Cambridge IGCSE Economics: Supply-side policy, and measuring economic growth and recession (0455)

This guide teaches sections 4.5 and 4.6.1 to 4.6.3 of the Cambridge IGCSE Economics 0455 syllabus for examination in 2026: supply-side policy (4.5.1 to 4.5.3), the definition and measurement of economic growth (4.6.1 and 4.6.2), and recession (4.6.3). Economics 0455 is not tiered. The causes, consequences and policies of growth (4.6.4 to 4.6.6) are taught in a separate unit. Every country, firm and figure below is invented for practice and is not a real statistic.

Related pages: revision notes for this unit, practice questions for this unit, the Cambridge IGCSE Economics hub, the printable checklist, the exam preparation guide and the free diagnostics.

Outcomes this guide teaches

Section	Outcome
4.5.1	Define supply-side policy
4.5.2	Explain education and training, labour market reforms, lower direct taxes, deregulation, improved incentives to work and invest, and privatisation
4.5.3	Explain how these measures may help the government reach its macroeconomic aims
4.6.1	Define economic growth
4.6.2	Measure growth with real GDP and GDP per head, including calculations
4.6.3	Explain the meaning, causes and consequences of recession, and how it moves the economy within its PPC

4.5.1 What supply-side policy is

Supply-side policy is government action to raise the economy’s productive capacity, meaning how much it can produce when resources are fully used. It works by making labour, capital and markets more productive and efficient. It is not mainly about boosting spending. Fiscal and monetary policy change demand in the short run. Supply-side policy aims to shift the whole production possibility curve (PPC) outwards over the long run.

4.5.2 Supply-side measures

For each measure, write the chain: what the government does, who changes behaviour, what happens to output or costs, and the effect on the economy.

Education and training

The government funds schools, colleges and apprenticeships, or pays firms to train staff. Workers gain skills, so output per worker rises. Skilled workers also move more easily between jobs, which cuts structural unemployment.

Worked example (Bakery X, invented). Four workers are paid 400 a week in total and make 40 units each week, so labour cost per unit is 400 ÷ 40 = 10. After a training course funded by the government, the same workers make 50 units. Productivity has risen by (50 − 40) ÷ 40 × 100 = 25%. With wages unchanged, labour cost per unit falls to 400 ÷ 50 = 8, a fall of 20%.

Evaluation: spending takes years to pay off, costs the government money, and trained workers may emigrate or leave for rivals. The result depends on whether the skills match what employers need.

Labour market reforms

These make the labour market work with fewer rigidities. Examples: reducing the power of trade unions to block changes, making hiring and firing easier, reducing the minimum wage, and improving job information and retraining so workers can move between regions and occupations. Firms hire more readily and unemployed workers find vacancies faster, so unemployment falls and output rises.

Evaluation: weaker job protection can leave workers insecure and reduce spending. A lower minimum wage may cut incomes for low-paid workers. Gains depend on there being vacancies to fill.

Lower direct taxes

Direct taxes are paid by people and firms from income and profit, such as income tax and corporation tax. Cutting income tax raises take-home pay for each extra hour worked, so more people may choose to work or work longer. Cutting corporation tax raises the profit firms keep, which encourages investment.

Worked example (a worker in Country K, invented). Gross pay is 400 a week and the income tax rate is 30%, so take-home pay is 400 × 0.70 = 280. The rate is cut to 25%, and take-home pay becomes 400 × 0.75 = 300, a rise of 7.1%. On an extra hour paid at 20, the worker keeps 14 before the cut and 15 after it.

Evaluation: a tax cut reduces government revenue unless the extra work and spending bring in enough tax. Some people may work less because they can earn the same with fewer hours. Gains go mainly to higher earners, which can widen inequality.

Deregulation

Deregulation means removing rules that limit competition, such as licences that restrict who can open a business. More firms can enter, so competition rises, prices tend to fall, and firms are pushed to cut costs and innovate.

Evaluation: safety, environmental and consumer protections may weaken. Rules were often introduced to correct a market failure, and removing them can bring that failure back.

Improving incentives to work and invest

Incentives to work: lowering income tax, and reducing welfare benefits so that taking a job leaves a person clearly better off. Incentives to invest: investment grants, tax allowances for buying machinery, and a stable economy that makes firms confident about the future. More work and more capital raise potential output.

Evaluation: cutting benefits hurts those who cannot work and increases poverty. Grants cost the government money, and firms that would have invested anyway gain without changing their behaviour.

Privatisation

Privatisation is the sale of state-owned firms to the private sector. Owners seeking profit have an incentive to cut waste. Competition from other firms can increase efficiency and choice. The sale gives the government one-off revenue, and it no longer pays any subsidy.

Worked example (invented). A state railway loses 40 a year and the government sells it for 500. The sale price equals 500 ÷ 40 = 12.5 years of losses, and the loss no longer falls on taxpayers.

Evaluation: a private monopoly can raise prices. The new owner may close unprofitable but socially useful services. A one-off sale is not a lasting source of revenue.

