National Income Dynamics Study 2012, Wave 3 Secure Data
Wave 3 Secure Data
Household Survey [hh]
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.
Kind of Data
Sample survey data [ssd]
Unit of Analysis
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.
v2.1: Edited, anonymised dataset for public distribution.
Version 1 of the National Income Dynamics Study wave 3 2012 public release dataset was received on 22 August 2013
CHANGES IN NIDS WAVE 3 2012 DATA FROM VERSION V1.0 TO VERSION V1.1
Admin data has been created for the first time for the Wave 3 data. As is the now the case in Wave 1 and 2 it is part of the regular wave specific pack. We hope that this convenience will enrich users' experience of developing research from this ever growing resource. The publically available data matches the names of schools as collected by NIDS to Department of Basic Education's Ordinary School's Master List. Only a limited number of variables are made publically available to protect the identities of NIDS respondents. A secure data facility is provided where researchers can match their own data sources based on EMIS numbers to the matched schools. See <http://www.nids.uct.ac.za/nids-data/secure-data> for further details.
In the last release, the best estimate for agriculture income w3_hhagric was calculated using two variables from the Adult questionnaire which are w3_a_empsll_v and w3_a_empconprod_v. In this release, income from agriculture activities is calculated using variables from the HHQuestionnaire file. The process used in the calculation for agriculture income in wave 3 is now similar to the process used in wave 1. See program library files on <http://www.nids.uct.ac.za/documents/program-library/151-wave-3-income-dofiles> for details on how agriculture income was calculated.
The variable w3_a_wncom which was incorrectly named in the Adult file in the last release has been renamed back to w3_a_owncom.
Birth History Section
In the Adult file there a few individual males who were listed as having given birth in variable w3_a_bhbrth. This error has now been rectified as it is impossible for males to give birth.
Non-Residents in the Link File
There were 53 records where individuals who were non-resident in Wave 1 were assigned a Wave 1 household identifier (w1_hhid) in the Wave 3 Link File. This has been corrected to ensure that no non-resident members have household identifier in the Link File in the waves that they are non-resident.
Through interaction with our users it was brought to our attention that the svyset command in STATA was retaining settings. We have subsequently removed these settings from all data sets.
CHANGES IN W3 FROM V1.1 TO V1.2
NIDS datasets have been reweighted to take into account the Census 2011 geographic data. Both the household level, as well as the individual level panel weights has been adjusted.
Previous geographic variables have been given the suffix ‘2001’ to distinguish them from the new geographic variables. The following variables were affected:
Old Variable Name New Variable Name
*Secure dataset variables
Census 2011 Geographic Variables have been brought into the NIDS dataset. The new variables are:
New Variable Name w3_gc_prov2011 w3_gc_dc2011 w3_gc_mdbdc2011 w3_hhgeo2011 w3_gc_eatype2011* w3_gc_ea2011* w3_gc_mp2011* w3_mapped_prov2011* w3_mapped_dc2011* w3_mapped_mdbdc2011* w3_mapped_mp2011* w3_mapped_geo2011* w3_mapped_ea2011* w3_mapped_eatype2011
*Secure dataset variables
More detail about this change can be found in the document detailing the Inclusion of Census 2011 data in NIDS.
Household Questionnaire for NIDS Wave 3 2012
The final version of the household questionnaire issued with the NIDS Wave 3 2012 Public Use Files had the codes for DECEASED and ABSENT in questions b18, b19 and b20 transposed from the original questionnaire used in data collection. This has been corrected in version 1.1 of this questionnaire (W3_hh_final-v1.1)
This version of the dataset includes a syntax file to correct two variables in NIDS Wave 3 2012 Adult, Child and Proxy data files. These variables were incorrectly coded for instances where the response should be '10: Out of the Country'. The variables are:
Province Respondent Born In (Question B11_3 (w3_a_brnprov), B7_3 (w3_c_brnprov), and B9_3 (w3_p_brnprov), in the Wave 3 Adult, Child and Proxy questionnaires respectively)
Province Before Current Location (Question B16_3 (w3_a_lvbfprov), B11_3 (w3_c_lvbfprov), and B14_3 (w3_p_lvbfprov), in the Wave 3 Adult, Child and Proxy questionnaires respectively)
The syntax file to correct this error was made available on 20141211. The file can also be donwloaded from http://uct.us4.list-manage.com/track/click?u=bd0f7609ff50e160e9ce007be&id=d7c44a1b8f&e=38fbde11d4
CHANGES IN W3 FROM VERSION 1.2 TO VERSION 1.3
This change relates to the following variables in the Wave 3 NIDS Adult data file.
· w3_a_emssect - E34.1 (Self-employment sector code),
· w3_a_emsothsect - E36.1 (Other self-employment sector code) and
· w3_a_emcprod_c - E49.1 (Casual employment sector codes
In all three cases the variables were inconsistently coded for the sectors: In previous waves the codes matched for the sectors highlighted below. Version 1.2 of Wave 3 had non-matching codes. These have been changed in version 1.3 to match codes for sectors by employment type, as in previous waves.
In addition to the above, the variable name w3_a_emcprod_c was incorrectly assigned to E49.1. The correct variable name is w3_a_emcsect.
