What are public goods and why do they lead to market failure?

Public goods are goods that are non-excludable and non-rivalrous, meaning that individuals cannot be effectively excluded from use and one person's use does not reduce availability to others. This leads to market failure because private markets may not provide these goods efficiently, as there is little incentive for firms to produce them when they cannot charge users directly, resulting in under-provision or no provision at all.

How does the non-provision of public goods relate to market failure in the context of Edexcel International A Levels Economics?

In the Edexcel International A Levels Economics curriculum, the non-provision of public goods is a classic example of market failure. This occurs when the free market fails to allocate resources efficiently, leading to a loss of economic and social welfare. Public goods like national defense or street lighting are often underprovided by the market, necessitating government intervention to ensure they are available for public benefit.

Why can't private markets efficiently provide public goods?

Private markets struggle to provide public goods efficiently due to the free-rider problem. Since public goods are non-excludable, individuals can benefit from them without paying, leading to insufficient funding and provision by private firms. This results in market failure, as the market does not supply the socially optimal quantity of the good.

What role does government intervention play in addressing the non-provision of public goods?

Government intervention is crucial in addressing the non-provision of public goods. By funding and providing these goods directly, or through subsidies and regulations, governments can ensure that public goods are available to all, correcting the market failure. This intervention helps achieve a more efficient allocation of resources and improves overall social welfare.

Can you provide examples of public goods and explain their significance in economics?

Examples of public goods include national defense, public parks, and street lighting. These goods are significant in economics because they illustrate the challenges of non-excludability and non-rivalry, leading to market failure. Understanding public goods helps students of Edexcel International A Levels Economics grasp why government intervention is necessary to provide these goods and ensure they are available for the benefit of society as a whole.

Why is "Defining a public good as 'a good provided by the public sector / government'" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: The name 'public good' sounds like it means 'provided by the public sector', and the government does happen to provide many of them. How to avoid it: Define it by the TWO characteristics — non-rivalry AND non-excludability. The government provides public goods BECAUSE of those characteristics; the characteristics come first. This is the single most penalised error in the topic. Source: WEC11 Examiner Reports — recurring error

Why is "Confusing non-rivalry with non-excludability" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: The two terms sound similar and both describe 'public' features, so students blur them or use one to define the other. How to avoid it: Non-rivalry is about QUANTITY (consumption does not use the good up). Non-excludability is about PAYMENT (you cannot keep non-payers out). Keep them as two separate, clearly defined tests. Source: WEC11 Examiner Reports

Why is "Calling a merit good (e.g. education, healthcare) a public good" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: Both are often government-provided, so students lump them together. How to avoid it: A merit good (education, healthcare) is RIVAL and EXCLUDABLE — a private good that is under-consumed because of positive externalities/information gaps. A public good is non-rival and non-excludable. Government provision is not what makes a good 'public'. Source: WEC11 mark schemes

Why is "Treating every 'public' good as a pure public good" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: Students learn the two extremes (private vs pure public) and forget the middle case. How to avoid it: Remember quasi-public goods (roads, beaches, bridges): the characteristics hold only PARTIALLY — a road congests (becomes rival) and a toll makes it excludable. Naming quasi-public goods is a strong evaluation point. Source: WEC11 Examiner Reports

Why is "Describing the public-good problem as 'the market produces too little'" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: Students carry over the phrasing used for demerit goods or externalities (partial failure). How to avoid it: For a PURE public good the market produces essentially NOTHING — a MISSING market and COMPLETE market failure. Reserve 'too little / too much' for partial failure cases where a market does exist.

Why is "Explaining the free-rider problem as simply 'people are selfish and won't pay'" a common mistake in Non-provision of public goods - Market Failure?

Why it happens: Students grasp the outcome (no one pays) but skip the reasoning that produces it. How to avoid it: Link non-payment to NON-EXCLUDABILITY: because non-payers cannot be excluded, each consumer rationally waits to free-ride on others; since all do so, no one pays and no revenue is raised. The AO3 mark is in the chain, not the word 'selfish'. Source: WEC11 Examiner Reports

Edexcel International A Levels Economics (XEC11-YEC11)

Non-provision of public goods - Market Failure

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Short Notes - Non-provision of public goods - Market Failure

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Detailed Study Notes

Detailed notes on Markets in Action for Edexcel International A Levels Economics, covering key concepts, explanations, examples, and exam-focused revision points.

Non-provision of Public Goods — Edexcel IAL Economics (WEC11) Study Notes

A public good has two features — non-rivalry and non-excludability — that break the price mechanism. Because non-payers cannot be excluded, everyone free-rides, no firm can profit, and the market is missing: a case of complete market failure. Learn to classify goods, explain the free-rider problem step by step, and justify government provision — the exact AO1/AO3 skills examiners reward in Section B and Section C.

