Standardized income inequality data for use in cross-national research

This article introduces the first version of a new, standardized data tool that can be used to test models of global income allocation, the Standardized Income Distribution Database (SIDD). It is based on a comprehensive collection of income distribution data compiled by the United Nations University's World Institute for Development Economics Research (UNU-WIDER 2000). International and intertemporal inconsistencies in these data have historically limited its use. We estimate adjustment factors for different scopes of coverage, income definitions, and reference units which, when applied to the raw data, bring all data to a common standard based on national coverage, gross income, and household per capita inequality. Criterion validity checks confirm that these adjustments boost the correlation between measured income inequality and national social indicators. The SIDD is also clean, free of duplicates, and easy to access. The SIDD will be useful both to students reading income inequality and to those conducting broad cross-national research on the relationship between income inequality and a range of important outcomes, such as health, criminality, and social support.