Demographic and Health Survey 2000 - Namibia

Abstract
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The 2000 Namibia Demographic and Health Survey (NDHS) was implemented to assess the progress made in the health sector since the 1992 NDHS. It therefore focused on measuring achievements related to the same indicators as in 1992, but also included new aspects, e.g. HIV/AIDS. Furthermore, the 2000 NDHS was designed to obtain reliable data for all 13 administrative regions, which had not been established at the time of the 1992 NDHS. In addition, data for the four MOHSS Regional Directorates are included, which provide comparison to the 1992 NDHS results at the sub-national level.

A nationally representative sample of 6,755 women age 15-49 and a sub-sample of about 2,954 men age 15-59 were interviewed in the 2000 NDHS. Twenty mobile teams conducted the interviews from late September to mid-December 2000.

The primary objective of the 2000 NDHS was to provide up-to-date information on fertility and mortality, family planning, fertility preferences, maternal and child health, and knowledge and behaviour regarding HIV/AIDS. The 2000 NDHS was patterned after the 1992 NDHS so as to maximise the ability to measure trends on similar indicators between 1992 and 2000. The ultimate intent is to use this information to evaluate existing programmes and design new strategies in order to ensure delivery of health and social welfare services to the population in a cost effective and efficient manner.

MAIN RESULTS

- Household Characteristics : As part of the 2000 NDHS, households were assessed as to the availability of various amenities. The survey found that 79 percent of households have access to safe drinking water, compared to only 68 percent in 1992.Nationally, 45 percent of households have sanitary means of excreta disposal, compared to 40 percent in 1992. There are large disparities by residence, with 85 percent of households in urban areas having sanitary toilets, compared to only 19 percent of rural households. Overall, some 63 percent of households consume adequately iodised salt. The disparity between urban and rural areas is small at 68 percent and 60 percent, respectively.

- Fertility : The total fertility rate (TFR) for the three-year period before the survey is 4.2 births per woman. This represents a sharp decline from 5.4 births per woman for the 3-year period prior to 1992, a net reduction of 1.2 children or a 22 percent decline over the past eight years.

- Family planning : Some knowledge of family planning is nearly universal among Namibian women, 97 percent of whom have heard of at least one method. Knowledge of methods is only slightly higher among married women than all women.

- Fertility Preferences : Overall, close to half (48 percent) of all women age 15-49 either do not want any more children or have already been sterilised. Forty-five percent of women would like to have a child in the future; however, half of these women (22 percent) would like to wait two or more years before having another child.

- Maternal Health : Survey results show that the vast majority of pregnant women in Namibia (93 percent) receive antenatal care. More than 9 in 10 women receive antenatal care from a medical professional (91 percent), mostly from nurses and midwives (78 percent). Doctors provide 13 percent of antenatal care services, while traditional birth attendants provide only 2 percent of antenatal care.

- Child Health : According to the health passport and mothers' reports, 65 percent of children 12-23 month have received all the recommended vaccinations, and only 5 percent have not received any vaccinations. When compared to the 1992 NDHS, the percentage of children aged 12-23 months who had received all vaccinations has improved, from 58 percent in 1992 to 65 percent in 2000.

- HIV/AIDS : Awareness of AIDS is almost universal in Namibia, with 98 percent of women and over 99 percent of men saying they had heard of AIDS. It is very encouraging to note that large majorities of both women (81 percent) and men (87 percent) spontaneously mention condoms as a means of avoiding HIV.

In conclusion, the 2000 NDHS provides a valuable source of data on a wide variety of indicators, which permit the assessment of progress achieved over the past 8 years. In general, considerable improvements have occurred in the health sector. However, many challenges remain to further improve the health of the Namibian nation.

Geographic coverage
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The 2000 NDHS sample was designed to produce reliable estimates of most of the major survey variables for the country as whole; for urban and rural areas separately; and for each of the 13 regions.

Analysis unit
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- Household
- Women age 15-49
- Men age 15-59
- Children under five

Universe
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The population covered by the 2000 NDHS is defined as the universe of all women age 15­-49 in Namibia and all men age 15-54 living in the household.

Kind of data
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Sample survey data

Sampling procedure
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The 2000 NDHS sample was designed to produce reliable estimates of most of the major survey variables for the country as whole; for urban and rural areas separately; and for each of the 13 regions. The design called for a nationally representative probability sample of 6,500 women age 15-49 and a subsample of about 3,000 men age 15-59.

