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Lorenz Curve vs Gini Coefficient

Lorenz Curve and Gini Coefficient are two Market Failure & Government concepts in AP Economics that students often mix up. In short: lorenz curve is the Lorenz curve is a graphical representation of income or wealth distribution within a population, comparing actual distribution to perfect equality. Meanwhile, gini coefficient is the Gini coefficient is a numerical measure of income or wealth inequality ranging from 0 (perfect equality) to 1 (perfect inequality). Here is how they compare side by side.

Lorenz Curve

The Lorenz curve is a graphical representation of income or wealth distribution within a population, comparing actual distribution to perfect equality.

It plots cumulative percentages of income against cumulative percentages of households, with perfect equality shown as a 45-degree line. The further the curve is from this line, the greater the inequality. It is used to visualize the extent of income disparity in a society.

Gini Coefficient

The Gini coefficient is a numerical measure of income or wealth inequality ranging from 0 (perfect equality) to 1 (perfect inequality).

It is calculated as the ratio of the area between the Lorenz curve and the line of perfect equality to the total area under the line of perfect equality. A higher Gini coefficient indicates greater inequality. It is commonly used to compare income distribution across countries or over time.

Gini Coefficient = Area between Lorenz curve and line of equality / Total area under line of equality

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