AQA A-Level Economics · Topic 1.3
Public Goods &
Information Failure
Two ways markets produce too little of what society needs
📘 20 slides + 8 questions
⏱ 25 min
🎯 Theme 1: Market Failure
Learning Objectives
By the end of this lesson you will be able to…
Define public goods using the characteristics of non-excludability and non-rivalry, and explain the free rider problem
Distinguish pure public goods from quasi-public goods and merit goods
Define asymmetric information and explain adverse selection and moral hazard
Apply the Thames Barrier and PPI mis-selling as real-world examples of these market failures
Public Goods
What is a Public Good?
Definition
A public good has two key properties: Non-excludable: once provided, it is impossible (or prohibitively expensive) to prevent anyone from consuming it — you cannot exclude non-payers. Non-rival: one person's consumption does not reduce the amount available for others — there is no opportunity cost of an additional user.
NON-RIVAL + NON-EXCLUDABLE → PURE PUBLIC GOOD
National defence, streetlighting, flood defences, BBC World Service. Private market CANNOT provide — free rider problem.
NON-RIVAL + EXCLUDABLE → CLUB GOOD (quasi-public)
Netflix, cable TV, toll roads. Can be provided privately with a subscription/fee.
RIVAL + NON-EXCLUDABLE → COMMON RESOURCE
Fish in the ocean, clean air, public parks (when uncrowded). Susceptible to the "tragedy of the commons."
RIVAL + EXCLUDABLE → PRIVATE GOOD
A sandwich, a car, a haircut. Normal goods the market provides efficiently.
Key exam point: The critical failure point is NON-EXCLUDABILITY. If you cannot charge people for a good (because they can access it for free regardless), no profit-maximising firm will provide it → government must intervene.
Public Goods
The Free Rider Problem
THE PROBLEM
Because non-excludable goods are available to all whether or not you pay, rational individuals have an incentive to "free ride" — consume the good without contributing to its cost. If everyone reasons this way, no one pays, no one provides the good, and everyone is worse off. Classic collective action failure.
THE EXAMPLE
National defence: you cannot opt out of being defended even if you refuse to pay taxes. This means you could free ride — enjoying protection while paying nothing. If the state couldn't tax everyone, people would free ride → defence would be massively under-funded. Only compulsory taxation and government provision resolves this.
THE SOLUTION
Government provides public goods funded by compulsory taxation. This prevents the free rider problem by forcing everyone to contribute. The efficiency question: how much to provide? Government must estimate social value via cost-benefit analysis, since there is no market price signal.
Real-World Application · UK Flood Defences
The Thames Barrier: A Public Good in Action
🌊 THE THAMES BARRIER
Opened in 1982, the Thames Barrier is a tidal surge barrier spanning 520m across the Thames at Woolwich. Since opening, it has been raised over 220 times, protecting central London from flooding. Without it, a severe tidal surge could flood 1.25 million homes and businesses, costing over £100bn in damage.
📊 WHY IT'S A PUBLIC GOOD
Non-excludable: every property in the flood zone is protected whether or not it pays — there is no way to exclude a building from flood protection. Non-rival: protecting one building doesn't reduce protection for others. No private firm could recover its £530m construction cost by charging users — the free rider problem makes private provision impossible.
💰 GOVERNMENT PROVISION
The UK government spends approximately £2.6bn/year on flood defences (2021–27 programme). The Environment Agency manages over 5,000km of flood defences. The cost-benefit ratio of flood defence is estimated at 8:1 — every £1 spent prevents £8 in flood damage. Without government provision, this massive positive net social value would not be captured.
📝 QUASI-PUBLIC GOOD NOTE
Some services look like public goods but can be made excludable with technology. Digital TV signals can be encrypted (from non-rival to excludable club good). Toll roads use barriers (non-rival road → excludable). These are quasi-public goods. The key exam question is always whether provision involves a market failure, not just whether it currently happens to be public.
Information Failure
What is Information Failure?
Definition
Information failure occurs when buyers and sellers do not have equal access to relevant information about a good or service. Two main types: Asymmetric information: one party knows more than the other (e.g. a doctor knows more about treatments than a patient; a used car seller knows more about the car's quality than the buyer). Imperfect information: both parties lack relevant information (e.g. uncertainty about future events, consumers unaware of health risks of a product).
ADVERSE SELECTION
The problem of asymmetric information BEFORE a transaction. Bad types (lemons) drive out good types. George Akerlof's "Market for Lemons" (1970 Nobel Prize): in used car markets, sellers know quality but buyers don't → buyers offer average price → good-quality sellers exit → market unravels. Insurance markets: high-risk people buy more insurance, but insurers can't tell → premiums rise → low-risk people drop out → death spiral.
