Based on Lorenz Curve, a standard economic measure of income inequality. Perfect equality in income distribution scores 0.0 on the Gini scale for that society. Higher the inequality, higher the number over 0. If only one person has all the income, a score of 1.0 (or 100) indicates total inequality. Market share inequality and other distributional inequalities can be measured this way. The Italian statistician Corrado Gini (1884-1965) is its inventor. Known also as Gini coefficient or index of concentration.