At a glance

A public good is defined by two characteristics: non-rivalry and non-excludability — it is NOT simply 'a good the government provides'.
Non-rivalry: one person's consumption does not reduce the amount available for others (e.g. one more person seeing a street light uses none of it up).
Non-excludability: once provided, you cannot stop non-payers from consuming it (e.g. you cannot switch off national defence for one household).
A private good is the opposite — rival AND excludable (e.g. a sandwich, a bus seat).
The free-rider problem: because non-payers cannot be excluded, each consumer waits for others to pay, so no one pays.
With no way to charge, the private sector cannot make a profit, so it under-provides or does not provide the good at all — a missing market (complete market failure).
This is why government provides public goods, funded through taxation (e.g. national defence, street lighting, flood defences).
Pure public goods are fully non-rival and non-excludable; quasi-public goods (e.g. roads, beaches) are only partially so.

What you’ll learn

Mapped to the Pearson Edexcel International A Levels XEC11-YEC11 syllabus (2020-2026).

1.3.5 — Understand the distinction between a public good and a private good using the characteristics of non-rivalry and non-excludability.
1.3.5 — Explain the free-rider problem and why it leads to the non-provision (or under-provision) of public goods by the private sector.
1.3.5 — Explain why the missing market for public goods is an example of market failure that justifies government provision.
1.3.5 — Distinguish between pure public goods and quasi-public goods, with examples.

The two characteristics of a public good

A public good is defined by two features — non-rivalry (using it does not use it up) and non-excludability (you cannot keep non-payers out) — not by who provides it.

A public good is a good that has two defining characteristics: it is non-rival and non-excludable. Master these two words — the whole subtopic is built on them, and the single most common exam error is to define a public good as 'a good provided by the public sector'. That is wrong: the definition is about the nature of the good, not who happens to supply it.

1. Non-rivalry. When one person consumes the good, it does not reduce the amount available for everyone else. The good is not 'used up'. When you walk under a street light, there is exactly as much light left for the next person — your consumption subtracts nothing from theirs. Contrast this with an apple: if you eat it, no one else can.

2. Non-excludability. Once the good is provided, it is impossible (or prohibitively expensive) to stop people who have not paid from consuming it. You cannot 'switch off' national defence for one household that refuses to pay its taxes, nor prevent a passing ship from seeing a lighthouse beam. There is no practical way to fence the good off and charge an entry price.

Classic examples of goods with both features are national defence, street lighting, flood defences, lighthouses and policing. Because both characteristics hold, the ordinary market cannot function normally — as the next sections show.

A* link. Keep the two words razor-sharp and don't confuse them. Non-rivalry is about quantity (consumption doesn't use the good up). Non-excludability is about payment (you can't keep non-payers out). A good can have one without the other — that is exactly what defines a quasi-public good later on.

A public good is defined by TWO characteristics: non-rivalry AND non-excludability.
Non-rivalry = one person's use does NOT reduce the amount left for others.
Non-excludability = you CANNOT prevent non-payers from consuming it.
It is NOT defined as 'a good the government provides' — that is the classic error.
Examples: national defence, street lighting, flood defences, lighthouses, policing.

See the full worked example for non-provision of public goods - market failure →

Private goods, public goods and the 2×2 classification

Goods can be rival or non-rival, and excludable or non-excludable. The four combinations give private, public, quasi-public (common) goods.

A private good is the mirror image of a public good: it is both rival and excludable. Most goods you buy are private — a sandwich, a cinema seat, a bus ticket. If you consume it, there is less (or none) for others (rivalry), and the seller can easily refuse to serve you unless you pay (excludability). Because sellers can charge, the price mechanism works and the private sector supplies these goods profitably.

We can lay out every possibility on a simple 2×2 table using the two characteristics:

	Excludable (can charge)	Non-excludable (cannot charge)
Rival (use it up)	Private good — e.g. a sandwich, a bus seat	Common resource — e.g. ocean fish stocks, a public grazing field
Non-rival (does not use up)	Quasi-public good — e.g. a toll road, satellite TV, a cinema	Pure public good — e.g. national defence, street lighting

The two corners that matter most for spec 1.3.5 are:

Private good (top-left): rival + excludable → the market supplies it normally.
Pure public good (bottom-right): non-rival + non-excludable → the market fails completely (the rest of this note explains why).

The other two boxes are useful for evaluation. A common resource (rival but non-excludable, e.g. fish in the open sea) is over-used because no one owns it — the classic 'tragedy of the commons'. A quasi-public good sits between private and public: it has some of each characteristic, which is why it can sometimes be charged for even though it looks public.

Private good = RIVAL + EXCLUDABLE (e.g. sandwich, bus seat) → market supplies it.
Pure public good = NON-RIVAL + NON-EXCLUDABLE (e.g. defence) → market fails.
Common resource = rival but non-excludable (e.g. ocean fish) → over-used.
Quasi-public good = partly non-rival / non-excludable (e.g. toll road) → in between.
The 2×2 grid (rival × excludable) is the fastest way to classify any good.

See the full worked example for non-provision of public goods - market failure →

The free-rider problem

Because non-payers cannot be excluded, every consumer waits for someone else to pay — so no one pays, and no firm can earn revenue.

