Comprehensive Economics Development and Inequality Concepts for Students

What is economic development?

Economic development is the improvement of living standards through increases in income, education, health, and overall quality of life.

What is economic growth?

An increase in a country's total output or national income (GDP/GNI).

Income per capita formula

National Income ÷ Population

What does income per capita measure?

The average income earned per person.

What are four limitations of income per capita?

Ignores income inequality, education, health, quality of life, and the informal economy.

What three dimensions does the Human Development Index (HDI) measure?

Income, education, and life expectancy.

Income Index formula

(log(Income) − log(100)) ÷ (log(40,000) − log(100))

Life Expectancy Index formula

(Life Expectancy − 25) ÷ 60

Education Index formula

(2/3 × Adult Literacy) + (1/3 × Gross Enrollment)

HDI formula

(Income Index + Life Expectancy Index + Education Index) ÷ 3

Rule of 70 formula

70 ÷ Growth Rate

What does the Rule of 70 calculate?

The approximate number of years it takes for a variable growing at a constant rate to double.

Income per capita growth formula

Income Growth Rate − Population Growth Rate

Harrod-Domar growth formula

g = s ÷ k

What does s represent?

The savings (or investment) rate.

What does k represent?

The capital-output ratio.

How can a country increase growth in the Harrod-Domar model?

Increase the savings rate or decrease the capital-output ratio.

What is the main criticism of the Harrod-Domar model?

It assumes all savings become investment and ignores technology, institutions, and human capital.

What is the Lewis Model?

A model explaining development through the movement of labor from agriculture to manufacturing.

What happens in the Lewis Model?

Workers leave agriculture, manufacturing expands, and the economy industrializes.

Lewis Model assumption: surplus labor

Removing workers from agriculture does not reduce agricultural output.

Lewis Model assumption: industrial wage

Industrial wages remain constant.

Lewis Model assumption: profits

All industrial profits are reinvested.

Why is the Lewis Model criticized?

Its assumptions are unrealistic, especially unlimited surplus labor and constant wages.

What does the Lorenz Curve show?

The distribution of income across a population.

What does the 45° line on the Lorenz Curve represent?

Perfect equality.

What does a Lorenz Curve farther from the equality line indicate?

Greater income inequality.

What does the Gini Coefficient measure?

The degree of income inequality.

Higher Gini Coefficient means...

More inequality.

Lower Gini Coefficient means...

Less inequality.

Kuznets Ratio formula

Top 20% Income Share ÷ Bottom 40% Income Share

Palma Ratio formula

Top 10% Income Share ÷ Bottom 40% Income Share

Quintile Ratio formula

Top 20% Income Share ÷ Bottom 20% Income Share

What is absolute poverty?

Inability to meet basic human needs.

What is relative poverty?

Poverty measured compared to the rest of society.

Headcount Index formula

Number of Poor ÷ Total Population

Total Poverty Gap formula

Σ(Poverty Line − Income of each poor person)

Average Poverty Gap formula

Total Poverty Gap ÷ Total Population

Average Income Shortfall formula

Total Poverty Gap ÷ Number of Poor

Why does inequality slow development?

It limits education, healthcare, credit access, and economic opportunity.

Population growth formula

(Birth Rate − Death Rate) ÷ 10

What happens if income growth exceeds population growth?

Income per capita increases.

What happens if population growth exceeds income growth?

Income per capita decreases.

What happens if income growth equals population growth?

Income per capita stays the same.

What is a stable equilibrium?

If the economy moves slightly away, it naturally returns.

What is an unstable equilibrium?

If the economy moves slightly away, it continues moving farther away.

What are children considered in the Household Fertility Model?

An economic good.

Maximum children formula

Income ÷ Price of Child

Maximum goods formula

Income ÷ Price of Goods

What happens when household income increases?

The budget line shifts outward in a parallel manner.

What happens when the price of children decreases?

The budget line rotates outward along the children axis.

