the country. The design for the SADHS called for a representative probability sample of approximately 12,000 completed individual interviews with women between the ages of 15 and 49. It was designed principally to produce reliable estimates of demographic rates (particularly fertility and childhood mortality rates), of maternal and child health indicators, and of contraceptive knowledge and use for the country as a whole, the urban and the non-urban areas separately, and for the nine provinces. As far as possible, estimates were to be produced for the four South African population groups. Also, in the Eastern Cape province, estimates of selected indicators were required for each of the five health regions.

In addition to the main survey of households and women 15-49 that followed the DHS model, an adult health module was administered to a sample of adults aged 15 and over in half of the households selected for the main survey. The adult health module collected information on oral health, occupational hazard and chronic diseases of lifestyle.

SAMPLING FRAME

The sampling frame for the SADHS was the list of approximately 86,000 enumeration areas (EAs) created by Central Statistics (now Statistics South Africa, SSA) for the Census conducted in October 1996. The EAs, ranged from about 100 to 250 households, and were stratified by province, urban and non-urban residence and by EA type. The number of households in the EA served as a measure of size of the EA.

CHARACTERISTICS OF THE SADHS SAMPLE

The sample for the SADHS was selected in two stages. Due to confidentiality of the census data, the sampling was carried out by experts at the CSS according to specifications developed by members of the SADHS team. Within each stratum a two stage sample was selected. The primary sampling units (PSUs), corresponded to the EAs and will be selected with probability proportional to size (PPS), the size being the number of households residing in the EA, or where this was not available, the number of census visiting points in the EA. This led to 972 PSUs being selected for the SADHS (690 in urban areas and 282 in non-urban areas. Where provided by SSA, the lists of visiting points together with the households found in these visiting points, or alternatively a map of the EA which showed the households, was used as the frame for second-stage sampling to select the households to be visited by the SADHS interviewing teams during the main survey fieldwork. This sampling was carried out by the MRC behalf of the SADHS working group. If a list of visiting points or a map was not available from SSA, then the survey team took a systematic sample of visiting points in the field. In an urban EA ten visiting points were sampled, while in a non-urban EA twenty visiting points were sampled. The survey team then interviewed the household in the selected visiting point. If there were two households in the selected visiting point, both households were interviewed. If there were three or more households, then the team randomly selected one household for interview. In each selected household, a household questionnaire was administered; all women between the ages of 15 and 49 were identified and interviewed with a woman questionnaire. In half of the selected households (identified by the SADHS working group), all adults over 15 years of age were also identified and interviewed with an adult health questionnaire.

SAMPLE ALLOCATION

Except for Eastern Cape, the provinces were stratified by urban and non-urban areas, for a total of 16 sampling strata. Eastern Cape was stratified by the five health regions and urban and non-urban within each region, for a total of 10 sampling strata. There were thus 26 strata in total.

Originally, it was decided that a sample of 9,000 women 15-49 with complete interviews allocated equally to the nine provinces would be adequate to provide estimates for each province separately; results of other demographic and health surveys have shown that a minimum sample of 1,000 women is required in order to obtain estimates of fertility and childhood mortality rates at an acceptable level of sampling errors. Since one of the objectives of the SADHS was to also provide separate estimates for each of the four population groups, this allocation of 1,000 women per province would not provide enough cases for the Asian population group since they represent only 2.6 percent of the population (according to the results of the 1994 October Household Survey conducted by SSA). The decision was taken to add an additional sample of 1,000 women to the urban areas of KwaZulu-Natal and Gauteng to try to capture as many Asian women as possible as Asians are found mostly in these areas. A more specific sampling scheme to obtain an exact number of Asian women was not possible for two reasons: the population distribution by population group was not yet available from the 1996 census and the sampling frame of EAs cannot be stratified by population group according to SSA as the old system of identifying EAs by population group has been abolished.

An additional sample of 2,000 women was added to Eastern Cape at the request of the Eastern Cape province who funded this additional sample. In Eastern Cape, results by urban and non-urban areas can be given. Results of selected indicators such as contraceptive knowledge and use can also be produced separately for each of the five health regions but not for urban/non-urban within health region.

