Gini Coefficient

IntermediateMacroeconomics2 min read

Quick Definition

A statistical measure of income or wealth inequality within a population, ranging from 0 (perfect equality) to 1 (maximum inequality).

Key Takeaways

  • Ranges from 0 (perfect equality) to 1 (maximum inequality)
  • Derived from the Lorenz curve of cumulative income distribution
  • Most developed nations fall between 0.25 and 0.40
  • Used to evaluate tax policy, social programs, and economic development

What Is Gini Coefficient?

The Gini coefficient (or Gini index) quantifies the distribution of income or wealth across a population on a scale from 0 to 1 (or 0 to 100). A coefficient of 0 represents perfect equality where everyone earns the same, while 1 represents maximum inequality where one person holds all income. Developed by Italian statistician Corrado Gini in 1912, it is derived from the Lorenz curve, which plots cumulative income share against cumulative population share. Most developed nations have Gini coefficients between 0.25 and 0.40 for income. The Gini coefficient is used by economists, governments, and international organizations like the World Bank to track inequality trends and evaluate the impact of tax and social policies.

Gini Coefficient Example

  • 1Scandinavian countries have Gini coefficients around 0.25-0.28, reflecting relatively equal income distribution.
  • 2The U.S. Gini coefficient of approximately 0.39 is among the highest in developed nations.
  • 3South Africa has one of the world's highest Gini coefficients at around 0.63, reflecting extreme wealth inequality.