The Gini coefficient is a measure of the inequality of a distribution, where a value of 0 expresses total equality and a value of 1 maximal inequality. It has found application in the study of inequalities in disciplines as diverse as sociology, economics, health science, ecology, chemistry, engineering and agriculture.
For example, in ecology the Gini coefficient has been used as a measure of biodiversity, where the cumulative proportion of species is plotted against cumulative proportion of individuals.
While developed European nations and Canada tend to have Gini indices between 0.24 and 0.36, the United States’ and Mexico’s Gini indices are both above 0.40, indicating that the United States (according to the US Census Bureau) and Mexico have greater inequality.
Using the Gini coefficent can help quantify differences in welfare and compensation policies and philosophies. However it should be borne in mind that the Gini coefficient can be misleading when used to make political comparisons between large and small countries. The Gini index for the entire world has been estimated by various parties to be between 0.56 and 0.66.
I created an interactive dashboard of the GINI coefficient and other world country statistics from the CIA Fact Book and used it to identify the top ten highest GINI coefficient countries and the US position as follows on a 100 point scale: Honduras 56.3, Nicaragua 60.3, Colombia 57.10, Brazil 60.70, Bolivia 58.9, Paraguay 57.7, Chile 56.7, Sierra Leone 62.9, Central African Republic 61.3, and South Africa 59.3. The United States at 40.8 is ranked about 40th out of 239 Counties.
So while the United States has greater inequality (40.8) according to the U.S. Census Bureau than countries such as Canada, France, Spain, and Australia (see map above), it is lower than the world average index (0.60 ) and is not among the top ten countries (62.9-56.3).