Result shows the allocation of the target sample of 12,000 women by province and by urban/non­urban residence. Within each province, the sample is allocated proportionately to the urban/non-urban areas.

In the above allocation, the urban areas of KwaZulu-Natal have been oversampled by about 57 percent while those of Gauteng have been oversampled by less than 1 percent. For comparison purposes, it shows a proportional allocation of the 12,000 women to the nine provinces that would result in a completely self-weighting sample but does not allow for reliable estimates for at least four provinces (Northern Cape, Free State, Mpumalanga and North-West).

The number of households to be selected for each stratum was calculated as follows:

- According to the 1994 October Household Survey, the estimated number of women 15-49 per households is 1.2. The overall response rate was assumed to be 80 percent, i.e., of the households selected for the survey only 90 percent would be successfully interviewed, and of the women identified in the households with completed interviews, only 90 percent would have a complete woman questionnaire. Using these two parameters in the above equation, we would expect to select approximately 12,500 households in order to yield the target sample of women.

- The number of sample points (or clusters) to be selected for each stratum is calculated by dividing the number of households in the stratum by the average "take" in the cluster. In SADHS, each cluster will correspond to a census EA. Analytical studies of surveys of the same nature suggest that the optimum number of women to be interviewed is around 20-25 in each urban cluster and 30-35 in each non-urban cluster. However it was decided that these numbers would be lower for the SADHS, given the practice of small cluster "take" in surveys conducted in South Africa and that the field cost is generally reasonable. If we selected 10 households in each urban cluster and 20 households in each non-urban cluster, the distribution of sample points or EAs would be as follows:

- Some rearrangement was then necessary so that in each stratum there was an even number of EAs. This is recommended for the purpose of calculating sampling errors using Taylor linearization in which the first step is to form pairs of homogeneous clusters.
In the Eastern Cape, the sample was distributed equally among the five health regions since estimates are required at the level of health region. Within each health region the sample was distributed proportionally to urban/non-urban according to the distribution of population in 1993. Table A7 shows the proposed number of EAs to be selected.

- In allocating the number of EAs to the five health regions of the Eastern Cape, we tried to follow the rule of an even number of clusters per sampling stratum while aiming for a regional sample of approximately 600 households (resulting in about 600 women aged 15-49).

STRATIFICATION AND SYSTEMATIC SELECTION OF EAS

Stratification and selection of the EAs for the SADHS was done by CSS according to the following specifications. Explicit stratification of the EAs was by province and by urban/non-urban within province except in Eastern Cape where the strata were the urban and non-urban areas of each of the five health regions. EAs that contain only institutions such as prisons and mine hostels were excluded from the sampling frame. Within each EA type, the EAs were ordered according to geographic or administrative units as adopted by SSA for the census. The number of EAs were then selected independently within each explicit stratum and with probability proportional to size. The measure of size used for selection was the number of households enumerated in each EA by the census.
The selection procedure that SSA used in each explicit stratum was as follows:
1. calculating the selection interval for the EAs:
where Mi is the size of the stratum (total number of households or population in the stratum according to the census) and a is the number of EAs to be selected in the stratum;
2. calculating the cumulated size of each EA;
3. calculating the series of sampling numbers R, R+I, R+2I, ..., R+(a-1)I, where R is a random number between 1 and I;
4. comparing each sampling number with the cumulated sizes.

The first EA to be selected was the first EA on the list whose cumulated size was equal or greater than the first sampling number. The second EA to be selected was the next EA on the list (after the first selected one) whose cumulated size was equal or greater than the second sampling number, and so on.