The free-rider problem is the reason a public good breaks the market. A free rider is someone who consumes a good without paying for it, because the good's non-excludability means they cannot be stopped.

Trace the logic slowly:

Suppose a firm tries to sell a public good — say, it offers to install street lighting on your road if residents each pay £50.
Because the good is non-excludable, once the lights are on everyone benefits, whether or not they paid.
Because it is non-rival, your neighbour enjoying the light takes nothing away from you.
So each rational resident reasons: 'If I don't pay, I'll still get the light once others pay — so why pay?'
But everyone reasons the same way, so no one pays. Each waits to free-ride on the others.
With no one willing to pay, the firm collects no revenue, cannot cover its costs, and cannot make a profit — so it does not provide the good.

The heart of the problem is that non-excludability destroys the incentive to reveal a willingness to pay. In an ordinary market you must pay to consume, so demand is expressed through price. For a public good you can consume without paying, so demand is never expressed — the price mechanism has nothing to work with.

A* link. Say precisely why free-riding follows from non-excludability (not just that 'people are selfish'). The chain is: non-excludable → cannot charge non-payers → rational consumers withhold payment (free-ride) → firm earns no revenue → no profit → good not supplied. Naming each link is what earns the AO3 analysis marks.

A free rider consumes a good WITHOUT paying — possible because it is non-excludable.
Each consumer waits for others to pay, expecting to benefit anyway.
Since everyone reasons this way, NO ONE pays.
The firm collects no revenue → cannot profit → does not provide the good.
Non-excludability destroys consumers' incentive to reveal willingness to pay.

See the full worked example for non-provision of public goods - market failure →

The missing market: complete market failure

The free-rider problem means the private sector under-provides or does not provide public goods at all — a missing market and complete market failure.

Because the free-rider problem means no firm can earn revenue, the private sector under-provides the good, or does not provide it at all. Economists call this a missing market: a market that should exist (people clearly value the good) but which the price mechanism fails to create.

This is described as complete market failure — as opposed to partial market failure, where a market exists but produces the wrong quantity (as with a demerit good that is over-produced). For a pure public good, the free-market quantity is zero (or close to it), even though the socially desirable quantity is clearly positive. The market does not merely misallocate resources; it produces nothing at all.

The solution — government provision. Since the market will not supply public goods, the government provides them directly and funds them through taxation (or contracts private firms to build them but pays for them out of tax revenue). Taxation solves the free-rider problem by compelling everyone to contribute, so the good gets funded even though no one would pay voluntarily. This is the standard economic justification for the state providing national defence, street lighting, flood defences and policing.

Note the government still faces a hard question: how much to provide. Because willingness to pay is never revealed through prices, the state must estimate the value of the good — which is why some economists warn of possible government failure (providing too much, too little, or the wrong mix). But that a public good needs some form of collective provision is not in doubt.

Free-rider problem → private sector under-provides or does not provide at all.
This is a MISSING MARKET: a market that should exist but the price mechanism fails to create.
It is COMPLETE market failure (free-market quantity ≈ zero), not partial.
Solution: government provides the good and funds it through TAXATION.
Taxation beats free-riding by compelling everyone to contribute.

See the full worked example for non-provision of public goods - market failure →

Pure vs quasi-public goods

Pure public goods are fully non-rival and non-excludable; quasi-public goods (roads, beaches) have the characteristics only partially, so they can sometimes be charged for.

Very few goods are perfectly non-rival and non-excludable. Economists therefore split public goods into two types.

Pure public goods are fully non-rival and fully non-excludable. National defence is the textbook example: protecting one more citizen costs nothing extra (non-rival) and no citizen can be excluded from the protection (non-excludable). Street lighting and flood defences are close to pure too.

Quasi-public goods (or semi-public goods) have the two characteristics only partially — they are somewhat rival or somewhat excludable, so they sit between private and public goods:

A road is usually non-rival (one more car makes little difference) — but at rush hour it becomes rival (congestion means your journey slows everyone else's). It is usually non-excludable — but a toll booth makes it excludable, so drivers can be charged.
A beach is usually non-rival and open to all — but a crowded beach is rival (less space for you), and a privately owned beach with a gate and an entry fee is excludable.

Because quasi-public goods can be partly charged for (tolls, entry fees), the private sector sometimes supplies them — but often imperfectly, which is why governments frequently provide or subsidise roads, parks and beaches as well.

Feature	Pure public good	Quasi-public good
Non-rivalry	Full (never used up)	Partial (rival when congested)
Non-excludability	Full (cannot charge)	Partial (can charge via tolls/fees)
Examples	National defence, street lighting	Roads, beaches, bridges, parks
Market provision	None (missing market)	Sometimes possible (imperfectly)

A* link. The mark of a strong answer is showing that a characteristic can switch on or off with circumstances: a road is non-rival until it congests; a beach is non-excludable until someone builds a fence. Recognising that quasi-public goods are context-dependent — and that this is why they can sometimes be provided privately — is exactly the nuance examiners reward.

