Namibia Household Income and Expenditure Survey - Namibia

Abstract
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The Namibia Household Income and Expenditure Survey (NHIES) 2015/2016 edition is the fourth of its kind to be executed in Namibia and the first to be carried out by the Namibia Statistics Agency (NSA) as per its first Strategic plan for the period of 2012/2013 to 2016/2017.

The NHIES is a household based survey, designed to collect data on income and expenditure patterns of households and the sole source of information on income and expenditure in the country. Therefore, institutions did not form part of this survey. Data from the NHIES is used to compute poverty indicators at household and individual levels. The survey also serves as a statistical framework for compiling the national basket items for the compilation of price indices used in the calculation of inflation. It also forms the basis for updating prices or rebasing of national accounts.

The implementation of NHIES 2015/16 was financed by the Government of the Republic of Namibia through the Ministry of Economic Planning sectoral budget. Technical support in the area of data processing, for example, the development of data entry and listing applications was provided by experts from the United States Census Bureau through funding by USAID. In addition, experts from the World Bank (WB) provided technical expertise for during data analysis and sampling.

The main objective of the Namibia Household Income and Expenditure Survey (NHIES 2015/2016) is to provide data to measure the levels of living of the population of Namibian, for example, using actual patterns of consumption and income, as well as a range of other socio-economic indicators. Statistical information from this survey will inform planning and policy making processes at national, regional and international levels in particular the implementation of Fifth National Development Plan, SADC agenda, AU Agenda 2063 and Sustainable Development Goals (SDGs). The NHIES was designed to provide policy makers with reliable, up to date and quality statistics at national, regional levels as well as rural urban disaggregated statistics for planning and decision making purposes.
A representative sample of 10368 households from 864 primary sampling units (PSUs) was selected for the survey. Data was collected over a twelve months period consisting of twenty two survey rounds.

After data processing, 10090 out of 10368 sampled households were used for analysis..

Geographic coverage
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The survey was national and covered representative samples from all 14 regions to
allow for regional, and urban and rural disaggregation at regional and national levels.

Due to financial constraints the survey was not able to collect data at levels lower than
regions, although it was desirable to do so.

The NHIES is a household based exercise which excludes institutional population such as those living in army barracks, prisons, hospitals, hostels and the
likes. However, private households in those institutions if selected were covered in the survey.

Analysis unit
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Unit of analysis in the survey is private households and individuals.

Universe
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The survey was national and covered representative samples from all 14 regions to
allow for regional, and urban and rural disaggregation at regional and national levels.

Due to financial constraints the survey was not able to collect data at levels lower than
regions, although it was desirable to do so.

The NHIES is a household based exercise which excludes institutional population such as those living in army barracks, prisons, hospitals, hostels and the
like. However, private households in those institutions if selected were covered in the survey.

Kind of data
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Sample survey data [ssd]

Sampling procedure
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The design of the NHIES 2015/2016 differs in comparison to previous NHIES undertakings. One such variation appears in the reduction of the number of households selected from the sampled primary sampling units (PSUs). This was done to increase the geographical coverage and by so doing increase the precision level of survey estimates.
16 Namibia Household Income and Expenditure Survey (NHIES) 2015/2016 Report

Survey Methodology
The number of households to be covered in each PSU have been reduced from 20 in previous NHIES to 12. This procedure increased the total number of PSUs sampled, from 500 in previous NHIES to 864 while keeping the overall sample households fixed. Similarly, the collection period of food transactions such as tobacco, beverage and food items in the households has also been reduced from 28 days in previous NHIES to 7 days.
This new survey methodology was adopted to increase the precision of indicators without significant impact on costs as well as to reduce the time interviewers spend in households thereby reducing the burden of response fatigue.

Target population and the survey population
The target population for the NHIES 2015/2016 was the non-institutional population residing in private households in Namibia. The Institutional population were out of scope for NHIES 2015/2016, however private households found within institutions were included in the target population. In addition, people who were homeless or those who usually reside in those private households, but were in hospital, prison and school hostels during the time of data collection were not eligible for NHIES 2015/2016. Table 2.1 below presents the list of institutional population, which were excluded, from the NHIES 2015/2016.

