The Theil index is a statistic primarily used to measure economic inequality and other economic phenomena, though it has also been used to measure racial segregation - wikipedia 
Map of Economic Inequality in the United States using the Theil index. The Theil Index is always positive but the contributing components, (in this map counties), can be negative or positive. A high positive Theil index contribution value indicates more income than population while a negative value shows more population than income. A value of zero shows equality between population and income. - wikimedia
- wikimedia.org
The basic Theil index TT is the same as redundancy in information theory which is the maximum possible entropy of the data minus the observed entropy. It is a special case of the generalized entropy index. It can be viewed as a measure of redundancy, lack of diversity, isolation, segregation, inequality, non-randomness, and compressibility. It was proposed by econometrician Henri Theil at the Erasmus University Rotterdam.
# See also * Formula * Derivation from entropy * Decomposability * Applications * See also * References * External links