Mode of data collection
---------------------------

Face-to-face

Research instrument
---------------------------

The survey utilised three questionnaires: a) a Household Questionnaire, b) a Woman's Questionnaire and c) an Adult Health Questionnaire. The contents of the first two were adapted from the DHS Model Questionnaires to meet the needs of the national and provincial Departments of Health. The Adult Health Questionnaire was developed to obtain information regarding the health of adults. Indicators listed in the preliminary Year 2000 Goals, Objectives and Indicators document were included where a household survey was the appropriate mechanism for collecting the information.

a) The Household Questionnaire was used to list all the usual members and visitors in the selected households. Basic information was collected on the characteristics of each person listed, including his/her age, sex, education and relationship to the head of the household. Information was collected about social grants, work status and injuries experienced in the last month. An important purpose of the Household Questionnaire was to identify women and adults who were eligible for interview. In addition, information was collected about the dwelling itself, such as the source of water, type of toilet facilities, material used to construct the house and ownership of various consumer goods.

b) The Woman's Questionnaire was used to collect information from all women age 15-49. These women were asked questions on the following topics:
- Background characteristics (age, education, race, etc.)
- Pregnancy history
- Knowledge and use of contraceptive methods
- Antenatal and delivery care
- Breastfeeding and weaning practices
- Child health and immunisation
- Marriage and recent sexual activity
- Fertility preferences
- Violence against women
- Knowledge of HIV/AIDS
- Maternal mortality
- Husband's background and respondent's work

c) In every second household, all men and women aged 15 and above were eligible to be interviewed with the Adult Health Questionnaire. The respondents were asked questions on:
- Recent utilisation of health services,
- Family medical history,
- Clinical conditions,
- Dental health,
- Occupational health,
- Medications taken,
- Habits and lifestyles, Anthropometric measurements, and, Blood pressure and lung function test.

Cleaning operations
---------------------------

All completed questionnaires for the SADHS were submitted to the provincial offices of King Finance (who were in partnership with the Centre for Health Systems Research at the University of the Free State), which then forwarded them to the MRC for data processing. The questionnaires were processed at the Medical Research Council offices in Cape Town.

The processing operation consisted of office editing, coding of open-ended questions, initial data entry and subsequent re-entry of all questionnaires to ensure correct data-capture, and finally editing inconsistencies found by the computer program. The SADHS data entry and editing programs were written using ISSA (Integrated System for Survey Analysis) by staff from Macro International. A small proportion of the questionnaires were returned to the field to complete missing information. Data processing commenced in mid-March 1998 and was completed in October 1998.

Response rate
---------------------------

Of the total 972 PSUs that were selected, fieldwork was not implemented in three PSUs due to concerns about the safety of the interviewers and the questionnaires for another three PSUs were lost in transit. The data file contains information for a total of 966 PSUs. A total of 12,860 households was selected for the sample and 12,247 were successfully interviewed. The shortfall is primarily due to refusals and to dwellings that were vacant or in which the inhabitants had left for an extended period at the time they were visited by interviewing teams.

Of the 12,638 households occupied 97 percent were successfully interviewed. In these households, 12,327 women were identified as eligible for the individual women's interview (15-49) and interviews were completed with 11,735 or 95 percent of them. In the one half of the households that were selected for inclusion in the adult health survey 14,928 eligible adults age 15 and over were identified of which 13,827 or 93 percent were interviewed. The principal reason for non-response among eligible women and men was the failure to find them at home despite repeated visits to the household. The refusal rate was about 2 percent.

Sampling error estimates
---------------------------

Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the SADHS 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 SADHS sample is the result of a two-stage stratified design, and, consequently, it was necessary to use more complex formulae. The computer software used to calculate sampling errors for the SADHS 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 Jackknife repeated replication method derives estimates of complex rates from each of several replications of the parent sample, and calculates standard errors for these estimates using simple formulae. Each replication considers all but one clusters in the calculation of the estimates. Pseudo-independent replications are thus created. In the SADHS, there were 966 non-empty clusters. Hence, 965 replications were created.

Sampling errors for the SADHS are calculated for selected variables considered to be of primary interest. The results are presented in an appendix to the Final Report for the country as a whole, for urban and rural areas, for each of the 9 provinces, and for each of the four population groups. 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.17 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 the case of the total fertility rate, the number of unweighted cases is not relevant since there is no known unweighted value for woman-years of exposure to childbearing.

