National Income Dynamics Study 2012, Wave 3 - South Africa

Abstract
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The National Income Dynamics Study (NIDS) is a face-to-face longitudinal survey of individuals living in South Africa as well as their households. The survey was designed to give effect to the dimensions of the well-being of South Africans, to be tracked over time. At the broadest level, these were:
Wealth creation in terms of income and expenditure dynamics and asset endowments;
Demographic dynamics as these relate to household composition and migration;
Social heritage, including education and employment dynamics, the impact of life events (including positive and negative shocks), social capital and intergenerational developments;
Access to cash transfers and social services

Wave 1 of the survey, conducted in 2008, collected the detailed information for the national sample.
Wave 2 of NIDS re-interviewed respondents interviewed in Wave 1, gathering information on developments in their lives since they were interviewed in 2008.
Wave 3 of the survey took place between April and December 2012 and re-interviewed respondents from Waves 1 and 2.

Completed and non-response interviews in the NIDS data:
The NIDS datasets contain both completed and non-response interviews (e.g. Refusals). It is recommended that researchers limit their research to completed interviews to avoid item non-response from non-response interviews. The completed interviews can be identified by making use of the w`x'_`y'_outcome variables, where `x' represents the wave and `y' represents the relevant data file/outcome type indicator. These outcome variables can be found in each of the following data files, Adult, Child, Proxy, HHQuestionnaire and Link File.
The only exception to this is Wave 1 where no outcome variable exists. This is because at a household level, all of the interviews are completed. However this does not apply at an individual level where non-response interviews can be identified by making use of the "Reason for refusal" variables, namely w1_a_refexpl or w1_c_refexpl in the Adult and Child data files respectively.

Geographic coverage
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The NIDS data is nationally representative. The survey began in 2008 with a nationally representative sample of over 28,000 individuals in 7,300 households across the country. The survey is repeated every two years with these same household members, who are called Continuing Sample Members (CSMs). The survey is designed to follow people who are CSMs, wherever they may be in SA at the time of interview. The NIDS data is therefore, by design, not representative provincially or at a lower level of geography (e.g. District Council).

Analysis unit
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The units of analysis in the survey are individuals and households.
The NIDS questionnaires attempted to gather information on all members of the household; including those that were resident and those that were non-resident at the time of the interview. Those that were resident provided the base sample of individuals who will remain in the NIDS sample over time. Information about non-resident members is essential in understanding the household and family support systems that individuals have around them at the time of the interview.

Universe
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The target population for NIDS was private households in all nine provinces of South Africa, and residents in workers' hostels, convents and monasteries. The frame excludes other collective living quarters, such as student hostels, old age homes, hospitals, prisons and military barracks.

Kind of data
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Sample survey data [ssd]

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

Data appraisal
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Questionnaire Section 3: Food expenditure and consumption data:
NIDS collected data on total food expenditure of the household. The questions used to collect food consumption data were:
E1.1 What was the total food expenditure of this household in the last 30 days? (variablename fdtot)
E1.2 Would you say the total food expenditure for this household in the last 30 days was (fdtot_brac1-6)
E1.3a Did you receive any foodstuffs as payment in the last 30 days? (fdrec)
E1.3b Did you produce/grow/gather any foodstuffs in the past 30 days? (fdprd)
E1.3c Did you consume any foodstuffs in the past 30 days out of your own shop stock? (fdcon)
In NIDS Wave 1 (2008) and Wave 2 (2010-2011) enumerators asked these questions and questions on detailed food expenditure and consumption. From Wave 3 (2012) onwards, if the total food expenditure data was deemed to be accurate based on computer checks, enumerators skipped past the detailed food consumption questions. Therefore, from Wave 3 detailed food consumption variables will not be included in the household data file. Data users are advised to read the questionnaire for more detail on the skip patterns in this section.

Questionnaire Section 7 Question S7: Private Security of Household:
The Interviewer Evaluation Section of the NIDS Household questionnaire (Section 7) has a question (S7) on the level/type of private security on the HH premises. This assessment is made by the interviewer. Data from the Interviewer Evaluation Section (Section 7) of the questionnaire was not released in Wave 1 (2008) and Wave 2 (2010-2011). From Wave 3 (2012) an anonymised version of the evaluation data has been made available in the NIDS public release.However, private security of HH data collected with question S7 was excluded and is not available in the NIDS public release data or secure data as it doesn't fall within the scope of NIDS respondent consent.

