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, with possible values ranging from zero to 100. A GINI index of zero indicates perfect income equality, while a GINI index of 100 would imply perfect income inequality, where one individual earned 100% of all income. Some reports of the GINI Index use a scale from zero to one.
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.