Public Goods and Information Failures
~40 min · WEC11 · 1.3.5
WEC11 · 1.3.5 · 40 min
A can't be switched off for someone who hasn't paid, and that single fact about excludability — not any claim about people being cheap — is what forces the into existence and keeps a private market from ever supplying one.
Key terms in this lesson
Before you read on
Two or three questions on exactly what this lesson teaches. Being wrong here is fine — it's the fastest way to find out what to pay attention to next.
Four failures, two axes and one timing question
Two properties, asked as two separate yes/no questions, generate the first half of this lesson. Rivalry: does one person's consumption reduce what's left for anyone else? Excludability: can a non-payer actually be prevented from consuming it? A is rival and excludable — eating a sandwich removes it from the world, and a shop can refuse to hand one over without payment. A is the opposite on both counts: non-rival (one more person consuming it leaves exactly as much available to everyone else) and non-excludable (there's no practical way to stop a non-payer consuming it too). The two properties are genuinely independent, not two names for the same idea — a fish stock in international waters is rival (one trawler's catch is gone for everyone else) but non-excludable (no one can be stopped from fishing it), which is a , a different failure mode again even though it also involves non-excludability.
National defence and a lighthouse are the spec's own classic public goods, and both properties are derivable, not just assertable. Non-rival: one more citizen covered by the same coastal radar network, or one more ship warned by the same lighthouse beam, doesn't require building a second network or a second lighthouse — the existing one already covers them at zero extra cost. Non-excludable: a defence system protecting a harbour, or a beam warning every ship in range, cannot be selectively switched off for the one household or the one ship that didn't pay, without also switching it off for everyone next to them. A toll motorway, by contrast, is excludable (a barrier can refuse non-payers) even at a quiet hour when it's also non-rival — a real fourth combination worth knowing, but not one this spec names directly; the two categories the spec actually tests are private and public goods, plus the boundary case of a common resource. A national park spanning thousands of square kilometres is non-excludable for a third, genuinely distinct reason from either of the two above: not because a broadcast signal can't be aimed only at payers, but because there's no economically practical way to fence or gate a perimeter that size — a real spec-tested angle in its own right, not just a restatement of 'nobody built a fence.'
Because a public good is non-excludable, no market can charge a price for it the way an ordinary private-good market does — there's no way to withhold supply from a non-payer, so there's no way to enforce payment at all. This is the seed of the : since consumption doesn't depend on payment, a rational individual's own decision to pay or not pay has no effect on whether they personally receive the good. The mechanism block below derives exactly why that fact alone is enough to collapse voluntary private provision to zero — not as an assumption about selfishness, but as the outcome every potential contributor is separately pushed toward at once.
Symmetric information exists where both sides of a transaction know the same relevant facts. is where one side knows something material the other doesn't, and the spec names four contexts where this repeatedly matters: healthcare (a patient can't easily verify whether a recommended test or treatment is actually necessary), education (a prospective student can't fully verify a course or institution's real quality before enrolling and paying), pensions (a saver usually can't judge whether a pension product's fees and projected returns are competitive), and insurance (an insurer usually can't fully verify an individual applicant's true risk). The significance isn't only that one side knows less — it's that the informed side's own incentives shift once the gap exists: a seller who knows more than a buyer has less reason to volunteer an unfavourable fact, and a buyer who suspects this discounts what they're willing to pay, which is exactly the mechanism behind adverse selection shrinking a market below what full information would produce.
is often confused with asymmetric information in general, but it names a specific, different mechanism: a change in behaviour that happens *after* a contract is signed, because the contract itself has shifted the cost of a risk onto someone else. This is genuinely distinct from , which is about a hidden characteristic that already existed and was already asymmetric *before* the contract — a driver's true accident-proneness, known to them and not to the insurer, at the moment they apply. Moral hazard needs no hidden information at the point of signing at all; it only needs that, once the contract exists, one side's actions affect a cost the other side is now paying. A third insurance-market information problem is distinct from both of these: at the point a loss is already claimed, a claimant may leave out details of how it happened — for example, that a car or house was left unlocked or without its alarm set — that would have reduced or voided the payout had the insurer known them. Unlike adverse selection, nothing about this was hidden before the policy was signed; and unlike moral hazard, the claimant's behaviour didn't change what happened, only what they disclosed about it afterwards. Left uncaught, this inflates the insurer's payouts; caught, it gets the claim rejected — both outcomes the same imperfect-information mark scheme credits. The worked chain below derives the first of these three mechanisms precisely for health insurance, using the exact wording a real examiner report confirms was needed for full marks.
Speculation means buying an asset mainly because you expect its price to rise, rather than for the income or use it directly provides — a normal and often useful market activity that helps prices adjust quickly to new information. A is what happens when speculation becomes self-reinforcing, and that self-reinforcement has a specific starting point and a specific breaking point worth naming precisely, because the diagram below is built around exactly these two moments. First, a genuine change — new technology, falling interest rates, a policy shift — gives the asset's price a real reason to rise: this is the displacement, and while the price is still moving in step with that genuine change, it isn't yet a bubble at all. The bubble only begins at the divergence point: the moment further buying stops being explained by any change in the asset's real earning power and starts being explained only by the expectation that the price itself will keep rising. Past that point, the mechanism is purely self-reinforcing — a price rise attracts buyers who are buying mainly because the price has been rising, which pushes the price up further, which attracts more buyers on the same reasoning, now fully detached from the asset's underlying earning power or usefulness. In housing this shows up as prices rising faster than incomes or rents can justify (Munich's housing prices roughly doubling over a single decade is a real, examined context); in stocks and shares it shows up as valuations detaching from a company's actual profits or growth prospects. The test is the same in both: is the price rise explained by a genuine change in the asset's future income, or only by the expectation that the price itself will keep rising?
