The UNU-WIDER World Income Inequality Database (WIID) collects and stores information on income inequality for developed, developing, and transition countries. The database and its documentation are available on this website.
WIID2 consists of a checked and corrected WIID1, a new update of the Deininger & Squire database from the World Bank, new estimates from the Luxembourg Income Study and Transmonee, and other new sources as they have became available. WIID2a contains fewer points of data than WIID1 as some overlaps between the old Deininger & Squire data and estimates included by WIDER have been eliminated along with some low quality estimates adding no information. In addition to the Gini coefficient and quintile and decile shares, survey means and medians along with the income shares of the richest 5% and the poorest 5% have been included in the update. In addition to the Gini coefficient reported by the source, a Gini coefficient calculated using a new method developed by Tony Shorrocks and Guang Hua Wan is reported. The method estimates the Gini coefficient from decile data almost as accurately as if unit record data were used.
The database will be updated and notifications and details on the updates will be given on the website. The letter denotes the version of the update. Some minor corrections can be done without a change of the database version. Please cite this database version as 'UNU-WIDER World Income Inequality Database, Version 2.0c, May 2008'.
Please contact the database manager for any questions on the database. We also encourage comments on this revision and contributions of updated data points.