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）是对居住在南非的个人及其家庭进行的面对面纵向调查。该调查旨在体现南非人民福祉的各个维度，并随着时间的推移进行追踪。在最广泛的层面上，这些维度包括：
1. 以收入和支出动态以及资产禀赋为标志的财富创造；
2. 与家庭构成和移民相关的户籍动态；
3. 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；
4. 货币转移和社会服务获取。
调查的第一波（2008年进行）收集了全国样本的详细信息。2010/2011年的第二波NIDS重新采访了这些人，收集了他们自2008年首次采访以来的生活发展信息。因此，第一波和第二波信息之间的比较提供了南非人在极为困难的两年社会经济环境下的详细情况。
NIDS数据中的完成和未回应访谈：
NIDS数据集包含完成和未回应的访谈（例如拒绝）。建议研究人员将研究限制在完成的访谈中，以避免未回应访谈中的项目非回应。可以通过使用w`x'_`y'_outcome变量来识别完成的访谈，其中`x'`代表波次，`y'`代表相关的数据文件/结果类型指标。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。这是因为从家庭层面来看，所有访谈都是完成的。然而，这并不适用于个人层面，在个人数据文件中可以通过使用“拒绝原因”变量（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）来识别未回应的访谈。
地理覆盖范围
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NIDS数据是全国代表性的。调查始于2008年，全国代表性样本超过28,000人，分布在7,300个家庭中。调查每两年重复一次，调查这些相同的家庭成员，他们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数据按设计不是按省份或更低地理层次（例如区议会）代表性的。
分析单位
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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。框架排除了其他集体居住区，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，在第二波中实施了四种类型的问卷：
家庭问卷：每个家庭由家庭中最年长的女性或对家庭事务特别是家庭支出有了解的其他人完成一份家庭问卷。非农业家庭完成家庭问卷大约需要45分钟，而农业家庭需要70分钟。
成人问卷：成人问卷适用于所有在场的持续样本成员以及居住在家庭中且年龄在15岁或以上的其他家庭成员。每个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人不在场，则由在场居住的成人代表进行代理问卷（使用第三方参考的简化的成人问卷）。平均代理问卷需要20分钟。对于已移出调查范围（出南非或到监狱等不可访问的机构）的CSMs，也会进行代理问卷，除非整个家庭移出调查范围，因此无法直接追踪或访谈。
儿童问卷：此问卷收集了所有持续样本成员及其家庭中年龄低于15岁的居民的信息。从孩子的监护人那里收集关于孩子的信息。问卷侧重于孩子的教育历史、教育、人体测量学和补助金获取。平均每个孩子完成问卷的时间为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一项非回应后续调查的第二阶段。包括拒绝和在第一阶段无法找到或追踪的家庭在内的子样本家庭。在总共1064个家庭中，第二阶段成功访谈了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个重要的方法学差异：
1. 没有询问原始第二波问卷的所有部分。这减少了受访者的负担和现场工作人员培训所需的时间。未在第二阶段询问的问题用非回应代码“-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的问卷。
2. 未进一步追踪第二阶段住宅单位中的移动者。为此子样本收集了地址信息，他们将在第三波实地调查中作为一部分进行追踪。这些个人在第二波数据集中被归类为“未追踪”。