Measuring Inequality and Poverty

Introduction: Why does this matter? 🌍

students, every economy produces income, but not everyone receives the same amount. Some households earn a lot, others earn very little, and some struggle to meet basic needs. Measuring inequality and poverty helps economists understand how income and living standards are shared across a country. This matters because a society can have rising total output and still leave many people behind.

In this lesson, you will learn how economists measure inequality and poverty, why these measures are useful, and how they connect to broader macroeconomic goals such as economic growth, full employment, and improved living standards. By the end, you should be able to explain key terminology, interpret common diagrams and indicators, and use real-world examples in IB Economics SL answers.

Learning objectives

Explain the main ideas and terminology behind measuring inequality and poverty.
Apply IB Economics SL reasoning to inequality and poverty questions.
Connect inequality and poverty to the wider topic of macroeconomics.
Summarize how these ideas fit into economic policy and long-run growth.
Use evidence or examples to support economic analysis.

What is inequality? 📊

Inequality describes an uneven distribution of income, wealth, or consumption across people or groups. In economics, the most common focus is income inequality, which looks at how money earned by households is shared. Wealth inequality is about assets such as property, savings, and investments. Wealth is often more unequal than income because wealth can build up over time and be passed between generations.

It is important to distinguish between relative poverty and absolute poverty. Relative poverty means having much less income than most people in the same society, so the person cannot participate fully in normal life. Absolute poverty means not having enough income to meet basic needs such as food, shelter, and clean water. This difference matters because a country can reduce absolute poverty while still having high relative poverty.

Another key idea is equity versus equality. Equality means everyone gets the same amount. Equity means resources are distributed more fairly, taking into account different needs and circumstances. For example, a child with a disability may need more support than others to achieve similar outcomes.

Why economists care

High inequality can affect economic performance. If low-income households have very little money, they may spend less on education, healthcare, or training. This can reduce human capital and long-run growth. On the other hand, some level of inequality can encourage work, innovation, and entrepreneurship. The IB focus is not on saying inequality is always good or always bad, but on understanding its causes, measurement, and effects.

How inequality is measured 📈

Economists use several tools to measure inequality. No single measure is perfect, so they often combine them.

1. Income shares

One simple method is to compare the share of total income earned by different groups. For example, the richest $10\%$ of households may earn $40\%$ of total income, while the poorest $20\%$ earn only $5\%$. This shows how income is distributed across the population.

Income shares are easy to understand, but they do not show the full distribution. Two countries could have the same top $10\%$ share but very different middle-income patterns.

2. Lorenz curve

The Lorenz curve is a graphical way to show inequality. It compares the cumulative percentage of income received by cumulative percentage of the population.

The horizontal axis shows the cumulative percentage of people, starting with the poorest.
The vertical axis shows the cumulative percentage of income.
The line of perfect equality is a $45^\circ$ line, where, for example, $20\%$ of the population receives $20\%$ of income.
The farther the Lorenz curve is from the line of equality, the greater the inequality.

For example, if the poorest $50\%$ of households receive only $20\%$ of total income, the Lorenz curve will lie well below the equality line.

3. Gini coefficient

The Gini coefficient is a numerical summary of inequality based on the Lorenz curve. It ranges from $0$ to $1$, or sometimes from $0$ to $100$.

$0$ means perfect equality.
$1$ means perfect inequality, where one person receives all income.

A higher Gini coefficient means greater inequality. For example, a country with a Gini coefficient of $0.28$ is more equal than a country with a coefficient of $0.45$. However, the Gini coefficient has limits: it gives one number for a complex distribution, so two countries with the same Gini value may still have different income patterns.

Example

Suppose Country A has a large middle class and moderate inequality, while Country B has a very rich top group and a large low-income population. Their Gini coefficients might be similar even though the social experience is different. This is why economists should interpret the Gini coefficient carefully, not in isolation.

Measuring poverty 🧾

Poverty measurement focuses on people who cannot achieve a minimum standard of living. Economists and governments use different approaches.

Absolute poverty line

An absolute poverty line is a fixed income level set to reflect the cost of basic needs. If a person’s income is below this line, they are counted as poor. International organizations sometimes use a global poverty line, adjusted for purchasing power, to compare poverty across countries.

Absolute poverty is useful because it shows whether people can meet essentials. However, it can miss social expectations that change over time. For example, internet access may not have been essential decades ago, but now it is important for education and job search.

Relative poverty line

A relative poverty line is usually set as a percentage of median income in a country. A common example is $60\%$ of median household income. This measures whether people are excluded from normal living standards in that society.

