Causes and examples of uneven income distribution

Income distribution refers to how a country's total earnings are shared among its population. In many places, this distribution is uneven, leading to significant differences in living standards.

Factors contributing to uneven income distribution

• Ownership of assets - A small group of people often control key income-generating resources, such as land, which limits opportunities for others to earn.
• Economic transitions - Shifts from centrally planned systems to market-based economies, as seen in Eastern Europe, can widen gaps because only a few individuals quickly capitalise on new business chances.

Global patterns of income inequality

• High inequality regions - Countries in Latin America, along with South Africa and Lesotho, show particularly stark divides, with a small elite holding most wealth while many live in poverty.
• Low inequality regions - Scandinavian countries in Europe tend to have more balanced distributions, often due to policies promoting fair sharing of resources.
• Variations within Europe - While transitions in Eastern Europe generally increased inequality, nations like Slovenia and Ukraine maintain some of the most even income spreads on the continent.

The Gini coefficient as a measure of inequality

The Gini coefficient provides a numerical way to assess how equally income is spread across a population.

Key features of the Gini coefficient

• Range of values - It ranges from 0 (perfect equality, where everyone has the same income) to 1 (complete inequality, where one person receives all income).
• Practical application - Real-world values fall between 0 and 1, with higher numbers indicating greater inequality.
• Gini index variant - Sometimes presented as an index by multiplying the coefficient by 100, making it easier to interpret as a percentage-like score.

How to calculate and interpret the Gini coefficient

The Gini coefficient is derived from the Lorenz curve, focusing on the areas within the diagram to quantify inequality.

Formula for the Gini coefficient

$\text{Gini coefficient}=\frac{\text{area A}}{\text{area A}+\text{area B}}$

Where:

• Area A = The space between the line of perfect equality and the Lorenz curve
• Area B = The space under the Lorenz curve

Interpreting Gini coefficient values

• Value close to 0 - Suggests a highly equal distribution, with minimal differences in income shares.
• Value close to 1 - Indicates extreme inequality, where income is concentrated among very few people.
• Example interpretation - A coefficient of 0.41 (or index of 41) for a country like Argentina in 2018 points to moderate inequality, meaning income is somewhat concentrated among wealthier groups.

Worked example - Calculating the Gini coefficient

In a Lorenz curve diagram for a hypothetical country, area A (between the line of equality and the curve) is 0.22, and area B (under the curve) is 0.28. Calculate the Gini coefficient and interpret its meaning.

Step 1: Identify the values

• Area A = 0.22
• Area B = 0.28

Step 2: Apply the formula

$\text{Gini coefficient}=\frac{0.22}{0.22+0.28}$

Step 3: Perform the calculation

$\text{Gini coefficient}=\frac{0.22}{0.50}=0.44$

Step 4: Interpretation

A Gini coefficient of 0.44 indicates moderate-to-high inequality, where income is not evenly distributed and shows significant concentration among a smaller portion of the population.

The Lorenz curve and its use in illustrating inequality

The Lorenz curve is a graphical tool that visually represents how income or wealth is distributed across a population, making it easier to see deviations from equality.

Constructing the Lorenz curve

• Axes of the curve - The horizontal axis shows the cumulative percentage of the population (from poorest to richest), while the vertical axis shows the cumulative percentage of total income or wealth.
• Line of equality - A straight 45-degree diagonal line represents perfect equality, where each portion of the population receives an equal share of income (e.g., 50% of people get 50% of income).
• Actual distribution line - The curve plots the real shares, starting from the bottom-left and bending towards the top-right.

Analysing inequality with the Lorenz curve

• Distance from equality - The greater the curve's bow away from the 45-degree line, the more unequal the distribution, as lower-income groups receive disproportionately small shares.
• Uses in comparison - By overlaying curves for different countries or time periods, economists can compare inequality levels visually.