Pure public good = FULLY non-rival AND non-excludable (e.g. national defence).
Quasi-public good = the characteristics hold only PARTIALLY (e.g. roads, beaches).
A road is non-rival until it congests; non-excludable until a toll booth is added.
Because they can be partly charged for, quasi-public goods are SOMETIMES supplied privately.
Characteristics are context-dependent — they switch on/off with circumstances.

See the full worked example for non-provision of public goods - market failure →

Quick recap

A public good has TWO characteristics: non-rivalry and non-excludability — not 'provided by the public sector'.
Non-rivalry = use does not reduce the amount left for others; non-excludability = you cannot exclude non-payers.
A private good is the opposite: rival AND excludable, so the market supplies it normally.
The free-rider problem: non-excludability means everyone waits for others to pay, so no one pays.
No revenue → no profit → the private sector under-provides or does not provide: a missing market (complete market failure).
Government therefore provides public goods, funded by taxation; quasi-public goods (roads, beaches) are only partly public.

Memorise this

Verbatim phrases and definitions Edexcel mark schemes credit.

A public good is a good that is non-rival (one person's consumption does not reduce the amount available to others) and non-excludable (non-payers cannot be prevented from consuming it).
A private good is both rival and excludable.
The free-rider problem: because non-payers cannot be excluded, consumers have no incentive to pay, so the private sector earns no revenue and under-provides or does not provide the good.
A missing market is complete market failure — the free-market quantity of a pure public good is zero, so the government must provide it and fund it through taxation.
Quasi-public goods (e.g. roads, beaches) have the two characteristics only partially, so they can sometimes be charged for and supplied privately.

How it’s examined

High frequency and mostly non-diagram (definition + chain-of-reasoning). Tested in Section A (an MCQ classifying a good, or identifying the characteristics of a public good), Section B short answers (e.g. 'Explain the free-rider problem' or 'explain why the private sector will not provide a public good', 4 marks), and Section C data response, where the (c) 6-mark [KAA] and (d) 8-mark [KAA] / (e) 14-mark [KAA 8 + Eval 6] parts ask you to analyse why a public good is under-provided or to examine whether the state should provide a particular good. Section D (20 marks) essays use it for policy evaluation — e.g. whether all public goods should be provided by the state, where the quasi-public distinction and the risk of government failure are the key evaluation hooks. Examiner reports repeatedly flag defining a public good as 'one the government provides', confusing non-rivalry with non-excludability, and calling merit goods public goods.

Sources: Pearson Edexcel International Advanced Level Economics (XEC11/YEC11) Specification, Issue 2; Edexcel IAL Economics WEC11 Examiner Reports; Edexcel IAL Economics WEC11 mark schemes. Last reviewed 2026-07-01.

Take this whole topic with you

Step-by-step worked examples — Non-provision of public goods - Market Failure

Step-by-step solutions to past-paper-style questions on non-provision of public goods - market failure, written exactly the way a tutor would explain them at the board.

Question type:

