Following up on our previous post on wealth, this post focuses on resources that can be used to learn about income distribution. Income distribution within countries is often measured by the Gini Index. Devised by the Italian statistician, Corrado Gini in 1912, the scale for the Index runs from 0 (perfect equality of income) to 100 (perfect income inequality). A Gini Index of 0 would indicate that everyone had the same income. A Gini Index of 100 would indicate that one person had all the income. In the U.S., the Gini Index is calculated annually by the Census Bureau. You can find a graph or table of the index from 1967 to date on Bloomberg.
For a table, type GINI [Index] HP
The Gini index was .463 as of 12/31/11. Its low was .351 at the end of 1968.
For a discussion on the U.S. income distribution including the Gini Index, as well as alternative measures (such as at the Theil Index and Atkinson Index) see the Current Population Report “Income, Poverty and Health Insurance Coverage in the U.S. 2011” (September 2012). This report also includes shares of aggregate household income by percentile.
Here are some additional Gini sources:
Graph from “An Overview of Growing Income Inequalities in OECD Countries: Main Findings” (OECD, 2011).
Download the World Income Inequality Database from the UN’s University World Institute for Development Economics Research (UNU-WIDER). Considered the largest database of GINI coefficients.
Go to Income Gini Coefficient – International Human Development Indicators. This source shows an income Gini coefficient for the U.S. of 40.8 in the year 2000.
Take a look at World Development Indicators from the World Bank for the GINI Index for selected countries and years.
For a detailed examination of the characteristics of the Gini Index and how to calculate it, see the FAO report, “Inequality Analysis: The Gini Index”.