摘要
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国家收入动态研究（NIDS）是对居住在南非的个人及其家庭进行面对面纵向调查的研究。该调查旨在体现南非人民福祉的各个维度，并随时间追踪其变化。在最高层次上，这些维度包括：

收入与支出动态以及资产禀赋意义上的财富创造；
与家庭构成和移民相关的 demographics 动态；
包括教育与就业动态、生活事件（包括正面和负面冲击）的影响、社会资本以及代际发展在内的社会遗产；
以及现金转移和社会服务的获取。
调查的第一波（2008年）收集了全国样本的详细信息。
NIDS 的第二波调查重新采访了第一波调查中的受访者，收集了自2008年受访以来他们生活中的发展信息。
第三波调查于2012年4月至12月进行，重新采访了第一波和第二波的受访者。

NIDS 数据集中的完成访谈和非响应访谈：
NIDS 数据集包含完成访谈和非响应访谈（例如拒绝）。建议研究人员将研究限制在完成访谈上，以避免非响应访谈中的项目非响应。可以通过使用 w`x'_`y'_outcome 变量来识别完成访谈，其中 `x'` 代表波次，`y'` 代表相关的数据文件/结果类型指示符。这些结果变量可以在每个以下数据文件中找到，包括成人、儿童、代理、家庭问卷和链接文件。
唯一的例外是第一波，因为没有结果变量。这是因为在家庭层面上，所有访谈都是完成的。然而，这并不适用于个人层面，在个人层面上，可以通过使用“拒绝原因”变量来识别非响应访谈，例如成人数据文件中的 w1_a_refexpl 或儿童数据文件中的 w1_c_refexpl。

地理覆盖范围
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NIDS 数据在全国范围内具有代表性。调查始于2008年，在全国范围内对超过28,000名个人和7,300个家庭进行了抽样调查。调查每两年重复一次，调查同一家庭成员，这些成员被称为持续样本成员（CSMs）。调查旨在追踪CSMs，无论他们在访谈时的位置如何。因此，NIDS 数据在设计上不是按省份或更低地理级别（例如区议会）具有代表性。

分析单元
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调查的分析单元为个人和家庭。
NIDS 问卷试图收集关于家庭所有成员的信息；包括当时居住的和当时不在家的成员。居住的成员构成了将在一段时间内留在 NIDS 样本中的个人基础样本。了解非居住成员的信息对于理解访谈时的家庭和家庭成员支持系统至关重要。

总体
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NIDS 的目标总体为南非所有九个省的私人家庭，以及工人宿舍、修道院和修道院中的居民。框架排除了其他集体居住地，如学生宿舍、养老院、医院、监狱和军事营房。

数据类型
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样本调查数据 [ssd]

数据收集方式
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面对面 [f2f]

数据评估
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问卷第三部分：食品支出和消费数据：
NIDS 收集了关于家庭总食品支出的数据。用于收集食品消费数据的问题如下：

E1.1 上一个30天内，这个家庭的食品总支出是多少？（变量名 fdtot）
E1.2 你能否说上一个30天内这个家庭的食品总支出是（fdtot_brac1-6）
E1.3a 上一个30天内，你是否收到了任何作为报酬的食品？（fdrec）
E1.3b 过去30天内，你是否生产/种植/收集了任何食品？（fdprd）
E1.3c 过去30天内，你是否从自己的商店库存中消费了任何食品？（fdcon）
在NIDS第一波（2008年）和第二波（2010-2011年）中，调查员提出了这些问题以及关于详细食品支出和消费的问题。从第三波（2012年）开始，如果根据计算机检查，总食品支出数据被认为是准确的，调查员将跳过详细的食品消费问题。因此，从第三波开始，详细的食品消费变量将不包括在家庭数据文件中。建议数据用户阅读问卷以获取关于本节中跳转模式的更多详细信息。

问卷第七部分问题 S7：家庭私人安全：
NIDS 家庭问卷（第七部分）的访谈员评估部分有一个关于 HH 预设中私人安全水平/类型的问题（S7）。这种评估由访谈员进行。问卷的访谈员评估部分（第七部分）的数据在第一波（2008年）和第二波（2010-2011年）中没有发布。从第三波（2012年）开始，评估数据的匿名版本已作为 NIDS 公共发布的一部分提供。然而，使用问题 S7 收集的 HH 私人安全数据被排除在外，且在 NIDS 公共发布数据或安全数据中不可用，因为它不在 NIDS 受访者同意的范围内。