How does a central bank use interest rates and the money supply to manage the economy?
Monetary policy, the role of the central bank, the use of interest rates and quantitative easing, the transmission mechanism, and the limitations of monetary policy.
An answer to AQA A-Level Economics 4.2.7, covering monetary policy and the role of the central bank, the use of interest rates and quantitative easing, the monetary transmission mechanism, and the limitations of monetary policy.
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What this dot point is asking
AQA wants you to explain monetary policy and the role of the central bank, the use of interest rates and quantitative easing, the transmission mechanism, and the limitations of monetary policy. The transmission chain and the evaluation of QE are common higher-tariff questions.
Monetary policy and the central bank
The central bank is operationally independent, meaning it chooses how to hit the target the government sets. Independence helps anchor inflation expectations, because markets and households trust that the bank will act to keep inflation near target rather than being swayed by short-term political pressure.
Interest rates and quantitative easing
The bank rate is the rate at which the central bank lends to commercial banks, which then feeds through to the rates households and firms pay. QE is an unconventional tool used when the bank rate hits its zero lower bound and cannot be cut further.
The transmission mechanism
A change in the bank rate affects the economy through several channels: the cost of borrowing and the return on saving (affecting consumption and investment, especially of houses, cars and capital goods), asset prices and wealth (lower rates raise house and share prices, boosting consumption via the wealth effect), business and consumer confidence, and the exchange rate (a rate cut tends to weaken the currency, boosting net exports). These channels combine to shift aggregate demand and, after a lag, the price level.
Limitations
Monetary policy faces several limits: time lags (changes can take up to two years to have their full effect, so the bank must act pre-emptively), the zero lower bound and the risk of a liquidity trap where very low rates fail to stimulate spending, dependence on confidence (low rates may not boost spending if households and firms are pessimistic or heavily indebted), the bluntness of a single national interest rate, and the concern that QE mainly inflates asset prices and worsens wealth inequality.
Exam-style practice questions
Practice questions written in the style of AQA exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AQA 20199 marksUsing an AD and AS diagram, analyse how a rise in the bank rate could reduce demand-pull inflation.Show worked answer →
A 9 mark analysis question rewards a developed transmission chain and a diagram.
- Mechanism
- A higher bank rate raises the cost of borrowing and the reward for saving, so consumption (especially credit-financed) and investment fall. It can also raise the exchange rate, cutting net exports.
- AD shift
- These channels reduce components of AD, shifting AD left.
- Outcome
- On the diagram, AD shifts left along AS, lowering the price level (or its rate of increase), easing demand-pull inflation, with some fall in output near capacity.
Markers reward the transmission channels, the leftward AD shift and the link to lower inflation, with an accurate diagram and a note on time lags.
AQA 20219 marksAssess the effectiveness of quantitative easing as a tool of monetary policy in a deep recession.Show worked answer →
A 9 mark assessment question needs both sides and a judgement.
- Case for
- When the bank rate is near the zero lower bound, QE injects money by buying assets, raising their prices, lowering long-term yields, easing credit, raising wealth and confidence, and shifting AD right.
- Case against
- It may mainly inflate asset prices, widening wealth inequality; banks may hoard reserves rather than lend; and its effect depends on confidence.
- Judgement
- QE can support demand when conventional policy is exhausted, but it is a blunt tool with distributional side effects and works best alongside fiscal policy. Markers reward weighing the channels against the limitations and a supported stance.
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Sources & how we know this
- AQA A-level Economics (7136) specification — AQA (2015)