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    HL

    Lorenz Curve – Measuring Income Inequality

    Macroeconomics

    This diagram shows the Lorenz Curve used to measure income inequality in an economy. It compares the actual distribution of income with a perfectly equal distribution.

    Diagram & Curves
    Lorenz Curve – Measuring Income Inequality

    Curves and Elements

    perfect equality

    The 45-degree yellow line represents perfect income equality.

    lorenz curve

    The blue Lorenz Curve represents the actual distribution of income.

    area a

    Area A is between the Lorenz Curve and the line of equality, used in calculating the Gini coefficient.

    area b

    Area B lies below the Lorenz Curve, also used in the Gini coefficient formula.

    gini formula

    Gini = A / (A + B), measuring income inequality from 0 (equality) to 1 (inequality).

    Key Explanations
    1

    The 45-degree yellow line represents perfect income equality, where each percentage of the population earns an equal share of total income.

    2

    The blue curved line is the Lorenz Curve, showing the actual cumulative distribution of income across the population.

    3

    Area A is the space between the line of perfect equality and the Lorenz Curve, while area B lies under the Lorenz Curve.

    4

    The Gini coefficient is calculated as A / (A + B) and ranges from 0 (perfect equality) to 1 (maximum inequality).

    5

    A more bowed-out Lorenz Curve indicates greater inequality, while a curve closer to the line of equality indicates a more equal income distribution.

    Example Exam Question
    Using a Lorenz Curve diagram, explain how the Gini coefficient can be used to measure income inequality.

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