What happens when the price of children increases?

The budget line rotates inward.

What usually happens to the number of children when their price falls?

Families choose more children.

What is the Harris-Todaro Model?

A model explaining rural-to-urban migration based on expected wages.

Expected Wage formula

Manufacturing Wage × (Manufacturing Employment ÷ Urban Labor Force)

Why do workers migrate to cities?

Because the expected urban wage exceeds the agricultural wage.

What happens when labor unions increase manufacturing wages?

Firms hire fewer manufacturing workers.

Why does the agricultural wage fall after manufacturing wages increase?

Workers leave manufacturing and enter agriculture, increasing labor supply and lowering wages.

Does unemployment exist immediately after the manufacturing wage increases?

No. Initially displaced workers move to agriculture.

Why does urban unemployment develop?

Workers continue migrating because expected urban wages remain attractive.

Why does child labor occur in the Child Labor Model?

Adult wages are too low to support the household.

What happens to child labor when adult wages increase?

Child labor decreases.

Why is the middle equilibrium unstable in the Child Labor Model?

Small changes push the economy toward either the low-wage or high-wage equilibrium.

What happens at the high-wage equilibrium?

Children attend school instead of working.

What is human capital?

The education, skills, training, and health that increase worker productivity.

Why is education considered an investment?

It increases future earnings and productivity.

Opportunity cost of education

The wages given up while attending school.

Examples of direct costs of education

Tuition, books, transportation, and school fees.

Examples of benefits of education

Higher future wages, greater productivity, and better employment opportunities.

Decision rule for investing in education

Invest if the benefits exceed the total costs.

What graph shows income inequality?

Lorenz Curve.

What graph shows development and inequality over time?

Kuznets Curve.

What graph has multiple stable and unstable equilibria?

Malthusian Model and Child Labor Model.

What graph uses a budget line with children and goods?

Household Theory of Fertility.

What graph explains rural-to-urban migration?

Harris-Todaro Model.

What model connects savings to economic growth?

Harrod-Domar Model.

What model explains structural transformation from agriculture to manufacturing?

Lewis Model.

What should you do first when solving an HDI problem?

Calculate the three indices separately before averaging them.

Can you use ln instead of log in the HDI formula?

Yes. The logarithm base cancels out, so ln and log produce the same answer.

If a Lorenz Curve becomes more bowed, what happens to the Gini Coefficient?

It increases.

If income grows faster than population, what happens to living standards?

Income per capita increases.

If a labor union raises manufacturing wages, what happens to manufacturing employment?

It decreases.

If manufacturing employment decreases, what happens to agricultural wages?

They decrease because more workers enter agriculture.

What is the biggest weakness of income per capita as a measure of development?

It ignores income distribution and other aspects of well-being.

What happens to inequality during the early stages of development according to the Kuznets Curve?

It increases.

What happens to inequality during the later stages of development according to the Kuznets Curve?

It decreases.

Why does inequality increase early in development?

Industrial workers earn more than agricultural workers.

Why does inequality decrease later in development?

Education, redistribution, and broader economic opportunities spread income more evenly.

What area under the labor demand curve represents workers' income?

The rectangle (wage × employment).

What area under the labor demand curve represents capitalists' profits?

The triangle above the wage line and below the labor demand curve.

What happens when the price of children doubles while income stays the same?

The budget line rotates inward and families can afford fewer children.

What happens when income doubles but prices stay the same?

The budget line shifts outward in parallel.

In the Malthusian Model, what happens if income growth is greater than population growth?

Income per capita rises.

In the Malthusian Model, what happens if population growth is greater than income growth?

Income per capita falls.

In the Harris-Todaro Model, why don't workers stop migrating when unemployment exists?

Because they care about the expected wage, not the guaranteed wage.

Why does raising the manufacturing wage not eliminate poverty?

Fewer workers are hired, agricultural wages fall, and unemployment may increase.