MORAL HAZARD
The problem of asymmetric information AFTER a transaction. Once insured, people take more risk. Banks after 2008 bailouts: "too big to fail" → excessive risk-taking knowing government will bail them out. Car insurance holders driving less carefully. The insurer can't fully monitor behaviour → over-provision of risky activity.
Information Failure · PPI Mis-selling
Akerlof's Market for Lemons & PPI
THE CONCEPT
George Akerlof's 1970 paper "The Market for Lemons" modelled used car markets. Some used cars are "peaches" (high quality) and some are "lemons" (low quality). The seller knows which; the buyer cannot tell. Buyers offer only the average price. Peach owners won't sell at average price. Lemons remain. As lemons flood the market, average quality falls, buyers lower bids further → market collapses. Nobel Prize in Economics 2001.
PPI APPLICATION
PPI mis-selling was a classic adverse selection / asymmetric information failure: banks knew PPI often wouldn't pay out for most customers (pre-existing conditions, self-employed, short-term workers all excluded). Customers didn't. Banks exploited this to sell overpriced, often-worthless insurance. 70–80% of premiums were commissions to banks. Result: 64 million policies mis-sold; £38.3bn in compensation (2011–2019).
SOLUTIONS
Market solutions: reputation systems, warranties, third-party certification (RAC inspection on used cars).
Government solutions: mandatory disclosure rules (FCA rules on financial products), consumer protection laws, licensing (doctors, lawyers must be qualified), information campaigns. The FCA's post-PPI rules require clearer product disclosure — a regulatory response to information failure.
Information Failure · Merit & Demerit Goods
Merit Goods and Demerit Goods
MERIT GOODS
Goods society believes are under-consumed relative to their social optimum — often because consumers underestimate long-run private benefits OR because positive externalities are ignored. Examples: education, healthcare, gym membership, pensions. Government response: subsidise or provide free (NHS, state schools). Note: merit goods are partly a value judgement — the government is making a paternalistic decision that people consume too little.
DEMERIT GOODS
Goods society believes are over-consumed — consumers underestimate harmful effects OR negative externalities. Examples: tobacco, alcohol, junk food. Government response: tax (excise duties), regulation (advertising bans), information campaigns. Demerit good = market would provide at Qm; social optimum = lower Q*. Closely related to negative externalities.
Exam distinction: A demerit good involves imperfect information (consumers don't fully understand the harm to THEMSELVES) AND/OR negative externalities (harm to others). If it's ONLY externalities: negative externality, not a demerit good. If it's ONLY imperfect consumer information: information failure/demerit good, not externality.
Policy Responses
Government Responses to Information Failure
MANDATORY DISCLOSURE
Require sellers to provide information buyers need. FCA's Key Facts Documents for financial products. Food labelling (calorie counts, allergens). Health warnings on cigarettes. Addresses asymmetric information by forcing the informed party to share.
LICENSING / REGULATION
Only allow licensed professionals to provide services where information asymmetry is severe. Medical licensing, financial adviser authorisation, food hygiene certificates. Prevents low-quality "lemons" from operating, raising average quality.
PROVISION OF INFORMATION
Government campaigns to correct imperfect information: anti-smoking ads, NHS "Change4Life" nutrition campaigns, financial education in schools. Works when consumers simply lack information (imperfect information), rather than when sellers actively exploit asymmetry.
CONSUMER PROTECTION LAW
UK Consumer Rights Act 2015, FCA redress schemes. After-the-fact remedies for information failure: if sold a lemon, you get a refund. The PPI compensation scheme paid £38.3bn — but this reactive approach is less efficient than preventing information failure in the first place.
Evaluation
Evaluating Public Goods & Information Failure
Strengths of the Theory
- Public goods theory explains precisely why some socially valuable goods are under-provided — and the free rider problem is a genuine, measurable market failure
- Non-excludability/non-rivalry framework clearly identifies when government provision is justified
- Information failure theory (Akerlof, Stiglitz, Spence — all Nobel laureates) explains financial mis-selling, insurance market failures, and healthcare market failure
- PPI redress shows that information failure can cause vast, quantifiable harm (£38.3bn) that regulation should prevent
Limitations & Counter-arguments
- The boundary between public goods and quasi-public goods is blurry — technology (digital encryption, GPS tolling) can make formerly non-excludable goods excludable
- Government provision of public goods does not guarantee efficiency — the amount provided is politically determined, not based on MC = MB analysis
- Paternalism in merit/demerit goods is controversial — who decides what consumers "should" consume? Government may have its own information failures
- Mandatory disclosure rules may be ineffective if consumers lack the financial literacy to understand complex documents (e.g. PPI terms were technically disclosed, just incomprehensible)
Essay Tip: The strongest evaluation for information failure: disclosure rules only work if consumers can understand the information disclosed. The PPI scandal occurred partly because documents were technically compliant but practically incomprehensible. This suggests education and financial literacy programmes may be more effective than disclosure alone.
