The GINI Index, also known as the GINI Coefficient, is a measure of income inequality. It represents the spread between low and high-income earners. Possible values range from zero to one. A GINI Index of zero indicates perfect income equality, while a GINI Index approaching one would indicate an extreme level of income inequality, where one individual earned 100% of all income.
One drawback of the GINI Index is that any given value can represent multiple different income distribution scenarios. Measurement is affected by demographics; societies with a greater number of young people or the elderly can rate higher on the GINI Index even if the income distribution for wage earners remains constant.