The confidence interval (e.g., as calculated for children ever born to women age 15-49) can be interpreted as follows: the overall average from the national sample is 1.939 and its standard error is .024. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e., 1.939±2×.024. There is a high probability (95 percent) that the true average number of children ever born to all women aged 15 to 49 is between 1.891 and 1.987. Sampling errors are analysed for the national sample and for two separate groups of estimates: (1) means and proportions, and (2) complex demographic rates. The relative standard errors (SE/R) for the means and proportions range between 0 percent and 34 percent with an average of 4.6 percent; the highest relative standard errors are for estimates of very low values (e.g., currently using periodic abstinence among currently married women). If estimates of very low values (less than 10 percent) were removed, then the average drops to 2.1 percent. So in general, the relative standard error for most estimates for the country as a whole is small, except for estimates of very small proportions. The relative standard error for the total fertility rate is small, 2.7 percent. However, for the mortality rates, the average relative standard error is higher, 8.2 percent.

There are differentials in the relative standard error for the estimates of sub-populations. For example, for the variable with standard 6 or higher, the relative standard errors as a percent of the estimated mean for the whole country, for the rural areas, and for Northern Cape Province are 1.0 percent, 2.3 percent, and 4.9 percent, respectively.

For the total sample, the value of the design effect (DEFT) averaged over all variables is 1.33, which means that due to multi-stage clustering of the sampling error is increased by a factor of 1.33 over that in an equivalent simple random sample.

Data appraisal
---------------------------

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 SADHS to minimise this type of error, non-sampling errors are impossible to avoid and difficult to evaluate statistically.

摘要
---------------------------
1998年南非人口与健康调查（SADHS）是南非首次进行此类研究，标志着南非开始进入一个可靠且相关的信息时代。SADHS作为一项全国性调查，收集了关于关键的母亲和儿童健康指标的信息，在国际人口与健康调查中首次，南非调查包含了成年人健康和疾病模式的数据。

计划进行南非人口与健康调查可以追溯到1995年，当时南非卫生部国家卫生信息系统（NHIS/SA）委员会认识到在卫生服务规划和监控所需信息方面存在严重差距。

实地调查于1998年1月底至9月进行，期间访问了12,247个家庭，在九个省份的17,500人接受了访谈，并培训了175名访谈员，以便用11种语言进行访谈。

1998年南非人口与健康调查（SADHS）的目的是作为南非国家卫生信息系统（NHIS/SA）的一部分收集数据。调查结果旨在帮助政策制定者和项目管理者评估和设计改善国家卫生服务的计划与策略。收集了各种人口与健康指标，以实现以下总体目标：

(i) 通过一系列人口与健康指标的准确和及时数据，为健康和人口发展计划管理提供信息基础。
(ii) 为监测计划和未来规划提供基线数据。
(iii) 增强在大规模国家人口与健康调查中的研究和研究管理能力。

SADHS的主要目标是提供以下最新信息：
- 基本的人口统计指标，尤其是生育率和儿童死亡率水平。
- 避孕方法的认知和使用。
- 哺乳实践。
- 母亲和儿童健康。
- 对艾滋病/艾滋病的认知。
- 成人的慢性健康状况。
- 影响成人健康状况的生活方式。
- 人体测量指标。

地理覆盖范围
---------------------------
该调查旨在主要产生关于全国、城市和农村地区以及九个省份的可靠的人口统计指标估计值，特别是生育率和儿童死亡率，以及母亲和儿童健康指标和避孕知识的估计值。

