Frequently asked questions

Q: What should I cite as the source when I use WIID for publications?
Please refer to the data set as:
UNU-WIDER, ‘World Income Inequality Database (WIID3.4)’, January 2017.

Q: Why are there several estimates reported per country and year?
Unlike national accounts data, there is no agreed basis of definition for the construction of income/consumption distribution data. In general, one can not consider any source to be 'the official one'. Several sources report estimates based on different surveys, income/consumption concepts, population concepts, weighting procedures etc. Our task is only to report these estimates, to try to give as a precise documentation as possible and to evaluate the quality of the estimates.

Q: How do I know which estimate to choose if several ones are reported per country and year?
The answer depends upon the purpose of the study in which the data will be used, but in general we would suggest the following:

  1. read the user guide to understand which set of underlying concepts we have defined as our preferred one and try to choose estimates according to that
  2. make sure that the quality rating is the highest possible
  3. if you use time series data for a country, strive to use data from the same source
  4. read the country information sheets to understand if there are any special features in any of the sources

Q: How can I import data extractions from WIID into Excel?
One needs to import or export to excel, rather than copy and paste in excel as the value labels may not be copied. In Stata, type import delimited using filename.ext, where filename.ext is the name of the file that you just saved in Excel. Give the complete filename, including the extension

Q: Does the welfare definition include remittances in Income category?
Disposable income, as a concept, differs from national income, in that, additional income items are included, mainly other current transfers such as remittances.

Q: Can the WIID data be used for comparing indices across time?
Yes, the Gini coefficient compared over same categories of Welfare definition, Equivalence Scale, Area coverage, population coverage, Age coverage and Source can be compared over time.

Q: What is the difference between gross income datasets and net income ?
Gross income includes income from market sources and cash benefits. Direct taxes and regular inter-household cash transfers paid are deducted from gross income to give disposable income.

Q: How can I find out when the data in the database are updated?
It will be indicated on the UNU-WIDER website here: https://www.wider.unu.edu/project/wiid-world-income-inequality-database

Q: How often is data updated on the web site?
It is likely to be updated annually.

Q: Where can I find definitions of the statistical terminology?- like Gini, Mean, P5,P95 etc
Please see the user guide for definitions. It is also advised to refer to the statistical methodology used by different sources of information for different definitions used in that source.

Q: Is it possible to have access to micro data on which WIID databases is based?
WIID does not work with micro datasets and is a repository of information from different sources of data.