IB DP Economics: Supply-side policies

This guide follows the IB Diploma Programme Economics guide (first assessment 2022, published February 2020), the course examined from the 2022 session onwards. It covers sub-topic 3.7, Supply-side policies, in Unit 3 Macroeconomics. The sub-topic is part of the core syllabus for both SL and HL, and the guide marks none of its content as HL only.

All countries, firms and figures below are invented for illustration. Use the revision notes for recall, then the practice set. The Economics hub and the printable checklist show where 3.7 sits in the course, and the free diagnostics show what to revise first.

What 3.7 asks you to do

Content in the guide	Depth the guide sets	Diagram the guide lists
Goals of supply-side policies	Application and analysis	None
Market-based policies: competition, labour market and incentive-related	Application, analysis and skills	AD/AS model with the LRAS curve; minimum wage
Interventionist policies	Application and analysis	None listed
Demand-side effects of supply-side policies	Application and analysis	None listed
Supply-side effects of fiscal policies	Application and analysis	None listed
Effectiveness: constraints and strengths	Synthesis and evaluation	None listed

The last row matters most for essays. You are expected to weigh policies, not only describe them.

Goals of supply-side policies

A supply-side policy tries to expand what the economy can produce, or to make markets more efficient, instead of changing total spending. The guide lists five goals:

• Long-term growth by increasing productive capacity.
• Better competition and efficiency.
• Lower labour costs and unemployment through labour market flexibility.
• Lower inflation, which improves international competitiveness.
• Stronger incentives to invest in innovation by reducing costs.

These goals link directly to the two broad families of policy: market-based policies, which free markets and change incentives, and interventionist policies, where the government provides or funds something directly.

Market-based policies

Policies that encourage competition

• Deregulation scraps rules that block entry or restrict firms’ behaviour. Easier entry raises competitive pressure, so firms cut costs and prices.
• Privatization transfers ownership of a firm from the state to private owners. The profit motive and the threat of takeover or failure push managers towards efficiency.
• Trade liberalization lowers barriers to imports. Domestic firms face foreign rivals, and they can buy cheaper inputs.
• Anti-monopoly regulation blocks mergers or abuses of market power, which keeps prices down and widens consumer choice.

Labour market policies

• Reducing the power of labour unions lowers the wage and non-wage costs that bargaining can add, and makes hiring and reorganising easier.
• Reducing unemployment benefits raises the cost of staying out of work, so job seekers accept offers sooner. This targets frictional and structural unemployment.
• Abolishing minimum wages lets the wage fall to the market-clearing level.

Incentive-related policies

• Personal income tax cuts raise the reward for working longer hours, taking a job or seeking promotion.
• Cuts in business tax and capital gains tax raise the after-tax return on investment, so firms invest and innovate more.

Diagram 1: AD/AS model and the LRAS curve

The guide asks you to show the effect of supply-side policies on the AD/AS model with a long-run aggregate supply (LRAS) curve. The axes are the price level (vertical) and real output (horizontal). A successful policy raises the quantity or quality of factors of production or raises efficiency, so potential output rises and LRAS shifts right.

Price level
 |            LRAS1     LRAS2
 |              |         |
 P1 -----------(*)        |
 |              |  \      |
 P2 ------------|---(*)---|---- AD
 |              |         |
 +--------------+---------+------ Real output
               Y1         Y2

Label the original equilibrium at Y1 and P1, and the new equilibrium at Y2 and P2. Draw the new LRAS to the right of the old one, and keep the AD curve unchanged at first.

Worked example (fictional country Velmora). Potential output rises from 500 to 550 billion crowns after a package of competition and training policies.

1. Percentage rise in potential output = (550 − 500) / 500 × 100 = 10%.
2. Suppose AD is P = 170 − 0.1Y. At Y = 500, P = 170 − 50 = 120. At Y = 550, P = 170 − 55 = 115.
3. The price level falls by (115 − 120) / 120 × 100 ≈ −4.2%, while real output rises by 10%.

So the policy raises growth and lowers the price level at the same time. That is why the guide links supply-side policy to both growth and low inflation.

Diagram 2: the minimum wage

The minimum wage diagram is on the list in the guide. Plot the wage up the vertical axis and labour (workers) along the horizontal axis. Demand for labour slopes down and supply of labour slopes up. A minimum wage set above the equilibrium wage creates a surplus of labour, which is unemployment.

Read the diagram from left to right along the horizontal line at the minimum wage:

Point on the horizontal axis	Meaning
Qd	Where the minimum wage line meets the demand curve: workers employers want to hire
Qe	Where demand and supply cross, at the equilibrium wage We: the market-clearing employment
Qs	Where the minimum wage line meets the supply curve: workers who want a job at that wage

The order along the axis is Qd, then Qe, then Qs.

Qd is the quantity of labour demanded at the minimum wage, Qs the quantity supplied, and Qs − Qd the unemployment. Abolishing the minimum wage moves the market back to We and Qe.

Worked example (hairdressing in Kestrel Bay, fictional). Labour demand is Qd = 600 − 20W and supply is Qs = 100 + 30W, where Q is workers and W is the hourly wage in crowns.

1. Equilibrium: 600 − 20W = 100 + 30W, so 500 = 50W and W = 10. Then Q = 600 − 200 = 400 workers.
2. A minimum wage of 12: Qd = 600 − 240 = 360. Qs = 100 + 360 = 460.
3. Unemployment in this market = 460 − 360 = 100 workers, or 100 / 460 ≈ 21.7% of those seeking work.
4. Jobs lost = 400 − 360 = 40, a fall of 10%. The wage rises by 20%.
5. Total wages paid rise from 10 × 400 = 4,000 to 12 × 360 = 4,320. Workers who keep jobs gain; 40 lose them and 100 are unemployed.