1Identify the two characteristics of a public good
Getting startedIdentify & classify• public good, non-rivalry, non-excludability, AO1
Question
State the two characteristics that define a public good, and explain each using street lighting as an example.
Step-by-step solution
1. Step 1
  Non-rivalry. One person's consumption does not reduce the amount available to others. When you walk under a street light, there is exactly as much light for the next person — it is not 'used up'.
2. Step 2
  Non-excludability. Once the light is on, you cannot prevent non-payers from benefiting — everyone on the street sees the light whether or not they contributed.
Answer
Non-rivalry (one person's use does not reduce the amount left for others) and non-excludability (non-payers cannot be excluded) — street lighting has both.
Examiner tip
The marked distinction is naming BOTH characteristics correctly and defining each. Non-rivalry is about quantity (not used up); non-excludability is about payment (can't keep non-payers out). Defining 'public good = government-provided' scores zero.
2Classify goods as private, public or common
Getting startedIdentify & classify• private good, public good, common resource, AO1
Question
Classify each good using the rival/excludable framework: (i) a chocolate bar; (ii) national defence; (iii) fish in the open ocean.
Step-by-step solution
1. Step 1
  (i) A chocolate bar is rival (if you eat it, no one else can) and excludable (the shop won't give it to you unless you pay) → a private good.
2. Step 2
  (ii) National defence is non-rival (protecting one more citizen costs nothing extra) and non-excludable (no citizen can be left unprotected) → a pure public good.
3. Step 3
  (iii) Ocean fish are rival (a fish you catch is one no one else can catch) but non-excludable (no one owns the open sea) → a common resource.
Answer
(i) private good (rival + excludable); (ii) pure public good (non-rival + non-excludable); (iii) common resource (rival + non-excludable).
Examiner tip
Test each good against BOTH axes and name the correct box. Recognising the common resource (rival but non-excludable) shows the two characteristics are independent — a good need not fail on both.
3Explain the free-rider problem
Building confidenceWord problem• WEC11 Section B style• free-rider problem, non-excludability, AO3
Question
Explain the free-rider problem and why it prevents a firm from providing street lighting profitably. (4 marks)
Step-by-step solution
1. Step 1
  Define. A free rider is someone who consumes a good without paying, because its non-excludability means they cannot be stopped.
2. Step 2
  The incentive. Since anyone can enjoy the street light once it is on, each resident reasons: 'I'll benefit even if I don't pay, so I won't pay' — and expects to free-ride on others.
3. Step 3
  Everyone does the same. Because every resident reasons this way, no one pays.
4. Step 4
  The result. With no one paying, the firm earns no revenue, cannot cover its costs, and so cannot provide the lighting profitably.
Answer
Non-excludability lets consumers free-ride (consume without paying); each waits for others to pay, so no one pays; the firm earns no revenue and cannot profit.
Examiner tip
AO3 chain: non-excludable → free-riding → no one reveals willingness to pay → no revenue → no profit. The development mark comes from linking free-riding back to non-excludability, not just asserting 'people are selfish'.
4Explain the missing market and government solution
Building confidenceWord problem• WEC11 Section C style• missing market, market failure, government provision, AO3
Question
Explain why the free-rider problem leads to a missing market, and how government provision solves it. (6 marks)
Step-by-step solution
1. Step 1
  No revenue → no supply. Because free-riding means no firm can earn revenue, the private sector under-provides the good or does not provide it at all.
2. Step 2
  Missing market. A market that should exist (people clearly value the good) is not created by the price mechanism — the free-market quantity of a pure public good is essentially zero.
3. Step 3
  Complete market failure. This is worse than partial failure (where a market exists but produces the wrong quantity): here the market produces nothing at all.
4. Step 4
  Government solution. The state provides the good directly and funds it through taxation, which compels everyone to contribute and so overcomes the free-rider problem.
Answer
Free-riding → no revenue → private quantity ≈ 0 (a missing market, complete market failure); the government provides the good and funds it through taxation, forcing everyone to contribute.
Examiner tip
AO3: state the chain to a missing market and label it COMPLETE market failure (quantity ≈ 0), then give taxation as the mechanism that defeats free-riding. Distinguishing complete from partial failure lifts the answer toward the top of the level.
5Distinguish pure from quasi-public goods
StretchIdentify & classify• WEC11 Section C style• quasi-public good, pure public good, roads, AO3
Question
Explain why a motorway is a quasi-public good rather than a pure public good, referring to both characteristics. (6 marks)
Step-by-step solution
1. Step 1
  Set the benchmark. A pure public good is FULLY non-rival and FULLY non-excludable. Test the motorway against both.
2. Step 2
  Rivalry is partial. A motorway is usually non-rival — one more car makes little difference — but at rush hour it becomes rival: congestion means each extra car slows everyone else's journey.
3. Step 3
  Excludability is partial. It is usually non-excludable, but a toll booth makes it excludable — drivers can be charged, so non-payers CAN be kept out.
4. Step 4
  Conclude. Because both characteristics hold only partially — and can switch off with congestion or a toll — the motorway is a quasi-public good, which is why it can sometimes be supplied (imperfectly) by the private sector.
Answer
A motorway is non-rival until it congests and non-excludable until a toll is added, so both characteristics hold only partially → it is a quasi-public good, not a pure one.
Examiner tip
AO3: show each characteristic switching on/off with circumstances (congestion, tolls). The key insight examiners reward is that quasi-public goods are context-dependent, which is why they can sometimes be charged for and provided privately.
6Examine whether the state should provide a good
StretchWord problem• WEC11 Section C style• government provision, government failure, evaluation, AO3
Question
Examine whether the fact that lighthouses are non-rival and non-excludable means the government must provide them. (8 marks)
Step-by-step solution
1. Step 1
  The case for. A lighthouse is non-rival (one ship seeing the beam takes nothing from another) and non-excludable (passing ships cannot be charged). So the free-rider problem applies: no ship will pay, no firm earns revenue, and the market is missing — a case for state provision funded by taxation.
2. Step 2
  Develop the chain. Because willingness to pay is never revealed through price, only collective funding (taxes or harbour dues) can ensure the lighthouse is built at all — otherwise shipping safety, which everyone values, goes unsupplied.
3. Step 3
  Counter-argument — 'must' is too strong. Provision does not require direct state operation: the government could fund lighthouses via compulsory harbour dues while a private firm builds and runs them. Historically, some lighthouses were funded by charging ships at port — a partial form of exclusion.
4. Step 4
  Judgement. The characteristics justify collective funding (to beat free-riding), but not necessarily state operation. And the government risks its own failure — mis-judging how many lighthouses to build because it cannot read demand from prices.
Answer
The characteristics justify collective (tax/levy) funding to overcome free-riding, but not necessarily direct state operation — the government could fund privately-run provision, and it risks government failure in judging the right quantity.
Examiner tip
'Examine' at Unit 1 is KAA-only (no evaluation marks), so Level 3 needs two developed strands: the free-rider case FOR collective funding, and the nuance that 'provide' can mean 'fund' rather than 'operate', plus the government-failure risk. A one-sided 'the state must provide it' answer caps at Level 1–2.

