Cambridge A Level Economics: Monetary policy and supply-side policy (9708) – Revision Notes

These notes condense sections 5.3 (Monetary policy) and 5.4 (Supply-side policy) of the Cambridge International AS & A Level Economics 9708 syllabus for examination in 2026, 2027 and 2028. Topic 5 is AS Level content, and the syllabus treats it as assumed knowledge for A Level Papers 3 and 4. Full explanations are in the study guide. Test yourself with the practice questions, then check the course hub, the printable checklist and the free 10-minute diagnostics. All countries and figures are invented.

Key definitions

Term	Meaning
Monetary policy (5.3.1)	Changes by the government or central bank to interest rates, the money supply or credit regulations, aimed at aggregate demand and macroeconomic objectives
Expansionary monetary policy	Lower interest rates, more money, looser credit rules: AD shifts right
Contractionary monetary policy	Higher interest rates, less money, tighter credit rules: AD shifts left
Real interest rate	Nominal rate minus inflation rate (approximately)
Supply-side policy (5.4.1)	Policy that raises the economy’s capacity to produce, shifting the LRAS curve right
Productivity	Output per worker (or per unit of input)
Productive capacity	The maximum output the economy can produce with its resources

Monetary policy at a glance (5.3.2 to 5.3.3)

Tool	Expansionary	Contractionary	Main channel to AD
Interest rates	Cut	Raise	Consumption (borrowing and saving) and investment
Money supply	Increase	Reduce	Lower or higher interest rates, more or less bank lending
Credit regulations	Relax (higher loan-to-value cap)	Tighten (lower cap)	Fewer or more people can borrow

Chain of reasoning: a rate cut

1. The central bank cuts the policy rate.
2. Bank lending rates fall, so borrowing is cheaper and saving is less rewarding.
3. Households spend more and firms invest in more projects.
4. Consumption (C) and investment (I) rise, so AD shifts right.
5. Real output, the price level and employment rise (if there is spare capacity).

Reverse every step for a rate rise.

Method boxes

Interest cost. Interest = loan x rate. Compare the old and new bills.

Real interest rate. Real rate = nominal rate - inflation rate. Example: 5.5% - 2.0% = 3.5%.

Loan-to-value. Maximum loan = price x cap. Deposit = price - loan. Example: price 400,000 cu, cap 85%, loan 340,000 cu, deposit 60,000 cu.

Money market. Draw demand for money sloping down and supply vertical. A rise in supply moves the equilibrium rate down. Example: demand L = 480 - 30r. A supply of 330 gives r = 5%. A supply of 360 gives r = 4%.

New AD/AS equilibrium. Set AD equal to SRAS, solve for P, then substitute to find Y. Always give the percentage change in each variable.

AD/AS analysis (5.3.4 and 5.4.4)

Policy	Curve that moves	Real output	Price level	Employment
Expansionary monetary	AD right	Up	Up	Up
Contractionary monetary	AD left	Down	Down (or rises more slowly)	Down
Supply-side	LRAS right (and often SRAS right)	Up	Down (or rises more slowly)	Up

Label axes as price level and real output. Name each curve (AD1, AD2, SRAS, LRAS) and each equilibrium.

Worked reminder. Country R: AD is Y = 900 - 2P and SRAS is Y = 300 + 4P.

• Equilibrium: 6P = 600, so P = 100 and Y = 700.
• Expansionary policy raises AD by 60: Y = 960 - 2P. Then 6P = 660, so P = 110 and Y = 740.
• Output is up 5.7% (40 / 700) and the price level is up 10% (10 / 100).

When there is little spare capacity, the price rise is a larger share of the effect.

Supply-side policy (5.4.2 and 5.4.3)

Objectives: raise productivity and raise productive capacity.

Tool	How it works	Example of effect
Training and education	Raises the skill and output of labour	4 m of 25 m workers gain 10%: output per worker up 1.6%
Infrastructure development	Cuts travel time and costs, links markets	Travel falls from 25 to 15 minutes: 12 deliveries a day become 16
Support for technological improvement	Subsidies or grants lower the cost of research and investment	A 30% subsidy on 500,000 cu of research: the firm pays 350,000 cu

Other valid measures include better health care, tax incentives for investment and lower barriers for new firms. Each must be linked to productivity or capacity to earn credit.

