Public Goods & Information Gaps

The free rider problem, non-rivalry, non-excludability — and how information failure causes markets to misallocate resources

SPEC 1.3 • MARKET FAILURE

The Four Types of Market Failure

Externalities are the most tested market failure — but the specification requires you to understand all four causes. This lesson covers the remaining two: public goods and information gaps.

Type of Market FailureCore ProblemLesson

ExternalitiesSpillover costs/benefits not priced — MSC ≠ MPC or MSB ≠ MPBLesson 1.08 ✓

Public goodsNon-rival + non-excludable → free rider → market won't provideThis lesson ←

Information gapsAsymmetric / insufficient information → irrational decisions → misallocationThis lesson ←

Factor immobilityGeographical / occupational immobility → structural unemploymentThis lesson (brief)

Exam Tip

Exam questions often ask you to identify and explain a specific type of market failure. Make sure you can distinguish clearly between all four — examiners penalise vague or mixed-up explanations.

Public Goods — The Two Criteria

Definition — Public Good

A public good is a good that is simultaneously non-rival AND non-excludable. Both criteria must be present — a good with only one property is not a pure public good.

Non-Rival

Consumption by one person does not reduce the quantity or quality available to others — there is no congestion effect. One person "using" national defence does not reduce the defence available to their neighbour.

Non-Excludable

It is impossible to prevent people from consuming the good, even if they have not paid for it. Once national defence is provided, every resident benefits — there is no technical mechanism to exclude non-payers.

Key Examples

Pure public goods: national defence, street lighting, public fireworks displays, flood defences, the justice system, lighthouses.

Test: Ask — (1) if one more person consumes it, does availability fall? (Non-rival = no.) (2) Can non-payers be excluded? (Non-excludable = no.) If both answers are "no" → it is a public good.

The Free Rider Problem

Definition

The free rider problem occurs when individuals can benefit from a public good without paying for it — because the good is non-excludable. This leads to under-provision or complete non-provision by the private sector.

Since non-payers cannot be excluded, a private firm cannot generate revenue by charging for the good — rational consumers will free ride and wait for someone else to pay.

Good is non-excludable — no mechanism to charge non-payers

Rational consumers free ride — wait for others to provide it

Private firms cannot recover costs → no profit motive to produce

Market provides zero or far less than the social optimum

Market failure — government must provide via taxation

Exam Tip — How to Score Full Marks

Always link the free rider problem explicitly back to non-excludability. It is non-excludability — not non-rivalry — that directly causes the free rider problem and hence market failure. Non-rivalry alone does not prevent charging.

Why Markets Fail to Provide Public Goods

Private goods: supply and demand determines an equilibrium — the market works. Public goods: non-excludability means no private firm can recover its costs — the supply curve never materialises. Government must step in.

Quasi-Public Goods & the Public Good Trap

Definition — Quasi-Public Good

A quasi-public good is a good that has some characteristics of a public good but is not purely non-rival and non-excludable. It may become rival when congested, or excludable with technology.

GoodNon-Rival?Non-Excludable?Classification

National defence✓ Yes✓ YesPure public good

Street lighting✓ Yes✓ YesPure public good

Uncongested road✓ Yes (until congested)✗ Can be tolledQuasi-public good

NHS / Education✗ Rival (limited slots)✗ Can be excludedMerit good — NOT public good

Lighthouse✓ Yes✓ Hard to exclude shipsPure public good

Examiner Alert — The Most Common Error

Students consistently call healthcare and education "public goods". They are merit goods — they are rival (hospital beds are limited) and excludable (private schools exist). Using the wrong classification loses definition marks and chains of reasoning marks.

Information Gaps & Information Failure

Definition — Information Gap / Information Failure

Information failure occurs when consumers or producers lack sufficient information to make rational decisions, leading to a misallocation of resources. The market produces too much of some goods and too little of others.

Definition — Asymmetric Information

Asymmetric information occurs when one party in a transaction has more or better information than the other — creating an imbalance that causes market failure.

Why This Causes Market Failure

Rational decision-making requires full information. When consumers lack information about the true costs (demerit goods) or benefits (merit goods) of their choices, they over- or under-consume relative to the social optimum — even without any externality being present.

Asymmetric Information — Three Classic Cases

Used Car Market — "Market for Lemons"

Who knows more: Seller knows the car's quality; buyer does not.

Result (Akerlof, 1970): Buyers assume average quality → only willing to pay average price → owners of high-quality cars withdraw → average quality falls → market may collapse entirely. Only "lemons" (low quality) remain.

Insurance — Moral Hazard & Adverse Selection

Moral hazard: Once insured, policyholders take more risks — insurer cannot observe behaviour.

Adverse selection: High-risk individuals are more likely to buy insurance → insurer misprices risk → unsustainable premiums for low-risk individuals.

Healthcare

Who knows more: Doctors have superior clinical knowledge; patients cannot verify diagnoses or treatment necessity.

