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3.4 · SL & HL · 9 MIN

What Is Economic Inequality?

Inequality and poverty

What you will learn

  • Income is a flow, wealth is a stock, and equality is different from fairness.
  • Apply the model to an original scenario and justify its limits.

Essential definitions

Equality
The extent to which people receive the same economic outcomes.
Equity
A judgement about whether economic outcomes or opportunities are fair.
Income
A flow of receipts measured per period.
Wealth
The value of assets minus liabilities at a point in time.

What is being shared?

Economic inequality means differences in the resources people receive or own. It matters because income and wealth affect access to food, housing, education and security. Two households can have similar wages but very different opportunities if only one has savings or inherited property.

Income is received during a period: wages, rent, interest and profit are examples. Wealth is the value of assets minus debts at a date. Saving income can build wealth, while assets can generate future income. This link helps explain how advantage can accumulate across generations. We will first learn to measure distribution and poverty, then investigate causes and possible policy responses.

Equality and equity ask different questions

Equality describes how similar outcomes are. Equity concerns fairness, which requires a value judgement. Equal payments may seem fair for equal circumstances; different payments may seem fair when needs or responsibilities differ. State the criterion rather than using fair as if it were a statistic.

Equality of opportunity concerns access to education, finance and employment. Equality of outcome concerns the resulting incomes or wealth. A policy can improve opportunity without making every final income equal. Conversely, a short-term transfer may narrow income differences while leaving unequal access to schooling unchanged.

Make a meaningful comparison

Net wealth = assets − liabilities. Both are currency amounts valued at the same date. A household with assets of 300,000 and debts of 50,000 has wealth of 250,000; another with assets of 20,000 and debts of 30,000 has −10,000. Equal annual incomes do not remove this difference in resilience.

For income, distinguish market earnings from disposable income after taxes and transfers. Allow for household size and identify whether wealthy households, informal income or public services are captured. No single number answers every question. The next lessons introduce Lorenz curves and poverty measures so a distributional claim can be checked against suitable evidence.

WORKED EXAMPLE

Hypothetical worked application

  1. First net wealth = 300,000 − 50,000 = 250,000 currency units.
  2. Second net wealth = 20,000 − 30,000 = −10,000 currency units.

Equal annual income can coexist with unequal net wealth.

Apply and evaluate

  • A fair policy depends on an explicit fairness criterion and the population being compared.

Common misconceptions

  • Income is a flow; wealth is a stock. Equal income does not imply equal wealth.

Knowledge check

Can an unequal allocation be equitable?

Real-world application

Poverty lines depend on a PPP vintage

5 June 2025: The World Bank’s June 2025 update set the international extreme-poverty line at $3.00 per person per day in 2021 PPP international dollars, replacing $2.15 in 2017 PPP dollars.

The change is not an ordinary market-exchange-rate conversion. PPP data and the national poverty lines underlying the benchmark changed. Comparing poverty counts across releases requires a consistent method; a statistical revision is not itself proof that living conditions suddenly worsened.

World Bank, June 2025 update to global poverty lines ↗

Historical evidence checked 9 October 2026. The model interpretation is an original teaching application.

What to remember

Income is a flow, wealth is a stock, and equality is different from fairness. Identify which distribution and fairness criterion a policy is meant to address.

Completion is your own reflection on learning, not a test score. Syllabus references: 3.4.01, 3.4.02.

Sources and applications

Lessons in this section
  1. What Is Economic Inequality?
  2. How Do Lorenz Curves and Gini Coefficients Work?
  3. How Do We Draw a Lorenz Curve from Quintiles? · HL
  4. How Is Poverty Measured?
  5. Why Does Inequality Persist?
  6. How Do Taxes Affect Income Distribution?
  7. How Are Income Tax and Sales Tax Calculated? · HL
  8. How Can Transfers and Public Services Reduce Poverty?
  9. How Can Policy Support Incomes and Fair Access to Work?

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