The 2000 NDHS sample was largely based on the Central Bureau of Statistics' master sample, drawn from the list of enumeration areas (EAs) created for the 1991 census. In 1997, new EAs were demarcated in Walvis Bay, which was not part of Namibia at the time of the 1991 census. The new EAs were incorporated into the 1991 census frame and the number of primary sampling units (PSUs) in the master sample was increased. A PSU corresponds to an entire EA or a group of EAs.

Due to considerable rural-urban migration, extensive peripheral development and intensive development of previously rural areas has taken place since 1991, particularly in Windhoek. At the time of the 2000 NDHS sample design, new EAs were being demarcated for the upcoming population census. A list of the new EAs in the urban areas of Caprivi, Hardap, Kunene, Omaheke, Oshana, and Otjozondjupa Regions was made available for the sample selection. Finally, in Khomas Region, a quick count of dwellings both in the old EAs within Windhoek and in the newly demarcated EAs in the informal settlement zones on the outskirts of Windhoek was implemented in order to get an up-to-date measure of size for the capital city.

The sampling frame for the 2000 NDHS was obtained by supplementing the master sample with the list of the new EAs in urban areas in selected regions and the updated EAs in Khomas Region. It should also be noted that the urban-rural classification of EAs was changed in the master sample so as to reflect the recent proclamation of municipalities, towns and villages. Some of the EAs were also shifted from one region to another following changes in regional boundaries.

The 2000 NDHS sample was selected in two stages. In the first stage, 260 PSUs (106 urban and 154 rural) were selected with probability proportional to the number of households within the PSU. Each selected PSU was divided into segments, one of which was retained in the sample. All households residing in the selected segment were included in the sample and all women age 15-49 listed in these households were eligible for individual interview. In one-half of the households, all men age 15-59 were also eligible.

Mode of data collection
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Face-to-face

Research instrument
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The 2000 NDHS involved three questionnaires: a) a household questionnaire, b) a questionnaire for individual women 15-49, and c) a questionnaire for individual men 15-59. These instruments were based on the model questionnaires developed for the international DHS program, as well as on the questionnaires used in the 1992 NDHS.

The questionnaires were developed in English and translated into six local languages-Afrikaans, Damara/Nama, Herero, Kwangali, Lozi, and Oshiwambo. People other than the initial translators did back translations into English with the goal of verifying the accuracy of the translations.

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/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 eligible for individual interview and children under five who were to be weighed and measured. In addition, information was collected about the dwelling itself, such as the source of water, type of toilet facilities, materials used to construct the house, ownership of various consumer goods, use of iodised salt, and household expenditures on health care.

b) The Woman's Questionnaire was used to collect information from all women aged 15-49 and covered the following topics:
- Background characteristics (age, education, religion, etc.);
- Reproductive history;
- Knowledge and use of contraceptive methods;
- Antenatal, delivery, and postnatal care (including tetanus toxoid testing);
- Breastfeeding and weaning practices;
- Child health and immunisation;
- Marriage and recent sexual activity;
- Fertility preferences;
- Knowledge of HIV/AIDS (condom use, number of partners, etc.);
- Maternal mortality;
- Husband's background and respondent's work.

c) In every second household, in addition to the women, all men age 15-59 were eligible to be interviewed with the Man's Questionnaire, which covered:
- Background characteristics (age, education, religion, etc.);
- Knowledge and use of contraceptive methods;
- Marriage and recent sexual activity;
- Fertility preferences;
- Knowledge of HIV/AIDS (condom use, number of partners, etc.);
- Respondent's work.

The survey instruments were pretested in three areas (one urban and two rural) outside the segments drawn in the sample. About 200 women and 200 men were interviewed in the pretest, the results of which were used to modify the survey instruments as necessary.

Cleaning operations
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After field editing and correction in the field, all completed questionnaires were sent to the Multisdisciplinary Research Centre at the University of Namibia in Windhoek for logging in and supplementary editing prior to data entry. The processing operation consisted of office editing, coding of open-ended questions, initial data entry and subsequent re-entry (verification) of all questionnaires to ensure correct capturing of data, and editing of inconsistencies found by the computer programs. ORC Macro staff provided assistance in developing the programs for data entry, training of data processing personnel and editing in the Integrated System for Survey Analysis (ISSA) computer package. A team of two supervisors and 16 data entry operators, working in two six-hour shifts, completed data processing activities in February 2001.