Relative poverty is useful in richer countries where basic survival may be less of the issue, but inequality and social exclusion are still important. In a high-income country, someone may not be starving but may still be unable to afford transport, school trips, or stable housing.

Multidimensional poverty

Income alone does not capture everything. Multidimensional poverty considers other factors such as education, healthcare, housing, nutrition, and clean water. A household could have a slightly higher income but still live in poor conditions if services are unavailable.

This approach is important because poverty is not just about money. For example, a child may attend a school with no textbooks, or a family may live in a region with poor sanitation. These conditions reduce well-being even if money income is not extremely low.

Why inequality and poverty are connected to macroeconomics 💡

In IB Economics, inequality and poverty are part of macroeconomics because they relate to overall living standards, growth, and government policy.

Effect on aggregate demand

Low-income households usually spend a larger proportion of their income than high-income households. This means if income is redistributed toward poorer households, total spending in the economy may rise, supporting aggregate demand. In contrast, very high inequality can reduce overall consumption if a large share of income goes to households that save more.

Effect on long-run growth

Poverty can reduce human capital because families may not afford education, healthcare, or nutritious food. This lowers productivity and slows long-run economic growth. Inequality may also reduce access to opportunity if poor households cannot invest in skills or start businesses.

Effect on social stability

Large and persistent inequality may lead to social tension, lower trust, and political pressure. Governments may then use taxes, transfers, or public services to reduce inequality and poverty. Stable societies often create better conditions for investment and growth.

Policies that affect inequality and poverty 🏛️

Governments can use macroeconomic policies to reduce inequality and poverty, although each policy has trade-offs.

Progressive taxation and transfers

A progressive tax system takes a higher percentage of income from higher earners. The government can then use that revenue for welfare payments, unemployment benefits, pensions, or child support. These transfers can raise incomes for low-income households.

Spending on merit goods

Governments often provide or subsidize merit goods such as education and healthcare. These services help reduce poverty by improving skills, health, and job opportunities. For example, free school meals can improve concentration and attendance.

Minimum wage and labor market policies

A minimum wage may increase earnings for low-paid workers, helping reduce in-work poverty. However, if set too high, it may cause unemployment for some workers. IB answers should always mention both the benefit and the possible drawback.

Economic growth and job creation

Growth can reduce poverty if it creates jobs and raises wages. But growth does not automatically reduce inequality. If growth mainly benefits high-income groups, the gap may widen. This is why economists talk about inclusive growth, meaning growth that is shared more broadly across society.

Using evidence in IB Economics SL responses 🔍

When answering exam questions, students, it helps to use clear evidence and precise terms.

For example, you might write: “If the Gini coefficient rises from $0.31$ to $0.39$, this suggests that income inequality has increased.” Or: “A relative poverty line set at $60\%$ of median income identifies households excluded from normal participation in society.”

If you use a diagram, explain what it shows. For the Lorenz curve, state whether the curve moves closer to or farther from the line of equality. If discussing poverty, explain whether the policy reduces the number of people below the poverty line or improves access to basic services.

A strong IB response should also explain limitations. For instance, the Gini coefficient does not show how income is split within the middle of the distribution, and an income poverty line does not measure access to healthcare or housing quality.

Conclusion ✅

Measuring inequality and poverty helps economists understand how well an economy is sharing its income and opportunities. Inequality is commonly measured using income shares, the Lorenz curve, and the Gini coefficient. Poverty is measured using absolute poverty lines, relative poverty lines, and multidimensional indicators. These measures are important in macroeconomics because they affect aggregate demand, human capital, long-run growth, and social stability.

For IB Economics SL, the key skill is not just naming the measure, but explaining what it shows, why it matters, and how policy can respond. Always link your answer to real outcomes such as living standards, opportunity, and economic growth.

Study Notes

Inequality means an uneven distribution of income, wealth, or consumption.
Wealth inequality is usually greater than income inequality.
Absolute poverty is based on a fixed minimum standard of living.
Relative poverty is based on income compared with the rest of society.
The Lorenz curve shows cumulative income distribution.
The line of perfect equality is a $45^\circ$ line.
The Gini coefficient ranges from $0$ to $1$; higher values mean more inequality.
A poverty line can be absolute, relative, or multidimensional.
Multidimensional poverty includes health, education, housing, and access to services.
High inequality can reduce consumption, human capital, and long-run growth.
Redistribution, merit goods, and welfare transfers can reduce poverty.
IB answers should include definitions, diagrams, analysis, and evaluation.