分析单位
---------------------------
- 家庭
- 15-49岁的女性
- 15岁及以上的男性

总体
---------------------------
1998年南非人口与健康调查（SADHS）涵盖了国家中私人家庭中的所有人口。

数据类型
---------------------------
样本调查数据

抽样程序
---------------------------
1998年南非人口与健康调查（SADHS）涵盖了国家中私人家庭中的所有人口。SADHS的设计要求对约12,000名15至49岁女性的代表性概率样本进行约12,000次完成的个人访谈。其主要目的是产生关于全国、城市和农村地区以及九个省份的可靠的人口统计指标估计值，特别是生育率和儿童死亡率，以及母亲和儿童健康指标和避孕知识的估计值。尽可能产生针对四个南非人口群体的估计值。在东开普省，需要为每个五个健康区域提供选定指标的估计值。

除了东开普省外，省份根据城市和农村地区进行了分层，共分为16个抽样层。东开普省根据五个健康区域和每个区域内的城市和农村地区进行了分层，共分为10个抽样层。因此，总共有26个层。

原始决定是为每个省份分配9,000名15-49岁女性的样本，这些样本将平均分配到九个省份，足以提供每个省份的估计值。其他人口与健康调查的结果表明，需要至少1,000名女性的样本才能以可接受的抽样误差水平获得生育率和儿童死亡率估计值。由于SADHS的一个目标是为四个人口群体中的每个群体提供单独的估计值，因此每个省份分配1,000名女性的样本将不足以提供亚洲人口群体的案例，因为它们只占人口的2.6%（根据南非统计局1994年10月进行的家庭调查结果）。因此，决定在夸祖鲁-纳塔尔省和豪登省的城市地区额外增加1,000名女性的样本，以尽可能多地捕捉亚洲女性，因为亚洲人主要居住在这些地区。

东开普省根据东开普省的要求额外增加了2,000名女性的样本，东开普省资助了这部分额外样本。在东开普省，可以提供城市和农村地区的结果。还可以为每个五个健康区域单独提供选定指标（如避孕知识的认知和使用）的结果，但不能为健康区域内的城市/农村提供结果。

结果显示了按省份和城市/农村居住地分配的目标样本12,000名女性的分配情况。在每个省份内，样本按比例分配到城市/农村地区。

在上述分配中，夸祖鲁-纳塔尔省的城市地区抽样过多约57％，而豪登省的抽样过多不到1％。为了进行比较，显示了将12,000名女性按比例分配到九个省份的情况，这将产生一个完全自加权样本，但不能为至少四个省份（北开普、自由州、姆普马兰加和西北省）提供可靠的估计值。

为每个层选择要选择的户数按以下方式计算：
- 根据1994年10月家庭调查，每户估计有1.2名15-49岁的女性。假设总体响应率为80％，即所选的每个家庭中只有90％将被成功访谈，在完成访谈的家庭中，只有90％的女性将完成女性问卷。

抽样框架
---------------------------
SADHS的抽样框架是由中央统计局（现为南非统计局，SSA）为1996年10月进行的普查创建的大约86,000个普查区域（EA）的名单。

SADHS样本的特征
---------------------------
SADHS的样本是在两个阶段选择的。由于人口普查数据的保密性，抽样由CSS的专家根据SADHS团队成员制定的规范进行。

数据收集方式
---------------------------
面对面

研究工具
---------------------------
调查使用了三种问卷：a）家庭问卷，b）女性问卷和c）成人健康问卷。前两个问卷的内容是根据国家卫生部和省级卫生部门的需求改编的DHS模型问卷。成人健康问卷是为了获取有关成人健康的信息而开发的。初步的2000年目标、目标和指标文件中列出的指标包括在家庭调查中是收集信息的适当机制。

a）家庭问卷用于列出所选家庭的所有常住成员和访客。收集了有关所列每个人的特征的基本信息，包括年龄、性别、教育以及与家庭户主的关系。收集了有关社会补助、工作状况和上个月经历的伤害的信息。家庭问卷的一个重要目的是确定有资格接受访谈的女性和成人。此外，还收集了有关住宅本身的信息，例如水源、厕所设施类型、房屋建造材料和各种消费品的所有权。