Response rate
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In all, 6,849 households were selected for the 2000 NDHS, of which 6,594 were reported occupied at the time of the interview. The primary reasons for the difference were households that were away for an extended period of time and dwellings that were vacant.

Interviews were completed in 6,392 households or 97 percent of the occupied households. In the interviewed households, 7,308 women were identified as eligible for the individual interview, of which 6,755 (92 percent) were successfully interviewed. Of the 3,551 men identified as eligible in every second household, 2,954 (83 percent) were interviewed. The principal reason for non-responses among eligible women and men was the failure to find them at home despite repeated visits to the household.

Sampling error estimates
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Sampling errors, on the other hand, can be evaluated statistically. The sample of respondents selected in the 2000 NDHS 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 2000 NDHS 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 2000 NDHS 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 2000 NDHS, there were 260 non-empty clusters. Hence, 260 replications were created.

In addition to the standard error, ISSA 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. ISSA also computes the relative error and confidence limits for the estimates.

Sampling errors for the NDHS are calculated for selected variables considered to be of primary interest. The results are presented in an appendix of the Final Report for the country as a whole, urban and rural area separately, and for each region and group of regions. 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.21 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, as there is no known unweighted value for woman-years of exposure to child-bearing. Sampling errors for fertility and childhood mortality rates are presented only for the whole country, urban and rural areas, and for groups of regions (Northwest, Northeast, Central and South).

The confidence interval (e.g., as calculated for Children ever born to women aged 15-49) can be interpreted as follows: the overall average from the national sample is 2.148 and its standard error is 0.037. Therefore, to obtain the 95 percent confidence limits, one adds and subtracts twice the standard error to the sample estimate, i.e., 2.148 ± 2 × 0.037. 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 2.074 and 2.221.

Sampling errors are analysed for the national woman 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 0.4 percent and 76.5 percent with an average of 8.6 percent; the highest relative standard errors are for estimates of very low values (e.g., Women currently using withdrawal). If estimates of very low values (less than 10 percent) were removed, then the average would drop to 3.2 percent. So in general, the relative standard errors 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, 3.5 percent. However, for the mortality rates, the average relative standard error is much higher, 12.7 percent.

There are differentials in the relative standard error for the estimates of sub-populations. For example, for the variable Currently married, the relative standard errors as a percent of the estimated mean for the whole country, and for Ohangwena Region and the Northwestern Directorate are 2.9 percent, 15.1 percent, and 6 percent, respectively.

For the total sample, the value of the design effect (DEFT), averaged over all variables, is 1.57 which means that, due to multi-stage clustering of the sample, the average standard error is increased by a factor of 1.57 over that in an equivalent simple random sample.

Data appraisal
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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 2000 Namibia Demographic and Health Survey to minimise this type of error, nonsampling errors are impossible to avoid and difficult to evaluate statistically.

摘要
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2000年纳米比亚人口与健康调查（NDHS）旨在评估自1992年NDHS以来卫生领域取得的进展。因此，它侧重于测量与1992年相同指标相关的成就，同时还包括新的方面，例如HIV/AIDS。此外，2000年NDHS旨在获取所有13个行政区域的可靠数据，这些区域在1992年NDHS时尚未建立。此外，还包括了四个MOHSS区域总监的数据，这些数据在次国家层面上与1992年NDHS的结果进行了比较。

在2000年NDHS中，对6,755名15-49岁女性和约2,954名15-59岁男性的全国代表性样本进行了访谈。20个流动团队从2000年9月下旬至12月中旬进行了访谈。

2000年NDHS的主要目标是提供有关生育和死亡率、计划生育、生育意愿、母亲和儿童健康以及关于HIV/AIDS的知识和行为的最新信息。2000年NDHS的设计灵感来源于1992年NDHS，以便最大限度地提高测量1992年和2000年之间类似指标趋势的能力。最终目的是利用这些信息来评估现有项目并设计新战略，以确保以成本效益和高效的方式向人口提供卫生和社会福利服务。

主要结果
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- 家庭特征：作为2000年NDHS的一部分，家庭被评估了各种便利设施的可用性。调查发现，79％的家庭有安全饮用水，而1992年仅为68％。在全国范围内，45％的家庭有卫生的排泄物处理方式，而1992年为40％。在居住地方面存在巨大差异，城市地区85％的家庭有卫生厕所，而农村家庭仅为19％。总体而言，大约63％的家庭消费足够的碘化盐。城市和农村地区之间的差异很小，分别为68％和60％。