Model Answers — Non-provision of public goods - Market Failure

High-scoring sample answers for non-provision of public goods - market failure on the Pearson Edexcel IAL XEC11 / YEC11 paper, with examiner-style notes mapping each response to the mark scheme and assessment objectives.

Question 1
WEC11/01 Section C(a) style — Knowledge (2 marks, point-marked)2 marks
[Easy · 2 marks · Section C(a)] Define the term 'public good'.
Model answer
A public good is a good that is non-rival — one person's consumption does not reduce the amount available to others (1) — and non-excludable, meaning non-payers cannot be prevented from consuming it (1).
Why this scores
2/2: one mark for each characteristic correctly stated (non-rivalry and non-excludability). Defining it as 'a good provided by the government' scores zero — the definition is the two characteristics.
Question 2
WEC11/01 Section B style — Knowledge and application (4 marks, point-marked)4 marks
[Easy · 4 marks · Section B] Explain the free-rider problem in the context of public goods.
Model answer
A free rider is someone who consumes a good without paying for it (1). This is possible because a public good is non-excludable — once it is provided, non-payers cannot be prevented from benefiting (1).

Because each consumer knows they will benefit whether or not they pay, they have an incentive to wait for others to pay and free-ride on them (1). But since everyone reasons the same way, no one pays, so the provider raises no revenue and the good is not supplied (1).
Why this scores
4/4: free rider = consumes without paying (1); this follows from non-excludability (1); each consumer waits for others (1); so no one pays and no revenue is raised (1). Linking the behaviour to non-excludability (not just 'selfishness') secures full marks.
Question 3
WEC11/01 Section C(c) style — KAA (6 marks), Levels 1–36 marks
[Medium · 6 marks · Section C(c)] Analyse why the private sector is likely to under-provide, or not provide, a public good such as flood defences.
Model answer
A public good such as flood defences is non-rival (one household being protected does not reduce the protection available to a neighbour) and non-excludable (once a sea wall is built, no household in the area can be excluded from its protection).

Because the good is non-excludable, a private firm that built the flood defences could not charge the households that benefit — any household could refuse to pay yet still be protected. This creates the free-rider problem: each household reasons that it will be protected whether or not it pays, so it has no incentive to pay, and waits for others to fund the wall instead.

Since every household reasons this way, no one pays, so the firm collects no revenue. Unable to cover its costs, the firm cannot make a profit and therefore will not build the flood defences at all.

The result is a missing market: even though flood protection is clearly valued, the price mechanism fails to provide it — an example of complete market failure. The free-market quantity is essentially zero, which is why such goods are typically provided by the government and funded through taxation.
Why this scores
6/6 = KAA Level 3 (5–6): defines the two characteristics, uses non-excludability to derive the free-rider problem, and traces a full chain (no charging → free-riding → no revenue → no profit → not provided) to a missing market / complete market failure. A bare assertion that 'firms won't provide it' without the free-rider chain caps at Level 1–2.
Question 4
WEC11/01 Section C(d) style — KAA (8 marks), Levels 1–38 marks
[Medium · 8 marks · Section C(d)] With reference to the extract, examine why the government, rather than the private sector, provides national defence.
Model answer
National defence is a pure public good. It is non-rival — protecting one more citizen from attack costs nothing extra and takes no protection away from anyone else — and non-excludable — it is impossible to defend a country while leaving out the households that refuse to pay. Because it has both characteristics, the market cannot supply it.

Why the private sector fails. Non-excludability creates the free-rider problem: since no citizen can be excluded from being defended, each has an incentive to enjoy the protection without paying, expecting others to fund it. Because every citizen reasons this way, no one pays voluntarily. A private defence firm would therefore collect no revenue, make no profit, and provide no defence — the free-market quantity would be essentially zero, a missing market and complete market failure.

Why the government succeeds. The government can overcome free-riding because it can compel contributions through taxation. Everyone is required to pay, so the good gets funded even though no one would pay voluntarily. The state can then provide defence at a level judged to reflect the value citizens collectively place on it.

On this reasoning, national defence is provided by the government precisely because its non-rivalry and non-excludability make private provision impossible, while the state's power to tax defeats the free-rider problem that defeats the market.
Why this scores
8/8 = KAA Level 3 (7–8): two developed strands — (1) why the market fails (both characteristics → free-rider problem → no revenue → missing market) and (2) why the state succeeds (taxation compels contributions and beats free-riding) — each traced as a logical chain and applied to national defence. 'Examine' at Unit 1 is KAA-only (no evaluation marks), so the depth of the two chains secures Level 3; a one-line assertion caps at Level 1–2.
Question 5
WEC11/01 Section C(e) style — KAA (8 marks) + Evaluation (6 marks)14 marks
[Hard · 14 marks · Section C(e)] Discuss the view that roads should be treated as public goods and provided free of charge by the government.
Model answer
A public good is non-rival and non-excludable, and a genuine public good cannot be provided by the market because of the free-rider problem — non-payers cannot be excluded, so no one pays, no revenue is raised, and the private sector will not supply it. If roads were pure public goods, this would justify free government provision funded by taxation.