Abolishing the minimum wage in this model removes the 100-worker surplus, though a real labour market may not match the model.

Interventionist policies

Here the government spends or organises directly. The guide lists:

• Education and training, which raise the skills of the labour force and so labour productivity.
• Quality, quantity and access to health care, which improve the health, and so the productivity and participation, of workers.
• Research and development, which creates new technology and ideas that private firms may under-provide.
• Provision of infrastructure, such as transport and communication links, which cut firms’ costs.
• Industrial policies, where the government supports chosen sectors, for example by subsidy or targeted investment.

All of these raise the quantity or quality of factors of production, or the efficiency with which they are used. In the AD/AS model they shift LRAS to the right, as in Diagram 1.

Worked example (training in Velmora). A programme costs 60 million crowns and trains 12,000 workers. Each trained worker produces an extra 1,800 crowns a year.

1. Cost per worker = 60,000,000 / 12,000 = 5,000 crowns.
2. Extra output per year = 12,000 × 1,800 = 21.6 million crowns.
3. Payback = 60 / 21.6 ≈ 2.8 years of output gains, if the workers stay employed.

The calculation ignores the years of delay before training starts to pay off, which is one reason the guide lists time lags as a constraint.

Demand-side effects of supply-side policies

Supply-side policies are not neutral for aggregate demand (AD). Be ready to explain this link:

• A personal income tax cut raises disposable income, so consumption rises and AD shifts right.
• A business tax cut may raise investment, a component of AD, as well as capacity.
• Spending on infrastructure, education or health is government spending, so AD rises when the spending happens, before capacity increases.
• Lower costs and prices can raise net exports, because domestic goods are more competitive abroad.
• Cuts in unemployment benefits may reduce the spending of the people who lose income.

Return to Velmora. Suppose a tax cut also moves AD to P = 180 − 0.1Y. At Y = 550, P = 180 − 55 = 125. The price level now sits at 125, up (125 − 120) / 120 ≈ 4.2% from the start, instead of falling to 115. Output is still 550. The demand-side effect has offset the price fall, which is a useful point when you evaluate the inflation goal.

Supply-side effects of fiscal policies

Fiscal policy means the government’s choices on taxation and spending. The guide asks you to recognise that fiscal choices can work on the supply side too, not only on AD:

• Lower taxes on income and business profits change incentives to work, save and invest.
• Spending on education, health care, research and infrastructure raises productive capacity over time.

Worked example (income tax in Velmora). The top rate for a group of 2,000 workers falls from 30% to 25%. Each earns 40,000 crowns.

1. Take-home pay on each extra 100 crowns earned rises from 70 to 75, a rise of 5 / 70 ≈ 7.1%.
2. Take-home pay on 40,000 rises from 28,000 to 30,000.
3. Revenue before: 2,000 × 40,000 × 0.30 = 24 million crowns.
4. Suppose taxable income rises 6% because people work more. Revenue after = 2,000 × 40,000 × 1.06 × 0.25 = 21.2 million crowns.
5. Revenue falls by 2.8 million, or about 11.7%.

The assumed 6% rise drives the result: a bigger response shrinks the loss.

Effectiveness of supply-side policies

This is the AO3 part of the sub-topic. The guide sets out constraints and strengths for each family.

	Constraints	Strengths
Market-based	Equity issues; time lags; vested interests; environmental impact	Improved resource allocation; no burden on the government budget
Interventionist	Costs; time lags	Direct support of sectors that matter for growth

Using the constraints

• Equity. Tax cuts give the largest gains to high earners, and lower benefits or no minimum wage hit low-income households.
• Time lags. Competition and incentives take time to change behaviour. Training and infrastructure take years to build and to pay back.
• Vested interests. Unions, protected firms and state employees may block reforms.
• Environmental impact. Deregulation and faster growth may raise pollution or resource use.
• Costs. Interventionist policies need funding, through taxes, borrowing or cuts elsewhere, and money spent badly can crowd out better uses.

Using the strengths

Market-based policies can improve how resources are allocated, and most do not require extra spending. Interventionist policies can direct support at sectors that are important for growth where markets alone might under-invest.

Judging growth, unemployment and inflation

The guide asks for strengths and limitations in promoting growth, low unemployment and low and stable inflation. A balanced answer says which objective each policy serves and how fast. For example, a training programme helps structural unemployment and growth in the long run, but does little for a cyclical downturn. An income tax cut may promote growth through incentives yet raise AD and inflation in the short run. Finish with a judgement that depends on the country, the time horizon and the size of any lag.

Common errors

• Shifting AD instead of LRAS in Diagram 1. Supply-side policy shifts LRAS.
• Drawing the minimum wage below equilibrium, where it has no effect.
• Treating every tax cut as costless. It can reduce revenue.
• Listing constraints without saying which policy they apply to.

Next steps

Revise with the revision notes and test yourself with the practice questions. The earlier demand and supply guide helps with the labour market diagram, and the macroeconomics measuring and managing the economy page covers wider Unit 3 context. For advice on writing answers, see exam preparation.

Official syllabus

IB Diploma Programme Economics guide, first assessment 2022, published February 2020 by the International Baccalaureate Organization. Sub-topic 3.7, Supply-side policies, in Unit 3 Macroeconomics.