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Population Review

Gini Coefficient (Gini Index)

Definition

A measure of income inequality on a scale of 0 to 100. A score of 0 represents perfect equality (everyone earns the same), while 100 represents perfect inequality (one person earns everything).

Why It Matters

The Gini Index reveals how evenly income is distributed within a population. High inequality is associated with lower economic mobility, worse health outcomes, higher crime, and social instability.

How It's Measured

Calculated from the Lorenz curve, which plots the cumulative share of income against the cumulative share of the population. The Gini coefficient is the ratio of the area between the Lorenz curve and the line of perfect equality.

Current Value

US Gini: approximately 39.8; World range: 24 (Slovakia) to 63 (South Africa)

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Frequently Asked Questions

A measure of income inequality on a scale of 0 to 100. A score of 0 represents perfect equality (everyone earns the same), while 100 represents perfect inequality (one person earns everything).

The Gini Index reveals how evenly income is distributed within a population. High inequality is associated with lower economic mobility, worse health outcomes, higher crime, and social instability.

Calculated from the Lorenz curve, which plots the cumulative share of income against the cumulative share of the population. The Gini coefficient is the ratio of the area between the Lorenz curve and the line of perfect equality.