The case that roads resemble a public good. For much of the time a road is non-rival: one more car on an empty motorway makes almost no difference to other drivers. It is also often non-excludable: an ordinary urban street cannot practically charge every user, so building it and letting a private firm charge for it would collapse into the free-rider problem. On these grounds there is a case for the government providing roads free at the point of use and funding them through general taxation.

The case against — roads are really quasi-public goods. However, roads only partially satisfy the two characteristics. At rush hour a road becomes rival: congestion means each extra car slows every other driver's journey — the good is used up. And a road can be made excludable — toll booths, congestion charges and electronic tags already charge drivers on many roads. Because roads can be both rival (when congested) and excludable (with tolls), they are best described as quasi-public goods, not pure public goods, and the private sector can provide some of them.

Evaluation and judgement. Whether roads should be free depends on which road and when. For a quiet rural road that is genuinely non-rival and hard to toll, free public provision makes sense. But for a congested urban route, treating it as 'free' encourages over-use (congestion, pollution) — here charging (a toll or congestion charge) can ration scarce road space and correct the market failure more efficiently than free provision. Free provision also carries an opportunity cost (tax money that could fund healthcare or education) and a risk of government failure if the state builds the wrong roads. On balance, roads should not be treated as pure public goods provided free everywhere: the sensible policy is mixed — free provision where roads are genuinely non-rival, but charging where congestion makes them rival — reflecting their true status as quasi-public goods.
Why this scores
KAA (8): defines the two characteristics and the free-rider problem, then applies them to roads — showing roads are only PARTIALLY non-rival/non-excludable (congestion → rival; tolls → excludable) and are therefore quasi-public goods. Evaluation (6): weighs which road and when, over-use of 'free' congested roads, opportunity cost and government-failure risk, closing with a conditional 'mixed policy' judgement rather than a flat verdict — the discriminator for the top level.
Question 6
WEC11/01 Section D style — KAA (12 marks) + Evaluation (8 marks), best-fit levels20 marks
[Hard · 20 marks · Section D] Evaluate the view that all public goods should be provided by the state.
Model answer
A public good is non-rival (one person's consumption does not reduce the amount available to others) and non-excludable (non-payers cannot be prevented from consuming it). These characteristics generate the free-rider problem: because no one can be excluded, each consumer waits for others to pay, so no one pays, the private sector earns no revenue and provides none of the good. This is a missing market — complete market failure. The question is whether the state provision that follows should apply to all public goods.

The case for state provision. For a pure public good such as national defence or street lighting, the free-market quantity is essentially zero, so leaving provision to the market would mean society goes without goods it clearly values. The government can overcome the free-rider problem because it can compel contributions through taxation, ensuring the good is funded even though no one would pay voluntarily. State provision also allows the good to be supplied at a level that reflects its collective social value and secures important benefits (security, safety, reduced flood risk) that the market cannot deliver.

The case against 'all' and 'state'. Two words in the claim are too strong. First, not all 'public' goods are pure — many are quasi-public goods (roads, beaches, bridges) whose characteristics hold only partially. Because they can be partly charged for (tolls, entry fees) and become rival when congested, the private sector can supply some of them, and charging can even improve efficiency by rationing over-used capacity. Second, 'provided by the state' need not mean produced by the state: the government can fund a public good through taxation while a private firm builds and operates it (e.g. defence equipment, privately-run toll roads) — separating financing from production. State provision also risks government failure: because willingness to pay is never revealed through prices, the government may provide too much, too little, or the wrong mix, and provision funded by taxes carries an opportunity cost.

Evaluation and judgement. Whether all public goods should be state-provided depends on how pure the good is and on what 'provide' means. For a genuinely pure public good (national defence), collective funding through taxation is unavoidable, so the state must at least fund it — the market simply will not. But for quasi-public goods, private provision or charging is often feasible and sometimes more efficient, so blanket state provision is not justified. Even for pure public goods, the state's role is best seen as funding rather than necessarily producing the good, and it must guard against government failure. On balance, the claim is too sweeping: the state should ensure public goods are funded (because the market cannot), but it need not produce all of them, and quasi-public goods can often be left partly to the market. The defensible position is that the state's essential role is to overcome the free-rider problem through funding, with the mode of provision judged good-by-good.
Why this scores
Top level on both strands. KAA (12): accurate definition (both characteristics), the free-rider chain to a missing market / complete market failure, and the taxation solution — developed as multi-stage chains and applied to pure public goods. Evaluation (8): distinguishes pure from quasi-public goods, separates funding from production, and weighs government failure and opportunity cost, reaching a conditional 'fund, don't necessarily produce; judge good-by-good' verdict rather than a flat answer. The pure-vs-quasi distinction and the funding-vs-production point are the discriminators that push Evaluation to the top level.