b）女性问卷用于收集所有15-49岁女性的信息。这些女性被问及以下主题：
- 背景（年龄、教育、种族等）
- 怀孕史
- 避孕方法的认知和使用
- 产前和分娩护理
- 哺乳和断奶实践
- 儿童健康和免疫
- 婚姻和最近的活动
- 生育偏好
- 对女性的暴力
- 对艾滋病/艾滋病的认知
- 母亲死亡率
- 丈夫的背景和受访者的工作

c）在所选家庭中的一半，所有15岁及以上的男性和女性都有资格接受成人健康问卷的访谈。受访者被问及以下问题：
- 最近使用卫生服务的情况
- 家庭医疗史
- 临床状况
- 口腔健康
- 职业健康
- 使用的药物
- 习惯和生活方式
- 人体测量测量，以及血压和肺功能测试。

数据清理操作
---------------------------
所有完成的SADHS问卷都提交给了金财省办事处（当时与南非自由州健康系统研究中心合作），然后将其转发给了MRC进行数据处理。问卷在开普敦的医学研究理事会办公室进行处理。

数据处理操作包括办公室编辑、开放式问题的编码、初始数据录入以及随后对所有问卷的重新录入以确保正确的数据捕获，最后编辑计算机程序发现的差异。SADHS数据录入和编辑程序由Macro International的员工使用ISSA（综合调查分析系统）编写。

响应率
---------------------------
在总共972个选定的PSU中，由于对访谈员和问卷的安全性存在担忧，在三个PSU中没有实施实地调查。数据文件包含966个PSU的信息。总共选择了12,860户家庭作为样本，其中12,247户成功接受了访谈。短缺主要是由于拒绝和受访者在访问时已空置或长时间离开住所。

在12,638户有人的家庭中，97％成功接受了访谈。在这些家庭中，确定了12,327名有资格接受个人女性访谈（15-49岁）的女性，其中11,735人或95％接受了访谈。在一半被选入成人健康调查的家庭中，确定了14,928名有资格的15岁及以上的成人，其中13,827人或93％接受了访谈。合格女性和男性未响应的主要原因是在反复访问家庭后未能找到他们。拒绝率约为2％。

抽样误差估计
---------------------------
抽样误差可以从统计上进行评估。SADHS中选定的受访者样本只是从同一人口中可以选出的许多样本之一，使用相同的设计和预期规模。每个样本都会产生与实际样本选择结果略有不同的结果。抽样误差是衡量所有可能样本之间差异的指标。尽管变异程度无法精确知道，但可以从调查结果中进行估计。

抽样误差通常以特定统计量（平均值、百分比等）的标准误差来衡量，这是方差的平方根。标准误差可用于计算置信区间，在这个区间内可以合理地假设总体中真实值的范围。

如果受访者样本被选为简单随机样本，就可以使用计算抽样误差的简单公式。然而，SADHS样本是两阶段分层设计的产物，因此有必要使用更复杂的公式。用于计算SADHS抽样误差的计算机软件是ISSA抽样误差模块。此模块使用Taylor线性化方法估计调查估计值的方差，对于均值或比例的估计值。Jackknife重复复制方法用于更复杂统计量（如生育率和死亡率）的方差估计。

Jackknife重复复制方法从父样本的多次复制中推导出复杂率的估计值，并使用简单公式计算这些估计值的标准误差。每次复制考虑了估计值计算中除了一个集群之外的所有集群。因此，创建了伪独立的复制。在SADHS中，有966个非空集群。因此，创建了965次复制。

SADHS的抽样误差针对被认为是主要变量的选定变量进行计算。结果在最终报告的附录中呈现，针对整个国家、城市和农村地区、每个省份以及每个四个人口群体。对于每个变量，表格B.1中给出了统计量的类型（平均值、比例或率）和基数人口。

数据评估
---------------------------
非抽样误差是由于在数据收集和处理过程中犯的错误而产生的结果，例如未能找到和访谈正确的家庭、访谈员或受访者对问题的误解，以及数据录入错误。尽管在SADHS的实施过程中做出了许多努力来最大限度地减少此类错误，但非抽样误差是无法避免的，并且难以进行统计分析。