- 生育率：调查前三年总生育率（TFR）为每名女性4.2个出生。这比1992年前三年每名女性5.4个出生的生育率有显著下降，净减少1.2个孩子或在过去八年中下降22％。

- 计划生育：几乎所有的纳米比亚女性都对计划生育有所了解，97％的女性至少听说过一种方法。已婚女性对方法的了解略高于所有女性。

- 生育意愿：总体而言，近一半（48％）的15-49岁女性要么不想要更多孩子，要么已经绝育。45％的女性希望在将来有孩子；然而，其中一半女性（22％）希望再过两年或更长时间才要另一个孩子。

- 母亲健康：调查结果显示，纳米比亚绝大多数孕妇（93％）接受了产前护理。超过10名女性中有9名接受了医疗专业人员的产前护理（91％），其中主要是护士和助产士（78％）。医生提供了13％的产前护理服务，而传统接生员只提供了2％的产前护理。

- 儿童健康：根据健康护照和母亲的报告，65％的12-23个月大的儿童接受了所有推荐的疫苗接种，只有5％没有接受任何疫苗接种。与1992年NDHS相比，12-23个月大的儿童接受所有疫苗接种的比例有所提高，从1992年的58％提高到2000年的65％。

- HIV/AIDS：对艾滋病的认识在纳米比亚几乎是普遍的，98％的女性和超过99％的男性表示他们听说过艾滋病。值得注意的是，女性（81％）和男性（87％）都自发地提到避孕套作为避免HIV的一种手段。

结论：2000年NDHS提供了关于各种指标的宝贵数据来源，这些数据允许评估过去8年取得的进展。总的来说，卫生领域取得了相当大的进步。然而，仍有许多挑战需要进一步改善纳米比亚国民的健康。

地理覆盖范围
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2000年NDHS样本的设计旨在为整个国家、城市和农村地区以及每个13个地区的大多数主要调查变量产生可靠的估计。

分析单元
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- 家庭
- 15-49岁女性
- 15-59岁男性
- 5岁以下儿童

总体
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2000年NDHS涵盖的人口是纳米比亚所有15-49岁女性和所有15-54岁居住在户内的男性。

数据类型
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样本调查数据

抽样程序
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2000年NDHS样本的设计旨在为整个国家、城市和农村地区以及每个13个地区的大多数主要调查变量产生可靠的估计。

数据收集方式
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面对面

研究工具
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2000年NDHS涉及三个问卷：a）家庭问卷，b）15-49岁女性问卷，c）15-59岁男性问卷。这些工具基于为国际DHS项目开发的模型问卷，以及1992年NDHS中使用的问卷。

问卷是用英语开发的，并翻译成六种当地语言——阿非利堪斯语、达马拉/纳马语、赫雷罗语、宽加利语、洛齐语和希瓦语。除了最初的翻译者外，其他人将问卷回译成英语，目的是验证翻译的准确性。

a）家庭问卷用于列出所选家庭的全部常住和临时成员。收集了有关所列每个人特征的一些基本信息，包括他们的年龄、性别、教育和与户主的亲属关系。家庭问卷的主要目的是确定有资格进行个别访谈的女性和男性以及要称重和测量的5岁以下儿童。此外，还收集有关住宅本身的信息，例如水的来源、厕所设施的类型、建造房屋使用的材料、各种消费品的所有权、碘化盐的使用以及家庭在卫生保健上的支出。

b）女性问卷用于收集所有15-49岁女性的信息，包括以下主题：
- 背景（年龄、教育、宗教等）；
- 生殖史；
- 对避孕方法的了解和使用；
- 产前、分娩和产后护理（包括破伤风毒素测试）；
- 哺乳和断奶实践；
- 儿童健康和免疫；
- 婚姻和最近的活动；
- 生育意愿；
- 对HIV/AIDS的了解（避孕套使用、伴侣数量等）；
- 母亲死亡率；
- 丈夫的背景和受访者的工作。

c）在每两个家庭中，除了女性外，所有15-59岁的男性也有资格接受男性问卷的访谈，该问卷涵盖：
- 背景（年龄、教育、宗教等）；
- 对避孕方法的了解和使用；
- 婚姻和最近的活动；
- 生育意愿；
- 对HIV/AIDS的了解（避孕套使用、伴侣数量等）；
- 受访者的工作。