Sampling frame
The primary sampling frame used for this survey is a list of Primary sampling Units (PSUs) based on the 2011 Population and Housing Census Enumeration Areas (EAs). A PSU can be one EA, part of an EA or more than one EA. A secondary sampling frame for each of the selected PSUs was created for the purpose of selecting the sample households through a listing procedure.

The sampling design
The sample design for the survey was a stratified two-stage cluster sample, where the first stage units were geographical areas designated as the Primary Sampling Units (PSUs) and the second stage units were the households. The up-to-date list of households in the selected PSU were prepared during the listing stage of fieldwork, and 12 households were systematically selected in each PSUs.

The primary sample frame was stratified first by region followed by urban and rural areas within region. The Urban/rural strata were further stratified implicitly by constituencies.
The rural strata were also further stratified implicitly taking into consideration the proclaimed villages, settlements within the rural strata. Once this step was carried out the remaining PSUs in rural strata were implicitly stratified into communal and commercial farming areas. The PSUs within each of these areas were also geographically arranged.

The households in the secondary frame constitute a list of all households for each selected PSU were listed generally following a geographic order. Additional information was collected from the PSUs in the commercial farming areas for the purpose of carrying out further stratification before selecting sample households.

Sample selection
The first stage sample of PSUs was selected from the sampling frame using the probability proportional to size (PPS) sampling together with systematic sampling procedure. Once the PSUs were selected a listing operation was carried out to prepare a fresh list of households then 12 households were selected from the list of households (implicitly stratified) using a systematic sampling procedure. Selection of the sample households were carried out using a CSPro based sampling application.

Substitution of non-responding households
The survey was divided into four quarters and each quarter was further divided into survey rounds. During each survey round, some selected households did not respond to the survey as a result of non-contacts and/or refusals. If one household did not respond in a PSU this case was accepted as non-response. On the other hand if two or more non-responding households were encountered, then such households were replaced with households from a fresh selection in the same PSU. The replacement households were randomly selected using the CSPro based sampling application, designed to consider households with similar characteristics to the original selected households.

The NHIES sample distribution
The overall sample size was calculated to give reliable estimates of different characteristics at regional level as the lowest domain of estimation. The estimates of the characteristics for all other domains above the regional level will have better precision than the regions. The total sample size was 10368 households. A sample of 12 households were selected within each selected PSU from a freshly prepared list of households just before the interview. The total number of sampled PSUs was 864.

The survey needed to cover seasonal variations in different characteristics and therefore was carried out throughout the year. The survey year consists of four quarters, divided into survey rounds, which were 24 in total. Each survey round was made up of 15 days that a household was required to participate in the survey. The 864 PSUs were randomly allocated to the 24 survey rounds so that the sample selected for each round yield a representative sample at national level. Some adjustments were done when the allocated PSUs were drawn from the same stratum. Hence each survey round covered 36 PSUs that consisted of 432 households.

Sample Realization
The data collection process was followed by the verification of the number of households and PSUs received against the actual sample. This was then followed by structural editing process to ensure completeness of information and once this exercise was completed, the household file and person file was made available for weighting. The household file received had 10090 records, while the individual file had 41581 records, which were used for the weights calculation.

Mode of data collection
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Face-to-face interviews [f2f]

Research instrument
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Two Forms (questionnaires) were used to record information on consumption and income using a face-to-face interview method. Form I recorded demographic information and transactions of infrequent nature like purchases of durable goods as well as other information from other modules while Form II or daily record book (DRB) was used to capture information of daily transactions such as buying of bread, presents given to members of households and gifts given outside the household, etc. during the survey round. Households were shown how to record daily transactions. However, where there were no literate persons in the households, interviewers visited them on daily basis in order to help with daily DRB recordings.

