Standardized World Income Inequality Database

University Of Iowa, Iowa City IA

Investigators

Abstract

General Summary The Standardized World Income Inequality Database (SWIID) aims to provide data on income inequality for the broadest possible sample of countries and years that are made as comparable as possible. Income inequality is an enduring focus of inquiry in the social sciences that has attracted renewed attention from policymakers and the public. Economists, political scientists, sociologists, and other social scientists have long sought to explain why incomes are relatively equal in some countries and times and much larger disparities between rich and poor are found in others. The effects of income inequality on other forms of social inequality, such as health disparities, and on other phenomena ranging from political violence to economic growth to democratic transitions are similarly vital questions. The reliability of the results of these investigations and any policy interventions they suggest, depend crucially on the quality of the income-inequality data they employ; the SWIID is therefore a data infrastructure project that is central to the promotion of scientific progress on these topics. Technical Summary The SWIID surpasses other inequality datasets by directly addressing their tradeoff between coverage of countries over time and the comparability of the data they supply. It does so by using model-based multiple-imputation methods on data drawn from regional collections, national statistical offices, and academic studies to generate estimates for the missing country-years in the high-quality but sparse Luxembourg Income Study dataset. It currently provides comparable estimates of market- and net-income inequality for 174 countries for as many years as possible from 1960 to the present. The proposed research comprises four principal activities to improve the SWIID project: (1) acquiring and cleaning data to expand its coverage, (2) assessing and improving the multiple-imputation techniques used to ensure its estimates are comparable, (3) expanding documentation to help researchers use income-inequality data in ways appropriate to their research questions, and (4) improving the web-based system for disseminating the SWIID to researchers, educators, and policymakers worldwide. The SWIID has been used by thousands of researchers around the world working in academia, governments, non-governmental organizations, international organizations, and news agencies. Expanded and refined versions of the SWIID will make improved knowledge on income inequality even more accessible to policymakers and the public as well as to researchers and educators.