Result: Patients cannot make fully rational consumption decisions → may under-consume (don't seek treatment) or over-consume (follow every recommendation) → market fails to achieve optimal allocation.

Labour Market

Who knows more: Job applicants know their own productivity; employers cannot perfectly observe it before hiring.

Result: Employers may underpay all workers based on average productivity → high-productivity workers leave → quality of workforce declines (adverse selection in labour markets).

Merit & Demerit Goods — Information Failure

Merit Good

A good that is under-consumed in a free market because individuals underestimate its private benefit — or because of positive externalities. The market underprovides relative to the social optimum.

Examples: education, healthcare, exercise, pension saving.

Demerit Good

A good that is over-consumed in a free market because individuals overestimate its private benefit or ignore negative externalities. The market overproduces relative to the social optimum.

Examples: cigarettes, alcohol, gambling, junk food.

Distinction from Pure Externalities

Merit/demerit goods involve two simultaneous market failures: an externality AND an information gap. With a pure negative externality of production (e.g. factory pollution), consumers may be fully informed — the failure arises from spillover costs. With a demerit good (e.g. cigarettes), consumers also incorrectly assess their own private harm. The combined failure justifies stronger intervention.

Factor Immobility

Definition

Factor immobility is the inability of factors of production — particularly labour — to move quickly to where they are most productively employed, resulting in structural unemployment and productive inefficiency.

Geographical Immobility

Workers cannot or will not move to regions where labour demand is highest. Causes: high housing costs, family ties, language barriers, lack of information about vacancies.

Example: Long-term unemployment in former mining/manufacturing regions (South Wales, North East England) while vacancies persist in London.

Occupational Immobility

Workers lack the skills required for jobs in growing sectors. Causes: long retraining periods, age barriers, lack of transferable qualifications.

Example: Coal miners displaced by pit closures cannot easily reskill as software engineers — structural unemployment persists even when tech vacancies are abundant.

Policy Link

Factor immobility justifies supply-side policies: government retraining schemes (apprenticeships, T-Levels), housing policies to ease geographical mobility, and wage subsidies for employers taking on structurally unemployed workers.

Correcting Market Failures — Policy Responses

Market FailurePolicy ResponseHow It WorksLimitation

Public goods (free rider)State provision + taxationGovernment provides good funded by compulsory taxation — eliminates free rider problemDifficult to determine optimal level of provision; taxes may cause deadweight loss elsewhere

Asymmetric informationRegulation + information provisionMandatory disclosure laws (car history reports), product safety regulation, professional licensingRegulatory capture; government may also lack information; compliance costs

Merit goods (under-consumed)Subsidies; state provision; nudgesLower the private cost → raise effective MPB → move consumption toward social optimumOpportunity cost of spending; paternalism concerns; may subsidise those who would have consumed anyway

Demerit goods (over-consumed)Taxation; advertising bans; regulationRaise private cost → reduce consumption toward social optimum; restrict availabilityInelastic demand limits quantity effect; regressive taxation; black markets

Factor immobilityRetraining; housing policy; wage subsidiesRemove barriers to labour mobility; subsidise skill acquisition in growth sectorsLong time lags; retraining may not match employer needs; brain drain from regions

Worked Example — Cigarettes: Two Market Failures

Cigarettes involve both a demerit good (information failure) and a negative externality (consumption externality). Here is how to construct a Level 4 chain covering both causes:

Chain 1 — Demerit Good / Information Failure

Consumers underestimate the long-run private health damage of smoking→Perceived MPB > true MPB — market overconsumption relative to own welfare→Information failure causes market to overallocate resources to cigarettes

Chain 2 — Negative Externality of Consumption

Second-hand smoke imposes external costs: NHS treatment, lost productivity, harm to non-smokers→MSB < MPB — social cost exceeds private cost→Market overproduces at Qm > Q* — deadweight welfare loss exists

AO1 Precision Point

In the essay, distinguish the two chains clearly: "Two separate market failures justify intervention. First, an information failure — consumers underestimate private harm. Second, a negative externality of consumption — external costs are not priced into market equilibrium."

Practice Question

(a) Define the term "public good". [2 marks]

(b) Explain, using a chain of reasoning, why the free rider problem means that the private sector will not provide national defence. [4 marks]

(c) Evaluate the view that information failure is the most significant cause of market failure in the market for healthcare. [12 marks]

a

A public good is a good that is non-rival (consumption by one person does not reduce availability to others) AND non-excludable (it is impossible to prevent people from consuming it even if they have not paid). [1 mark for each criterion — both required for 2 marks]

b

National defence is non-excludable — once provided, all citizens benefit regardless of whether they have paid. Rational individuals have an incentive to free ride — waiting for others to pay while benefiting at zero cost. Since a private firm cannot prevent free riders, it cannot generate revenue to cover costs. Therefore no private firm has a profit motive to supply national defence, and the market produces zero — the government must provide it through compulsory taxation. [Award 4 marks for fully linked 4-step chain referencing non-excludability, free riding, inability to charge, and non-provision.]

