Global Income Inequality

Historical Trends in Global Poverty and Income

Global income inequality has evolved dramatically over the past centuries. Before the modern era, most people lived in extreme poverty, with only a few individuals considered wealthy by the standards of their time. The "hockey stick" pattern in economic history refers to a sharp upward turn in income and living standards, particularly after the seventeenth century.

• Extreme Poverty: Historically, the majority of the world population struggled to meet basic needs such as nutrition, shelter, and access to electricity, education, and healthcare.

• Modern Improvements: Today, approximately one in ten people live in extreme poverty, a significant reduction compared to previous centuries.

• Purchasing Power Parity (PPP): Economists use PPP to compare incomes across countries, adjusting for differences in price levels.

• Example: In 2019, the average daily income in China was $14.70, while in India it was $4.50, measured in international dollars (PPP-adjusted).

Income Inequality Between Countries

While income differences within regions existed historically, the gap between countries was relatively small. Today, the world exhibits significant disparities in average income between nations.

• Global Distribution: Countries are ranked by average income, with population size reflected in the width of each bar in distribution charts.

• Richest vs. Poorest: The richest countries (e.g., United Arab Emirates, US, Norway) have much higher average incomes than the poorest (e.g., South Sudan, Nigeria).

• Example: In 2020, Norway's average income was nearly seven times that of Nigeria.

Income Inequality Within Countries

Income inequality is not only a global phenomenon but also exists within individual countries. The distribution of income among decile groups (each representing 10% of the population) reveals substantial differences between the richest and poorest segments.

• Decile Groups: Each country’s population is divided into ten deciles, from the poorest 10% to the richest 10%.

• Rich/Poor Ratio: The ratio of average income between the richest and poorest deciles is a key measure of inequality.

• Examples:

  • Norway: Rich/poor ratio = 66

  • US: Rich/poor ratio = 244

  • Botswana: Rich/poor ratio = 489

  • Nigeria: Rich/poor ratio = 174

  • India: Rich/poor ratio = 246

• Trends: Income distributions have become more unequal in many richer and middle-income countries since 1980, with the richest deciles experiencing significant income growth.

Visualizing Global Income Distribution

Figures and visualizations (such as "skyscraper" charts) help illustrate the distribution of income both within and between countries. These charts show the average income for each decile group and highlight the emergence of "skyscrapers"—very tall columns representing the richest groups in wealthy countries.

• Skyscraper Effect: The tallest columns represent the richest 10% in the richest countries, e.g., the United Arab Emirates in 2020 ($390,000 per capita).

• Population Representation: The width of each bar indicates the country’s population size, with China and India having the widest bars.

Comparative Table: Rich/Poor Income Ratios (2020)

The following table summarizes the rich/poor income ratios for selected countries, illustrating the degree of income inequality within each nation.

Additional info: Average daily income values are approximate and based on PPP-adjusted international dollars. Rich/poor ratios are calculated as the ratio of the average income of the richest decile to the poorest decile.

Key Concepts and Definitions

• Extreme Poverty: Living on less than a defined threshold (often $1.90 per day, PPP-adjusted), lacking access to basic needs.

• Purchasing Power Parity (PPP): An economic metric that adjusts income and price levels to allow meaningful comparisons across countries.

• Income Deciles: Population groups divided into ten equal parts based on income, from the poorest to the richest.

• Rich/Poor Ratio:

Applications and Exercises

• Historical Comparison: In the fourteenth century, income differences between countries were minor compared to today, but within-region inequality existed.

• Data Analysis: Students can use interactive visualizations to compare rich/poor ratios across countries and over time, describing differences and trends.

• Example Exercise: Choose five countries, find their rich/poor ratios for 1980, 2000, and 2020, and analyze the changes.

Summary

Global income inequality is shaped by both historical and contemporary factors. While extreme poverty has declined, significant disparities persist both between and within countries. Understanding these patterns is essential for analyzing economic growth, development, and policy interventions in macroeconomics.