Gini index
The Gini index (a.k.a. Gini coefficient) is a measure of income inequality within a group, community, or society. The Gini index can range from 0 to 1. Lower values indicate greater equality, while higher values indicate greater inequality. For example, a country where everyone has the same income would have a Gini index of 0. More information on the Gini index can be found here.