4.5.3 Effects on the government’s macroeconomic aims

Aim	How supply-side policy may help	Limit
Economic growth	Higher productivity and more workers shift the PPC outwards	Slow to work; needs demand to use new capacity
Low unemployment	Skills and flexible labour markets match workers to jobs	Does not help cyclical unemployment when demand is weak
Stable prices	Lower costs and more output reduce cost pressure	Very small effect on inflation caused by high demand
Balance of payments	Cheaper, better exports; fewer imports needed	Depends on other countries’ demand and prices
Redistribution of income	Education and training may lift low earners	Lower taxes and benefits can widen inequality

Supply-side policy can ease conflicts between aims. Raising output capacity can allow growth with less pressure on prices, unlike a demand boost that runs into capacity limits. The cost is time: results may take many years, so governments often pair it with demand policies.

4.6.1 Economic growth defined

Economic growth is an increase in an economy’s output of goods and services over time. It is normally measured as the percentage change in real GDP. Growth in output is not the same as development or higher living standards for everyone.

4.6.2 Measuring economic growth

Gross Domestic Product (GDP) is the total value of goods and services produced in a country in a year. Nominal GDP uses prices of the year it is measured, so it rises when prices rise even if output is unchanged. Real GDP removes the effect of inflation by using constant prices. Only real GDP shows a true change in output.

Formulas:

• Real GDP = (nominal GDP ÷ price index) × 100
• Growth rate = (new − old) ÷ old × 100
• GDP per head = GDP ÷ population

Worked example 1: Country A (invented, base year is year 1). Nominal GDP is 800 (billion units) in year 1 and 858 in year 2. The price index is 100 in year 1 and 104 in year 2.

• Nominal growth = (858 − 800) ÷ 800 × 100 = 7.25%.
• Real GDP in year 2 = 858 ÷ 104 × 100 = 825.
• Real growth = (825 − 800) ÷ 800 × 100 = 3.1%.

Prices explain most of the gap between the two growth figures.

Worked example 2: Country B (invented). Nominal GDP rises from 600 to 648, up 8%. The price index rises from 100 to 112.5. Real GDP = 648 ÷ 112.5 × 100 = 576. Real growth = (576 − 600) ÷ 600 × 100 = −4.0%. A rising nominal figure hides a fall in output.

Worked example 3 (GDP per head, using Country A). Population is 40 million in year 1 and 41 million in year 2. Real GDP per head in year 1 = 800 000 million ÷ 40 million = 20 000. In year 2 it is 825 000 million ÷ 41 million = 20 122. Growth in GDP per head = (20 122 − 20 000) ÷ 20 000 × 100 = 0.6%. GDP grew 3.1% but each person’s share rose only 0.6%, because population grew 2.5%.

Worked example 4 (Country C, invented). Real GDP rises 5.0% from 1 200 to 1 260 billion while population rises from 60 to 63 million, also 5.0%. GDP per head is 20 000 in both years: total output has grown with no gain per person.

Limits of GDP per head: it is an average and hides inequality; it leaves out unpaid work and the informal sector; it ignores pollution and leisure; and it cannot show how good the goods and services are.

4.6.3 Recession

A recession is a period when real GDP falls. A common rule of thumb is a fall for two consecutive quarters, though the syllabus asks you for the meaning, not a fixed rule. The opposite of a recession is a period of positive growth.

Worked example 5 (Country G, invented). Real GDP by quarter is 250, 248, 245, 247.

• Quarter 2: (248 − 250) ÷ 250 × 100 = −0.8%.
• Quarter 3: (245 − 248) ÷ 248 × 100 = −1.2%.
• Quarter 4: (247 − 245) ÷ 245 × 100 = +0.8%. Output fell for two consecutive quarters, so the rule of thumb is met. From peak to trough the fall is (245 − 250) ÷ 250 × 100 = −2.0%.

Causes: a fall in consumer spending or confidence; a fall in investment; a fall in export demand when trading partners slow; higher interest rates or tight credit; cuts in government spending; a sudden rise in the price of a key input such as energy.

Consequences: unemployment rises; firms cut output, close or stop investing; incomes and living standards fall; tax revenue falls while spending on benefits rises, increasing the budget deficit; price rises slow and prices may fall; the number of people in poverty can increase.

Recession and the PPC

The PPC is the boundary of what the economy can make of two goods; a point on it means every resource is in use and none is wasted.

Capital goods
 |  *B  (before: on the PPC)
 |   \
 |    * A  (recession: inside the PPC)
 |     \
 +---------- Consumer goods

In a recession output falls, so the economy moves from a point on the PPC to a point inside it. Resources, especially labour and capital, are unemployed or underused. The curve itself has not moved, because the quantity and quality of resources have not changed in the short run. Recovery moves the economy back towards the curve. If a long recession leaves people out of work so long that their skills fade, or firms scrap machinery, the PPC itself can shift inwards.

Common errors

• Treating nominal GDP growth as real growth.
• Dividing by the index without multiplying by 100.
• Describing a recession as a shift of the PPC rather than a move inside it.
• Writing a list of supply-side measures with no chain of reasoning.
• Saying supply-side policy works quickly.
• Calling a rise in GDP per head an equal gain for everyone.

Official syllabus

Cambridge IGCSE Economics 0455 syllabus for examination in 2026, version 2, published by Cambridge University Press & Assessment: sections 4.5 Supply-side policy and 4.6 Economic growth (4.6.1 to 4.6.3).