A Level Economics: Government Microeconomic Intervention — Revision Notes

Condensed for the final weeks. For the full explanation, use the Government Microeconomic Intervention study guide.

3.1 Three reasons for intervention

Reason	Example
Public goods not provided at all	Street lighting, national defence (non-excludable, non-rival)
Merit/demerit goods mispriced	Too much demerit (cigarettes); too little merit (healthcare)
Undesirable market prices	Too high (harms consumers) or too low (harms producers)

3.2 Six tools — know the diagram effect for each

Tool	Diagram effect
Indirect tax	Supply shifts left → price ↑, quantity ↓
Subsidy	Supply shifts right → price ↓, quantity ↑
Direct provision	Bypasses the market entirely
Maximum price (below equilibrium)	Shortage
Minimum price (above equilibrium)	Surplus
Buffer stock	Buy low/store, sell high/release — stabilises price
Information provision	No price shift — fixes decision-making, not price

Tax/subsidy incidence rule: the more inelastic side of the market (demand or supply) bears the larger share of a tax’s burden, or captures the larger share of a subsidy’s benefit. Apply this to a given elasticity scenario — don’t just state it as a rule.

3.3 Income and wealth inequality

	Income	Wealth
Type	Flow (received over time — wages, interest, dividends)	Stock (owned at a point in time — property, savings, shares)

Gini coefficient: interpret a given value/Lorenz curve — you do not need to calculate it.

Four named redistribution policies:

1. Minimum wage
2. Transfer payments (benefits, no exchange required)
3. Progressive income/inheritance/capital taxes
4. State provision of essential goods/services

Precision matters for evaluation: minimum wage targets low earned income directly; progressive taxation and transfer payments redistribute after income/wealth has already been generated.

How the three sub-topics connect

3.1 (why) → 3.2 (tools for one market) → 3.3 (economy-wide distribution). A strong answer moves between levels: a minimum price (3.2) might be justified by merit-good under-consumption (3.1), but alone doesn’t fix the underlying income/wealth distribution (3.3) limiting some consumers’ ability to buy that good.

Worked example: tax incidence

A government imposes an indirect tax on a good where demand is price inelastic and supply is relatively elastic.

Rule:        The more inelastic side bears the larger tax burden.
Application: Demand is the inelastic side here, so consumers bear
             the larger share of the tax burden -- the price they
             pay rises by more than producers' effective revenue
             falls, because consumers cannot easily reduce quantity
             demanded in response to the price rise.

Diagram practice: the recurring exam format

Diagram-based questions on Topic 3.2 are common, and the specific direction of each shift is easy to get backwards without repeated practice. For each of the six tools, practise sketching the demand and supply diagram and labelling exactly which curve moves and in which direction:

Indirect tax:   Supply curve shifts LEFT (cost of supply rises)
Subsidy:        Supply curve shifts RIGHT (cost of supply falls)
Maximum price:  A horizontal line drawn BELOW the equilibrium price
                -- the gap between quantity demanded and quantity
                supplied at that price is the shortage
Minimum price:  A horizontal line drawn ABOVE the equilibrium price
                -- the gap is the surplus

Buffer stocks and information provision do not fit this simple shift-the-curve pattern – buffer stocks work by an external agency actively buying and selling stock to keep price within a target range, while information provision works by correcting the assumptions behind consumer/producer decision-making rather than moving either curve directly.

Exam traps

• Getting shortage vs surplus backwards for maximum vs minimum prices — maximum (below equilibrium) causes shortage; minimum (above equilibrium) causes surplus.
• Stating the tax-incidence rule without applying it to the specific elasticity scenario given.
• Confusing income (flow) with wealth (stock), or vice versa.
• Listing redistribution policies without linking each to the specific problem it addresses.
• Treating buffer stocks as identical to subsidies, rather than recognising the buy-low/sell-high stabilisation mechanism is distinct.

Government failure: the counterweight to intervention

Every tool in 3.2 can also fail to achieve its aim, and examiners reward answers that weigh this against the intended benefit rather than assuming intervention automatically improves the outcome:

Cause of government failure	Example
Imperfect information	Setting a subsidy at the wrong level because the true cost of production is unknown
Administrative cost	The cost of running a buffer stock scheme may exceed the stability benefit it delivers
Unintended consequences	A minimum price causing a persistent surplus that has to be stored or destroyed
Political self-interest	Policies chosen for short-term popularity rather than long-term economic benefit

A full evaluation of any single tool from 3.2 – not just buffer stocks – should weigh its intended correction against at least one plausible government-failure risk specific to that tool, rather than treating government intervention as costless by default.

Worked example: evaluating a minimum price policy

A government sets a minimum price for an agricultural good above the market equilibrium, aiming to protect farmers’ incomes.

Intended effect:  Price floor above equilibrium guarantees farmers a
                   higher, more stable price than the market alone
                   would provide.
Diagram effect:    Quantity supplied at the minimum price exceeds
                   quantity demanded, creating a surplus.
Government-failure
risk:              The government (or an agency) typically must buy
                   and store the surplus, creating an ongoing cost
                   that could exceed the value of the income support
                   provided to farmers -- turning an intended benefit
                   into a net cost if not carefully managed.

This intended-effect / diagram-effect / government-failure-risk structure applies to every tool in the table above, not only minimum prices, and is the reasoning shape “evaluate” questions on Topic 3.2 consistently reward.

Self-test

1. Name the three reasons for government intervention in 3.1.
2. What diagram effect does a maximum price below equilibrium cause, and why?
3. State the tax/subsidy incidence rule.
4. What’s the key distinction between income and wealth?
5. Name the four redistribution policies and one specific problem each addresses.

Answers: 1. Non-provision of public goods, over/under-consumption of demerit/merit goods, undesirable market prices. 2. A shortage — because the legal price cap sits below the market equilibrium price, quantity demanded exceeds quantity supplied at that price. 3. The more inelastic side of the market bears the larger share of a tax’s burden, or captures the larger share of a subsidy’s benefit. 4. Income is a flow (received over time); wealth is a stock (owned at a point in time). 5. Minimum wage (low earned income), transfer payments (income gaps without requiring work), progressive taxes (post-generation redistribution), state provision (access to essential goods/services regardless of income).