Key Definitions and Keywords — Non-provision of public goods - Market Failure

Definitions to memorise and the exact keywords mark schemes credit for non-provision of public goods - market failure answers — sharpened from recent examiner reports for the 2026 Pearson Edexcel IAL XEC11 / YEC11 sitting.

Public good
Examiner keyword
A good that is non-rival (one person's consumption does not reduce the amount available to others) and non-excludable (non-payers cannot be prevented from consuming it). It is defined by these two characteristics, not by who provides it.
Private good
Examiner keyword
A good that is both rival (consumption by one person reduces the amount available to others) and excludable (non-payers can be prevented from consuming it) — so the price mechanism works and the market supplies it normally.
Non-rivalry
Examiner keyword
A characteristic of a public good whereby one person's consumption does not reduce the amount available for others — the good is not 'used up' (e.g. one more person seeing a street light).
Non-excludability
Examiner keyword
A characteristic of a public good whereby it is impossible (or prohibitively expensive) to prevent people who have not paid from consuming it (e.g. national defence cannot be switched off for one household).
Free-rider problem
Examiner keyword
Because non-payers cannot be excluded, consumers have an incentive to consume a public good without paying, expecting others to pay. Since everyone reasons this way, no one pays, so the private sector earns no revenue and under-provides or does not provide the good.
Free rider
Examiner keyword
Someone who consumes a good without paying for it, which is possible because the good is non-excludable.
Missing market
Examiner keyword
A market that fails to exist even though people value the good, because the price mechanism cannot function — the case of a pure public good, where the free-market quantity is essentially zero. An example of complete market failure.
Quasi-public good
Examiner keyword
A good that has the two characteristics of a public good only partially — it is somewhat rival or somewhat excludable (e.g. a road that congests, or a beach with an entry fee), so it can sometimes be charged for and provided privately.
Pure public good
A good that is fully non-rival and fully non-excludable (e.g. national defence, street lighting), so the free market provides none of it at all.
Complete market failure
A situation where the market fails to provide a good at all (the free-market quantity is zero), as with a pure public good — contrasted with partial market failure, where a market exists but produces the wrong quantity.

Common Mistakes and Misconceptions — Non-provision of public goods - Market Failure

The traps other students keep falling into on non-provision of public goods - market failure questions — taken from recent Pearson Edexcel IAL XEC11 / YEC11 examiner reports and mark schemes — and how to avoid them.

✕Defining a public good as 'a good provided by the public sector / government'
WEC11 Examiner Reports — recurring error
Why it happens
The name 'public good' sounds like it means 'provided by the public sector', and the government does happen to provide many of them.
How to avoid it
Define it by the TWO characteristics — non-rivalry AND non-excludability. The government provides public goods BECAUSE of those characteristics; the characteristics come first. This is the single most penalised error in the topic.
✕Confusing non-rivalry with non-excludability
WEC11 Examiner Reports
Why it happens
The two terms sound similar and both describe 'public' features, so students blur them or use one to define the other.
How to avoid it
Non-rivalry is about QUANTITY (consumption does not use the good up). Non-excludability is about PAYMENT (you cannot keep non-payers out). Keep them as two separate, clearly defined tests.
✕Calling a merit good (e.g. education, healthcare) a public good
WEC11 mark schemes
Why it happens
Both are often government-provided, so students lump them together.
How to avoid it
A merit good (education, healthcare) is RIVAL and EXCLUDABLE — a private good that is under-consumed because of positive externalities/information gaps. A public good is non-rival and non-excludable. Government provision is not what makes a good 'public'.
✕Treating every 'public' good as a pure public good
WEC11 Examiner Reports
Why it happens
Students learn the two extremes (private vs pure public) and forget the middle case.
How to avoid it
Remember quasi-public goods (roads, beaches, bridges): the characteristics hold only PARTIALLY — a road congests (becomes rival) and a toll makes it excludable. Naming quasi-public goods is a strong evaluation point.
✕Describing the public-good problem as 'the market produces too little'
Why it happens
Students carry over the phrasing used for demerit goods or externalities (partial failure).
How to avoid it
For a PURE public good the market produces essentially NOTHING — a MISSING market and COMPLETE market failure. Reserve 'too little / too much' for partial failure cases where a market does exist.
✕Explaining the free-rider problem as simply 'people are selfish and won't pay'
WEC11 Examiner Reports
Why it happens
Students grasp the outcome (no one pays) but skip the reasoning that produces it.
How to avoid it
Link non-payment to NON-EXCLUDABILITY: because non-payers cannot be excluded, each consumer rationally waits to free-ride on others; since all do so, no one pays and no revenue is raised. The AO3 mark is in the chain, not the word 'selfish'.