Glossary
Key Terms
Public Good
Good that is non-excludable AND non-rival. The free rider problem prevents private provision. Must be provided by government funded by taxation.
Non-Excludable
Once provided, it is impossible to prevent non-payers from consuming the good — there is no way to exclude free riders.
Non-Rival
One person's consumption does not reduce availability for others. Zero marginal cost of an additional user.
Free Rider Problem
The incentive to consume a non-excludable good without paying for it, leading to under-provision if left to private markets.
Asymmetric Information
One party to a transaction has more relevant information than the other. Causes adverse selection (before) and moral hazard (after).
Adverse Selection
A market failure where asymmetric information causes bad quality (high risk/low quality) products or buyers to dominate, as the informed party exploits the uninformed. Akerlof's market for lemons.
Question 1 of 8 · Public Goods & Information Failure
Which combination of characteristics defines a pure public good?
B
Non-rival and non-excludable
C
Non-rival and excludable
D
Rival and non-excludable
Answer · Question 1
Which combination of characteristics defines a pure public good?
B
Non-rival and non-excludable
C
Non-rival and excludable
D
Rival and non-excludable
Correct: B. A pure public good is BOTH non-rival (one person's consumption doesn't reduce availability for others) AND non-excludable (impossible to prevent non-payers from consuming). Both conditions must hold. Non-rival + excludable = club good (Netflix). Rival + non-excludable = common resource (fish stocks).
Question 2 of 8 · Public Goods & Information Failure
Why does the free rider problem prevent private provision of flood defences?
A
Flood defences are too expensive to build without government funding
B
Private firms cannot exclude those who don't pay from receiving the protection
C
There is no demand for flood defences from consumers
D
Flood defences have very inelastic supply
Answer · Question 2
Why does the free rider problem prevent private provision of flood defences?
A
Flood defences are too expensive to build without government funding
B
Private firms cannot exclude those who don't pay from receiving the protection
C
There is no demand for flood defences from consumers
D
Flood defences have very inelastic supply
Correct: B. The key is non-excludability. No matter how a private firm prices flood defences, protected properties benefit whether they pay or not — exclusion is physically impossible. Rational property owners free ride. If everyone free rides, no firm earns revenue and flood defences are not built. Government resolves this through compulsory taxation.
Question 3 of 8 · Public Goods & Information Failure
The Thames Barrier has closed over 220 times since 1982, protecting London from tidal surges. Which statement best applies?
A
It is a merit good because consumers underestimate its benefits
B
It is a private good because only London residents benefit
C
It is a public good — non-rival protection that cannot exclude any property in the flood zone
D
It is a club good because only taxpayers benefit
Answer · Question 3
The Thames Barrier has closed over 220 times since 1982, protecting London from tidal surges. Which statement best applies?
A
It is a merit good because consumers underestimate its benefits
B
It is a private good because only London residents benefit
C
It is a public good — non-rival protection that cannot exclude any property in the flood zone
D
It is a club good because only taxpayers benefit
Correct: C. The Thames Barrier is non-rival (protecting one building doesn't reduce protection for others) and non-excludable (every property in the flood plain is protected regardless of contribution). This is a public good requiring government provision. It is not a merit good (which involves consumer information failure, not non-excludability).
Question 4 of 8 · Public Goods & Information Failure
George Akerlof's 'Market for Lemons' theory predicts that in used car markets with asymmetric information:
A
High-quality car sellers dominate because buyers trust reputable dealers
B
All cars sell at their true value as buyers research thoroughly
C
Low-quality cars ('lemons') tend to drive out high-quality cars because buyers can't distinguish quality
D
Prices fall to zero as buyers refuse to purchase any car
Answer · Question 4
George Akerlof's 'Market for Lemons' theory predicts that in used car markets with asymmetric information:
A
High-quality car sellers dominate because buyers trust reputable dealers
B
All cars sell at their true value as buyers research thoroughly
C
Low-quality cars ('lemons') tend to drive out high-quality cars because buyers can't distinguish quality
D
Prices fall to zero as buyers refuse to purchase any car
Correct: C. Buyers, unable to distinguish quality, offer only the average price. Owners of high-quality cars ("peaches") refuse to sell at the average — the price doesn't reflect their car's true value. Only lemon owners accept the average price. Market quality deteriorates, buyers lower bids further, and the market may collapse entirely. The solution: third-party inspection, warranties, or dealer reputation systems that credibly signal quality.