Cleaning operations
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Data entry application was built with many consistency checks, skipping patterns and other validations such as maximum and minimum acceptance range per variable. Supervisors were given minimum variables to check on a day-to-day basis, especially for other - specify (notes) variables. As a result, data consistency checks, coding and validation was done at field level. This minimized the time spent on post data cleaning, validation and editing process.

Response rate
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After data processing, 10090 out of 10368 sampled households were successfully used for analysis, resulting in a 97.3 percent response rate which is highly satisfactory as exceeds the NSA target response rate of 80 percent for all data collection in the social statistics domain. The lowest response rate of 94.1% was observed in Khomas region.

Sampling error estimates
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The sampling error of a particular statistics is measured in terms of the standard error of that statistics which is the square root of the variance. The standard error is the standard deviation of the statistics which measures the variability in the estimates around the expected value. The standard error given in this report were estimated using the Taylor series Linearization method in Stata 12.1 program.

摘要
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纳米比亚 household income and expenditure survey (NHIES) 2015/2016 版本是该系列第四次在纳米比亚实施，也是纳米比亚统计局（NSA）根据其2012/2013至2016/2017年首个战略规划首次执行的调查。

NHIES是一项基于家庭的调查，旨在收集有关家庭收入和支出模式的资料，并成为该国收入和支出的唯一信息来源。因此，机构并未包含在本调查范围内。NHIES的数据用于计算家庭和个人层面的贫困指标。该调查还充当编制国家篮子项目的统计框架，用于编制计算通货膨胀率所使用的价格指数。它还构成了更新国家账户价格或重新定基的基础。

NHIES 2015/16的实施由纳米比亚共和国政府通过经济规划部预算资助。在数据处理领域的技术支持，例如数据录入和列表应用程序的开发，由美国人口普查局的专家提供，该支持由 USAID 资助。此外，世界银行（WB）的专家在数据分析抽样期间提供了技术专长。

纳米比亚 household income and expenditure survey (NHIES 2015/2016) 的主要目标是提供数据以衡量纳米比亚人口的生活水平，例如，使用实际的消费和收入模式，以及一系列其他社会经济指标。该调查的统计信息将特别为国家、地区和国际层面的规划和政策制定过程提供信息，特别是第五个国家发展计划、SADC议程、非洲联盟2063议程和可持续发展目标（SDGs）的实施。NHIES旨在为政策制定者提供可靠、最新和质量高的国家、地区统计数据，以及用于规划和决策的农村和城市分解统计数据。

在调查中，从864个一级抽样单位（PSU）中选择了10368个家庭的代表性样本。数据收集持续了十二个月，包括二十二轮调查。

在数据处理后，10368个抽样家庭中有10090个用于分析。

地理覆盖范围
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该调查是全国性的，涵盖了所有14个地区的代表性样本，以便在地区和全国层面上进行地区、城市和农村分解。

由于财务限制，调查未能收集到低于地区层面的数据，尽管有此愿望。

NHIES是一项基于家庭的调查，不包括军队营房、监狱、医院、宿舍等机构人口。然而，如果选中，这些机构中的私人家庭也包括在调查范围内。

分析单位
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调查的分析单位是私人家庭和个人。

总体
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该调查是全国性的，涵盖了所有14个地区的代表性样本，以便在地区和全国层面上进行地区、城市和农村分解。

由于财务限制，调查未能收集到低于地区层面的数据，尽管有此愿望。

NHIES是一项基于家庭的调查，不包括军队营房、监狱、医院、宿舍等机构人口。然而，如果选中，这些机构中的私人家庭也包括在调查范围内。

数据类型
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样本调查数据 [ssd]

抽样程序
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与之前的 NHIES 执行相比，NHIES 2015/2016 的设计有所不同。其中一个变化是减少了从抽样一级抽样单位（PSU）中选定的家庭数量。这样做是为了增加地理覆盖范围，并通过这种方式增加调查估计的精确度。

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