National Income Dynamics Study 2010-2011, Wave 2 - 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. In 2010/2011 Wave 2 of NIDS re-interviewed these people, gathering information on developments in their lives since they were interviewed first in 2008. As such, the comparison of Wave 1 and Wave 2 information provides a detailed picture of how South Africans have fared over two years of very difficult socio-economic circumstances.

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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Households and individuals

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]

Research instrument
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As in Wave 1 four types of questionnaires were administered in Wave 2:

Household questionnaire: One household questionnaire was completed per household by the oldest woman in the household or another person knowledgeable about household affairs and particularly household spending. Household questionnaires took approximately 45 minutes in non-agricultural households and 70 minutes in agricultural households to complete.
Individual Adult questionnaire: The Adult questionnaire was applied to all present Continuing Sample Members and other household member's resident in their households that are aged 15 years or over. This questionnaire took an average of 45 minutes per adult to complete.
Individual Proxy Questionnaire: Should an individual qualifying for an Adult questionnaire not be present then a Proxy Questionnaire (a much reduced Adult Questionnaire using third party referencing in the questioning) was taken on their behalf with a present resident adult. On average a Proxy questionnaire took 20 minutes. Proxy Questionnaires were also asked for CSMs who had moved out of scope (out of South Africa or to a non-accessible institution such as prison), except if the whole household moved out of scope, and could therefore not be tracked or interviewed directly.
Child questionnaire: This questionnaire collected information about all Continuing Sample Members and residents in their household younger than 15. Information about the child was gathered from the care-giver of the child. The questionnaire focused on the child's educational history, education, anthropometrics and access to grants. This questionnaire took an average of 20 minutes per child to complete.

Phase Two of Wave 2:
In June 2011 NIDS commissioned a Phase Two of Wave 2 as a Non-Response Follow-Up from Phase 1 of Wave 2. Household included in this subsample where those that refused and those that could not be located or tracked in Phase 1. Out of a total of 1064 households attempted, an additional 389 households were successfully interviewed in Phase Two.

Questionnaire Differences between W2 Phase 1 & W2 Phase2
There are two important methodological differences between Phase 1 and Phase 2:
1. Not all sections of the original Wave 2 questionnaires were asked. This reduced respondent burden and the time required for fieldworker training. Questions NOT asked in Phase 2 are indicated with the non-response code “-2”. Core modules such as household composition and income were still asked. Consult the Wave 2 Phase 2 questionnaires for more details of these differences.
2. Movers out of Phase 2 dwelling units were not tracked further. Address information was collected for this sub-sample and they will be tracked as part of the Wave 3 fieldwork exercise. These individuals are classified as “Not tracked” in the Wave 2 dataset.

摘要
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国家收入动态研究（NIDS）是对生活在南非的个体及其家庭进行面对面纵向调查的课题。该调查旨在对南非人民福祉的各个方面进行跟踪研究。在最为宏观的层面上，这些维度包括：

- 以收入和支出动态以及资产禀赋为表征的财富创造；
- 与家庭构成和人口迁移相关的 demographics 动态；
- 社会遗产，包括教育、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；
- 货币转移和社会服务的获取。

调查的第一波，于 2008 年进行，收集了全国样本的详细信息。在 2010/2011 年的第二波 NIDS 中，对这些个体进行了重新访谈，收集了自 2008 年首次访谈以来他们生活中的发展变化信息。因此，第一波和第二波信息的比较为南非人在两年极为困难的社会经济环境下的状况提供了一个详细的画面。

NIDS 数据集中已完成和非响应访谈：
NIDS 数据集包含已完成和非响应访谈（例如，拒绝）。建议研究人员将研究限定于已完成访谈，以避免来自非响应访谈的项非响应。可以通过利用 `w`x'_`y'_outcome` 变量来识别已完成访谈，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以下每个数据文件中找到，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，其中不存在结果变量。这是因为在家庭层面，所有访谈都是完成的。然而，这并不适用于个人层面，其中可以通过利用“拒绝原因”变量来识别非响应访谈，即在成人数据文件中的 `w1_a_refexpl` 或在儿童数据文件中的 `w1_c_refexpl`。

地理覆盖范围
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NIDS 数据具有全国代表性。调查始于 2008 年，覆盖全国 7,300 个家庭，样本量超过 28,000 人。调查每两年重复一次，针对这些相同的家庭成员，被称为持续样本成员（CSMs）。调查旨在追踪这些 CSMs，无论他们在访谈时的南非何地。因此，NIDS 数据按照设计不是在省级或更低地理层次（例如，地区议会）上具有代表性。

分析单元
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家庭和个人

总体
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NIDS 的目标总体是南非所有九个省份的私人家庭以及工人宿舍、修道院和修道院的居民。框架不包括其他集体居住地，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]

研究工具
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与第一波一样，第二波实施了四种类型的问卷：

- 家庭问卷：每户由家庭中年龄最大的女性或对家庭事务和特别是家庭支出有了解的其他人完成一份家庭问卷。在非农业家庭中，完成家庭问卷大约需要 45 分钟，在农业家庭中需要 70 分钟。
- 成人问卷：成人问卷适用于所有现存的持续样本成员以及居住在他们家庭中且年龄在 15 岁或以上的其他家庭成员。每位成人完成问卷的平均时间为 45 分钟。
- 代理问卷：如果符合成人问卷资格的个体不在场，则由一位在场居住的成人代表他们完成一份代理问卷（使用第三方参考的简化成人问卷）。平均而言，代理问卷需要 20 分钟。
- 儿童问卷：该问卷收集关于所有持续样本成员及其家庭中 15 岁以下居住者的信息。关于儿童的信息由儿童的监护人提供。问卷重点在于儿童的教育历史、教育、人体测量学和补助金获取情况。平均而言，每名儿童完成问卷需要 20 分钟。

第二波第二阶段：
2011 年 6 月，NIDS 对第二波第一阶段进行了第二阶段的非响应后续调查。包括拒绝和第一阶段中无法找到或追踪的家庭在内的子样本。在总共 1064 个家庭中，第二阶段成功访谈了额外的 389 个家庭。

W2 第一阶段与 W2 第二阶段问卷的差异：
在第一阶段和第二阶段之间存在两种重要的方法论差异：
1. 并非询问了原始第二波问卷的所有部分。这减少了受访者的负担和田野工作者培训所需的时间。未在第二阶段询问的问题以非响应代码“-2”表示。核心模块，如家庭构成和收入，仍然被询问。有关这些差异的更多详细信息，请参阅第二波第二阶段问卷。
2. 未对第二阶段住宅单元迁出者进行进一步追踪。为该子样本收集了地址信息，他们将在第三波实地调查中被追踪。这些个体在第二波数据集中被分类为“未追踪”。