Question 5 of 8 · Public Goods & Information Failure
PPI mis-selling is primarily an example of:
A
A negative production externality — banks impose costs on third parties
B
A public good failure — PPI was non-excludable
C
Asymmetric information — banks knew PPI was often worthless to buyers but exploited this gap
D
A positive consumption externality — PPI provided benefits beyond the buyer
Answer · Question 5
PPI mis-selling is primarily an example of:
A
A negative production externality — banks impose costs on third parties
B
A public good failure — PPI was non-excludable
C
Asymmetric information — banks knew PPI was often worthless to buyers but exploited this gap
D
A positive consumption externality — PPI provided benefits beyond the buyer
Correct: C. PPI mis-selling was driven by asymmetric information: banks (sellers) had detailed knowledge of exclusion clauses, claim rejection rates, and commission structures that customers lacked. Banks exploited this informational advantage to sell overpriced, often-worthless insurance. The £38.3bn in compensation represents the scale of the welfare loss from this information failure.
Question 6 of 8 · Public Goods & Information Failure
Which best distinguishes a demerit good from a good with a negative externality?
A
Demerit goods always have perfectly inelastic demand; negative externalities don't
B
A demerit good involves consumers underestimating harm to themselves; a negative externality involves harm to third parties
C
Negative externalities are always more harmful than demerit goods
D
Demerit goods are always illegal; negative externalities involve legal products only
Answer · Question 6
Which best distinguishes a demerit good from a good with a negative externality?
A
Demerit goods always have perfectly inelastic demand; negative externalities don't
B
A demerit good involves consumers underestimating harm to themselves; a negative externality involves harm to third parties
C
Negative externalities are always more harmful than demerit goods
D
Demerit goods are always illegal; negative externalities involve legal products only
Correct: B. The distinction is who bears the cost: demerit goods (cigarettes, junk food) involve information failure where consumers underestimate harm to themselves (imperfect information). Negative externalities involve costs imposed on third parties not in the transaction. In practice, many goods are both (cigarettes: demerit good for the smoker AND negative externality via passive smoking), but the theoretical distinction is important for identifying the correct policy response.
Question 7 of 8 · Public Goods & Information Failure
Moral hazard occurs when:
A
Buyers purchase low-quality goods without knowing their quality (before the transaction)
B
One party takes greater risks after a transaction because they no longer bear the full cost of those risks
C
Government provides too much of a public good
D
Firms collude to exploit information asymmetry with consumers
Answer · Question 7
Moral hazard occurs when:
A
Buyers purchase low-quality goods without knowing their quality (before the transaction)
B
One party takes greater risks after a transaction because they no longer bear the full cost of those risks
C
Government provides too much of a public good
D
Firms collude to exploit information asymmetry with consumers
Correct: B. Moral hazard is the post-transaction problem of asymmetric information: once insured (or bailed out), the insured party takes more risk because the cost of failure falls on the insurer. Car insurance holders may drive more carelessly; banks deemed "too big to fail" may take excessive risks knowing taxpayers will absorb losses. Unlike adverse selection (pre-transaction), moral hazard occurs after the contract is signed.
Question 8 of 8 · Public Goods & Information Failure
Which government policy most directly addresses adverse selection in financial markets?
A
A Pigouvian tax on risky financial products
B
Mandatory disclosure rules requiring financial firms to clearly explain product terms and risks
C
A price ceiling on financial product fees
D
Nationalising all financial institutions to eliminate profit motive
Answer · Question 8
Which government policy most directly addresses adverse selection in financial markets?
A
A Pigouvian tax on risky financial products
B
Mandatory disclosure rules requiring financial firms to clearly explain product terms and risks
C
A price ceiling on financial product fees
D
Nationalising all financial institutions to eliminate profit motive
Correct: B. Adverse selection in financial markets (like PPI) occurs because sellers know more than buyers about product quality. Mandatory disclosure — requiring sellers to clearly explain terms, exclusions, and charges — reduces the information gap and enables buyers to make informed decisions. The FCA introduced stricter disclosure requirements post-PPI scandal. Note: disclosure only works if the information is comprehensible — a key exam evaluation point.
End of Lesson
Well done! Topic 1.3 complete.
You've covered public goods, the free rider problem, asymmetric information, adverse selection, moral hazard, merit and demerit goods, and government responses.
KEY EXAMPLES TO RECALL
Thames Barrier (public good · non-excludable, non-rival, £2.6bn/yr, 8:1 cost-benefit) · PPI mis-selling (asymmetric info · 64m policies · £38.3bn compensation)
NEXT STEPS
Practice 25-mark essays on public goods and information failure. Link to externalities (Topic 1.2) and government failure (Topic 1.4).