measure of dispersion Gini index https://search.r-project.org/CRAN/refmans/dineq/html/gini.wtd.html COKA group The Gini index, or Gini coefficient, is a statistical measure of dispersion which assesses the pattern of data in a frequency distribution, in particular it measures the inequality among values. Geometrically, the Gini index can be defined as the ratio of 2 areas delineated by 2 curves, the line of equality (curve 1) and the Lorenz curve (curve 2). The numerator of the ratio corresponds to the area defined between curve 1 and curve 2 , while the denominator corresponds to the entire area below curve 1. Mathematically, the Gini index is defined as half of the relative mean absolute difference. It was therefore originally used to assess income inequality and is named after the italian statistician Corrado Gini who published it in 1912.