What is the name of the measure of inequality that ranges from 0 (complete equality) to 1 (complete inequality)?

• A. Gini index
• B. Equality index
• C. Inequality score
• D. Poverty index

Answer: (A)

The Gini index is the standard way sociologists and economists summarize how unevenly resources are distributed. It comes from the Lorenz curve, which plots the share of total income earned by the bottom x percent of people. The Gini measures how far that curve is from the line of perfect equality. If everyone has the same income, the Lorenz curve sits exactly on that line and the Gini is 0. If all income goes to one person and the rest have nothing, the curve deviates the most from the line of equality and the Gini approaches 1. Because of this interpretation, the measure naturally ranges from 0 to 1, with 0 meaning complete equality and 1 meaning complete inequality. This is the standard index used to quantify inequality across populations or over time. The other terms listed aren’t the conventional 0-to-1 measure of inequality, so they don’t fit this description as neatly.