This change relates to the following variables in the Wave 3 NIDS Adult, Child and Proxy datasets:
· Province Respondent Born In (Question B11_3 (w3_a_brnprov), B7_3 (w3_c_brnprov), and B9_3 (w3_p_brnprov), in the Wave 3 Adult, Child and Proxy questionnaires respectively)
· Province Before Current Location (Question B16_3 (w3_a_lvbfprov), B11_3 (w3_c_lvbfprov), and B14_3 (w3_p_lvbfprov), in the Wave 3 Adult, Child and Proxy questionnaires respectively)
In both cases the variables were incorrectly coded for instances where the response should be '10: Out of the Country'. This has now been corrected.
CHANGES IN W3 FROM VERSION 1.3 TO VERSION 2
New Variables/Info in version 3
In the Adult, Child and Proxy questionnaires NIDS gathers information regarding all the locations in which respondents have lived (Questions b10 - b16 in the adult questionnaire). These questions are collectively known as migration questions. In previous releases this data has only been coded using 2001 Census data to district municipality level (DC). In the latest release the data has been coded to both the 2001 and 2011 Census data, and with both versions of the district municipality codes. New variables for migration have the suffix dc_2001 and dc_2011 for descriptions coded to the 2001 and 2011 Census data respectively.
Birth History Section
NIDS embarked on an exercise to identify and match all the children across Wave 1 - Wave 4 on Birth History (BH). In cleaning this section, NIDS made calls to confirm the number of children the mother had given birth to. Therefore there were a lot of changes to this section because some children were either added or dropped in the mother's birth history. An additional gain from this exercise is that each child in the BH section now has a PID to identify them.
Police District data
Police district data has now been included as part of the Admin data file. Variables include distance to the nearest police station, and distance to the police station in the district in which the household is located. Only categorical distances have been included in the public release version of the data. Actual distances can be found in the secure (restricted access) version of the data.
An exercise to reduce inconsistences in the parental information was carried out for all individuals across all waves. Cases with problems were identified by comparing parental information across waves. In cases where the information varied across waves, calls were made to verify this information. Information obtained from the calls was used to correct the inconsistent parental data. Where respondents could not be contacted, the data remain unchanged.
The variable w3_pweightw2w3 was dropped from the indderived file. This was done for two reasons.
1. The number of weights to be calculated across waves increases exponentially with each wave. Researchers wishing to use the variablevcan use the method described in the Panel User Guide to calculate the weights.
2. The interpretation of this type of weight is very complex.
A list of all variables renamed in the new versions of the datasets can be found in the document "nids-w3-2012-changes" included in the dataset.
CHANGES IN VERSION 2.1
Version 2.1 had changes to the weights variables, w3_pweight in the indderived data file and the w3_wgt in the hhderived data file. Changes to these variables were necessary because:
1.Panel weights were missing for some babies born to CSM mothers after Wave 1 (2008)
2. The weight was missing for one (now adult) respondent
CHANGES IN VERSION 3.0.0
Version 3.0.0 of NIDS wave 3 includes changes to the number of individuals and households in each data file, largely driven by previously incorrect classification of TSM/CSM status, duplicate interviews and additional baby CSMs not captured in a previous version of this wave. Version 3.0.0 also contains new and renamed variables, and there are changes to the survey weights. For details on these changes please see the document Wave 3 Changes between V2.1 and V3.0.0 which is provided with the data.
Data on the following topics was collected during the survey:
HOUSEHOLD: Household characteristics, household roster, mortality history, living standards, expenditure, consumption, negative events, positive events, agriculture
ADULTS: Demographics, education, labour market participation, income, health, well-being, numeracy, anthropometric data
CHILDREN: Education, health, family support, grants, anthropometric data, numeracy.
The Secure (Restricted access) data files contain confidential variables that are not released in the publicly available data. The secure variables include the primary sampling unit (PSU), date of birth day, and full geo-codes. Employment codes are provided up to the four digit level, and a code-list for these is available with the data. A complete list of variables available in the restricted-access data is provided with the data.
The survey had national coverage
The lowest level of geographic aggregration covered by the dataset is province. Data that includes the full geo-coding is available for use at the NIDS operations office at the University of Cape Town.
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.
Producers and sponsors
Southern Africa Labour and Development Research Unit
University of Cape Town
Government of South Africa
Dates of Data Collection
Data Collection Mode
National Income Dynamics Study (NIDS) supervisory staff
Data Collection Notes
Fieldwork for NIDS Wave 3 commenced in April 2012 and was concluded in December 2012.
Registering to use the NIDS data includes agreement that the data user will not attempt to identify specific individuals from the data.
Secure Research Data Centre access https://www.datafirst.uct.ac.za/services/secure-data-services
Southern Africa Labour and Development Research Unit. National Income Dynamics Study Wave 3, 2012, Secure Data [dataset]. Version 3.0.0. Pretoria: SA Presidency [funding agency]. Cape Town: Southern Africa Labour and Development Research Unit [implementer], 2018. Cape Town: DataFirst [distributor], 2018. https://doi.org/10.25828/262r-8n47
The original collector of the data (The National Income Dynamics Study), the distributor (DataFirst), and the relevant funding agencies bear no responsibility for use of the data or for interpretations or inferences based upon such uses.