调查工具在样本外抽取的三个地区（一个城市和两个农村）进行了预测试，大约有200名女性和200名男性接受了访谈，其结果用于根据需要对调查工具进行修改。

数据清理操作
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在实地编辑和纠正后，所有完成的问卷都发送到温得和克大学的多学科研究中心进行登记和补充编辑，以便在数据录入之前。处理操作包括办公室编辑、开放式问题的编码、所有问卷的初始数据录入和随后的重新录入（验证），以确保正确捕获数据，以及编辑计算机程序发现的矛盾。ORC Macro工作人员在开发数据录入程序、培训数据处理人员和ISSA计算机包中的编辑方面提供了协助。一个由两名监督员和16名数据录入员组成的团队，分两个六小时班次，于2001年2月完成了数据处理活动。

响应率
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总共选定了6,849个家庭进行2000年NDHS，其中6,594个家庭在访谈时被报告为有人居住。差异的主要原因是有较长时间不在家的家庭和空置的住宅。

在访谈的家庭中，确定了7,308名有资格进行个别访谈的女性，其中6,755名（92％）被成功访谈。在每两个家庭中，有3,551名男性有资格进行访谈，其中2,954名（83％）被访谈。有资格的女性和男性未能响应的主要原因是尽管反复访问家庭，但未能找到他们。

抽样误差估计
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另一方面，抽样误差可以通过统计方法进行评估。2000年NDHS中选定的受访者样本只是从同一人口中选出的许多可能样本之一，使用相同的设计和预期规模。每个这些样本都会产生与实际选定样本的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一种措施。虽然变异的程度无法确切知道，但它可以从调查结果中估计。

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，其中可以合理地假设总体真实值将落在其中。例如，对于从样本调查中计算出的任何给定统计量，该统计量的值将在95％的所有可能样本的相同大小和设计中加减两倍标准误差的范围内。

如果受访者样本被选为简单随机样本，则可以使用简单的公式来计算抽样误差。但是，2000年NDHS样本是分层设计的产物，因此有必要使用更复杂的公式。用于计算2000年NDHS抽样误差的计算机软件是ISSA抽样误差模块。该模块使用泰勒线性化方法进行方差估计，以估计调查估计值（平均值或比例）。对于更复杂的统计量，如生育率和死亡率，使用重复复制方法进行方差估计。

重复复制方法从多个重复的父样本中得出复杂率的估计值，并使用简单的公式计算这些估计值的标准误差。每个重复在估计的计算中考虑了除了一个聚类以外的所有聚类。因此，创建了伪独立的重复。在2000年NDHS中，有260个非空聚类。因此，创建了260个重复。

除了标准误差外，ISSA还为每个估计值计算设计效应（DEFT），该效应定义为使用给定样本设计计算的标准误差与使用简单随机样本将产生的结果的标准误差之比。DEFT值为1.0表示样本设计与简单随机样本一样有效，而值大于1.0表示由于使用更复杂且统计效率较低的样本设计而增加的抽样误差。

ISSA还计算估计值的相对误差和置信界限。

NDHS的抽样误差针对被认为具有首要意义的选定变量进行计算。结果在最终报告的附录中按国家整体、城市和农村地区分别以及每个地区和地区组进行了展示。对于每个变量，Table B.1中的最终报告中给出了统计量类型（平均值、比例或比率）和基人口。

抽样误差分析针对全国女性样本和两个独立的估计组：（1）平均值和比例，以及（2）复杂的统计数据。平均值和比例的相对标准误差（SE/R）介于0.4％和76.5％之间，平均为8.6％；最高的相对标准误差是针对非常低值的估计（例如，当前使用撤退的女性）。如果删除非常低值的估计（小于10％），则平均值将降至3.2％。因此，总的来说，大多数估计的相对标准误差很小，除了非常小的比例的估计。

对于总样本，所有变量的设计效应（DEFT）的平均值是1.57，这意味着由于样本的分层聚类，平均标准误差比等效简单随机样本增加了1.57倍。

数据评估
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非抽样误差是由于在实施数据收集和数据处理过程中出现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。尽管在实施2000年纳米比亚人口与健康调查期间做出了大量努力来最小化此类错误，但非抽样误差是不可避免的，并且难以进行统计分析。