c

KAA — Information failure in healthcare: Patients cannot assess the quality or necessity of medical treatment (asymmetric information — doctors have superior knowledge). Patients may under-consume — failing to seek treatment for symptoms they cannot interpret — or over-consume — following all recommendations uncritically. This misallocation justifies government intervention: state provision (NHS), regulation of professional standards, and mandatory information disclosure. Counter-argument (evaluate): However, healthcare also generates positive externalities (healthy population raises productivity → MSB > MPB) — which is a separate, independent cause of market failure. Even if information were perfect, the positive externality would still justify subsidised provision. Additionally, factor immobility in the healthcare labour market creates supply constraints. AO4 Judgement: Information failure is a significant cause in healthcare — but it operates alongside positive externalities, not as the sole explanation. The relative importance depends on context: for preventive health decisions (vaccination, cancer screening) information failure dominates; for access to treatment, positive externalities and public good characteristics are equally significant.

AO4 Evaluation Toolkit

Eval Point 1 — Multiple Simultaneous Failures

"In most real-world markets, multiple types of market failure coexist. Healthcare involves positive externalities, asymmetric information, AND merit good characteristics. Intervention targeting only one failure may leave others uncorrected — a comprehensive policy package is required."

Eval Point 2 — Quasi-Public Goods and State Provision Level

"Not all goods with public characteristics require full state provision. Quasi-public goods (roads, parks) can be provided privately with tolls or entry charges — the extent of state involvement depends on the degree of non-excludability, not merely whether some free riding exists."

Eval Point 3 — Behavioural Economics Link

"Information provision alone may not correct information gaps if consumers exhibit present bias or bounded rationality. Even with full health warnings, smokers continue due to present bias — suggesting nudges (default opt-out of tobacco marketing) or stronger price intervention may be more effective than information campaigns alone."

Eval Point 4 — Government Failure Risk

"State provision of public goods and merit goods carries the risk of government failure — the government may not know the socially optimal quantity to provide, and political pressures may lead to over- or under-provision. There is also an opportunity cost: resources used for state provision cannot be used elsewhere."

Eval Point 5 — Technology and Excludability

"Advances in technology are making previously non-excludable goods excludable — digital encryption, GPS tolling, and paywalls mean that the class of pure public goods may be shrinking. This reduces the case for automatic state provision of some quasi-public goods."

Examiner Alerts — Common Errors

Alert 1 — Calling NHS/Education "Public Goods"

This is the single most common error in market failure questions. Healthcare and education are merit goods — they are rival (hospital beds are scarce) and excludable (private schools exist). The term "public good" has a precise economic definition: non-rival AND non-excludable. Using it loosely loses definition marks and chains of reasoning marks.

Alert 2 — Not Explaining the Free Rider Mechanism

Students often state "the private sector won't provide public goods" without explaining why. You must link: non-excludability → free riding → inability to generate revenue → no profit motive → non-provision. Skipping any link caps the answer at Level 2.

Alert 3 — Confusing Asymmetric Information with Information Gap

An information gap is the general problem of insufficient information. Asymmetric information is the specific case where one party knows more than the other. Both cause market failure but via different mechanisms — use the correct term for the context given in the question.

Alert 4 — Not Distinguishing Merit Good from Positive Externality

A positive externality is a spillover to third parties. A merit good failure arises because the consumer themselves undervalues the good. Both justify intervention but for different reasons. A question specifically about information failure requires you to focus on the consumer's own misperception — not the externality.

Summary

Key Definitions — Learn These Word for Word

TermExam-Ready Definition

Public goodA good that is non-rival (consumption by one does not reduce availability to others) AND non-excludable (impossible to prevent free riders) — both criteria required

Free rider problemWhere individuals can benefit from a public good without paying for it, leading to under-provision or non-provision by the private sector

Information failureWhen consumers or producers lack sufficient information to make rational decisions, leading to a misallocation of resources

Asymmetric informationWhen one party in a transaction has more or better information than the other — creating market failure

Merit goodA good that is under-consumed in a free market because individuals underestimate its private benefit (e.g. healthcare, education)

Demerit goodA good that is over-consumed in a free market because individuals overestimate its private benefit or ignore external costs (e.g. cigarettes, alcohol)

Free Rider Chain (Memorise)

Non-excludable → rational agents free ride → private firm can't charge → no revenue → no profit motive → market provides zero → government must provide via taxation

AO4 Judgement Template

"Information failure is [significant / less significant] in the market for [X] because [reason]. However, [positive externality / public good / demerit good characteristic] is equally/more important because [reason], suggesting a [combined policy / single intervention] is required."

Exam Tip

The most scoring answers link market failures together: "Cigarettes involve both an information failure (demerit good) and a negative externality of consumption. Policy must address both — information campaigns alone are insufficient if present bias prevents consumers from acting on the information provided."