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Market Failure and Government Intervention
Exam Board: AQA Pearson Edexcel OCR WJEC / Eduqas CCEA
📌 Key Points
Key Fact: Externalities: divergence private/social costs/benefits; Negative: MSC>MPC (pollution); Positive: MSB>MPB (education)
Key Fact: Pigouvian tax = MEC at optimum; Subsidy = MEB; Tradable permits: cap-and-trade; Regulation: standards/bans
Key Fact: Public goods: non-excludable (can't stop use), non-rival (one's use doesn't reduce other's) -> free rider -> underprovision
Key Fact: Info asymmetry: adverse selection (pre-contract, hidden info), moral hazard (post-contract, hidden action); Solutions: signalling, screening, regulation
Key Fact: Competition: CMA investigates mergers (SLC test), cartels (price-fixing), abuse of dominance; Regulation: price caps (RPI-X), profit caps
🎯 Learning Objectives
Identify sources of market failure: externalities, public goods, information asymmetry, market power Analyse negative/positive externalities: MSC=MPC+MEC, MSB=MPB+MEB Evaluate policies: Pigouvian taxes, subsidies, tradable permits, regulation, nudges Understand public goods: non-excludable, non-rival; free-rider problem Analyse information asymmetry: adverse selection, moral hazard; solutions Evaluate competition policy: monopolies, mergers, cartels, regulation
💡 Worked Example
Exam-Style Question
Question: A factory pollutes a river. MPC = 20+Q, MEC = 5, MPB = 100-Q. Find market output, social optimum, and tax
Model Answer:
Market: MPC=MPB -> 20+Q=100-Q -> Q=40. Social: MSC=MSB -> 20+Q+5=100-Q -> 2Q=75 -> Q=37.5. Tax = MEC = 5 per unit. At Q=37.5, P=100-37.5=62.5. Tax revenue = 5x37.5=187.5
❓ Practice Questions
Questions:
Why is clean air a public good? Draw MSC/MPC for negative externality Explain adverse selection in insurance Evaluate tradable permits vs carbon tax Why regulate natural monopolies?
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