Chain of reasoning: a training programme

1. Government funds training.
2. Workers’ skills improve, so output per worker rises.
3. Unit costs fall, so SRAS shifts right.
4. Capacity increases, so LRAS shifts right.
5. Potential output rises, the price level is lower than it would be, and employment can rise.

Worked reminder (supply-side). Country R again: AD is Y = 900 - 2P. After a supply-side policy lowers costs, SRAS moves from Y = 300 + 4P to Y = 360 + 4P.

• New equilibrium: 6P = 540, so P = 90 and Y = 720.
• Output is up 20 (2.9%) and the price level is down 10 (10%).
• Contrast with the expansionary case above, where both rose.

Percentage change in capacity

If full-capacity output rises from 800 to 840 cu bn, the increase is 40 / 800 = 5%.

Answering a policy question

1. Name the policy and the tool or measure.
2. Say which curve moves (AD, SRAS or LRAS) and in which direction.
3. State what happens to output, prices and jobs, using numbers if the question gives any.
4. Add a reason why the effect may be weaker, slower or stronger than expected.
5. Finish with a judgement tied to the situation in the question.

Must-know distinctions

Monetary policy	Supply-side policy
Demand-side: shifts AD	Supply-side: shifts AS
Effect is usually quicker, but the price level rises when output rises	Effect is usually slower, but the price level falls when output rises
Changes spending	Changes capacity and costs
Rates and credit rules can be changed again	Spending on skills and roads cannot be undone

Also: a price-level change moves the economy along a curve, while a change in any other factor shifts the curve.

Evaluation bank

• Monetary: time lags, low confidence, spare capacity, fixed-rate debts, borrowers versus savers, demand-pull versus cost-push inflation.
• Supply-side: long time lags, high cost, uncertain take-up, needs demand to use the extra capacity.
• Judge by size, timing, cause of the problem and who gains and loses. End with a conclusion that depends on stated conditions.

Quick self-test

1. A nominal interest rate is 5.5% and inflation is 2.0%. What is the real rate?
2. A firm has an 80,000 cu interest-only loan. The rate falls from 7% to 4%. By how much does the annual interest bill change?
3. A house costs 400,000 cu and the loan-to-value cap is 85%. Find the maximum loan and minimum deposit.
4. Demand for money is L = 480 - 30r. The money supply rises from 330 to 360. What happens to the equilibrium interest rate?
5. Name the three tools of monetary policy in the syllabus.
6. In Country R above, what are P and Y after AD rises by 60 at every price?
7. A country has 6 million workers producing 210 bn cu. Find output per worker. If it rises 4%, find new total output with the same workforce.
8. Full-capacity output rises from 800 to 840. Find the percentage change.
9. State which curve moves first when a government funds a road-building programme to cut costs for firms.
10. Give two reasons expansionary monetary policy might fail to raise output.

Answers

1. 5.5 - 2.0 = 3.5%.
2. 80,000 x 0.07 = 5,600 and 80,000 x 0.04 = 3,200. The bill falls by 2,400 cu.
3. 400,000 x 0.85 = 340,000 cu loan, so the deposit is 60,000 cu.
4. At 330: 480 - 30r = 330 gives r = 5. At 360: r = 4. The rate falls from 5% to 4%.
5. Interest rates, money supply, credit regulations.
6. P = 110, Y = 740.
7. 210 bn / 6 m = 35,000 cu. At 36,400 per worker, output is 218.4 bn cu.
8. 40 / 800 = 5%.
9. SRAS shifts right as costs fall; the improvement in capacity then moves LRAS right.
10. Any two: low confidence, banks unwilling to lend, fixed-rate debts, time lags, no spare demand from abroad, cost-push causes.

Where marks are usually lost

• Writing “demand rises” without saying that AD shifts and which component changes.
• Mixing up the effect of a rate cut on savers (less incentive) and on borrowers (more spending).
• Drawing a shift of AD for a supply-side policy.
• Quoting percentage changes without showing the working.
• Stating the tools of monetary policy without explaining the chain to output, prices and jobs.
• Ignoring spare capacity when predicting the price effect.
• Giving an evaluation point with no reason, such as “time lags” with no explanation of why.
• Omitting a conclusion that answers the question set.

Official syllabus

Cambridge International AS & A Level Economics 9708, syllabus for examination in 2026, 2027 and 2028, version 2, published by Cambridge University Press & Assessment. These notes cover sections 5.3 and 5.4.