Mechanism
Under-provision is a payoff problem, not a generosity problem
The mechanism is a payoff comparison, not a claim about generosity. Take any single potential contributor facing a good that, once provided, cannot be withheld from a non-payer. Their decision has exactly two possible states of the world to weigh: either enough OTHER people fund the good without them, in which case they receive the full benefit whether or not they personally contribute — so paying only makes them worse off, by exactly the size of their own contribution, for the identical benefit; or NOT enough other people fund it, in which case their own contribution — almost always a small fraction of the total cost — isn't enough to unlock the benefit anyway, so paying buys them nothing either. In both states of the world, withholding payment is at least as good as paying, and in the first state it's strictly better. This holds for every potential contributor simultaneously, which is exactly why the outcome isn't "some people are cheapskates" — it's that non-contribution is the dominant strategy even for a genuinely public-spirited person facing this exact payoff structure, which is precisely what spec point 1.3.5.3(b) is testing when it asks WHY the free-rider problem stops private provision, not merely whether a student can state that it does.
Worked, in full
Four fishing crews and one lighthouse: the free-rider outcome, in real numbers
- 01
Suppose four fishing crews operate near a hazardous stretch of coast. Each crew independently values the safety benefit of a lighthouse — fewer wrecks, lower insurance premiums — at £90 per year. A lighthouse costs £300 per year to build and run, and once built, its beam warns every ship in range; there's no way to switch it off for a boat that hasn't paid.
Earns: K — the scenario set up with explicit, checkable numbers and the non-excludability assumption stated directly, not left implicit.
- 02
Total social benefit is 4 × £90 = £360 a year, against a cost of £300 — building the lighthouse is worthwhile in aggregate, with £60 of net social benefit available if it's built. If the four crews split the cost evenly, each pays £300 ÷ 4 = £75, leaving each with a net benefit of £90 − £75 = £15 if everyone actually pays their share.
Earns: An1 — the socially efficient outcome and the individually-rational cooperative outcome both computed explicitly, establishing that cooperation would genuinely make every crew better off if it held.
- 03
Now consider a single crew's incentive, taking the other three crews' behaviour as given. If the other three crews' payments already cover the £300 cost regardless of this crew's decision, this crew receives the full £90 benefit whether or not they pay — so not paying nets £90, paying nets only £15. If the other three crews are NOT paying enough, this crew's own £90 valuation is still far short of unilaterally covering the £300 cost alone, so paying buys them nothing extra either. In both states of the world, not paying is at least as good as paying, and in the first it's better by £75 (£90 versus £15).
Earns: An2 — the individual payoff comparison run for both possible states of the world, showing non-contribution weakly dominates rather than simply asserting it.
- 04
Because this reasoning is identical for every one of the four crews at once — nothing about it depends on which specific crew is doing the reasoning — the unique outcome under purely voluntary, uncoordinated decisions is zero contributions and no lighthouse, even though every crew genuinely wants it built and the total benefit exceeds the cost by £60 a year. This is the free-rider problem as a dominant-strategy equilibrium: it survives even if every actor is fully public-spirited, because the payoff structure itself, not anyone's selfishness, is what produces the failure.
Earns: Eval — the result generalised from one crew's reasoning to the whole group, and the conclusion connected explicitly to what the free-rider problem does and doesn't require.
Worked, in full
Moral hazard, traced through what a contract changes after it's signed
- 01
Before taking out health insurance, an individual bears the full expected cost of their own risk-related choices — if they take up a risky activity or skip a precaution, they personally pay for the consequences in full, so their private incentive to take care is aligned with the actual cost their choices create.
Earns: K — the pre-contract baseline stated explicitly as the comparison point, not skipped.
- 02
A health insurance contract transfers the financial consequence of a bad outcome from the individual to the insurer, in exchange for a premium fixed once the policy is signed. Crucially, that premium doesn't change based on what the individual actually does afterwards — only the probability of a claim does.
Earns: An1 — the mechanical effect of the contract (what moves, what doesn't) stated precisely rather than left as a vague 'insurance changes incentives'.
- 03
Because part of the cost of a risky choice now falls on the insurer rather than the individual, the individual's rational, self-interested calculation changes: the same risky action that wasn't worth it before the policy existed can become worth it afterwards, purely because someone else is now paying part of the bill. This is exactly the mechanism a real examiner report credits, in the embedded evidence below.
Earns: An2 — the shift in the individual's own payoff calculation named as the mechanism, with the confirmed examiner-report line as direct evidence this is the actual mark point, not an invented elaboration.
- 04
This is why moral hazard is a genuinely different failure from adverse selection, even though both get filed under 'information problems'. Adverse selection is about a characteristic — the individual's true risk type — that already existed and was already known unevenly BEFORE the contract, and doesn't change because of it. Moral hazard needs no hidden information at all at the point of signing; it only needs that a contract, once in force, changes what one side's own actions cost them. The same insurance market can suffer from both at once, but they earn separate, distinct marks — collapsing them into one answer is the trap named below.
Earns: Eval — the two failures explicitly distinguished on the dimension that actually separates them (timing and cause), rather than an asserted difference with no mechanism behind it.
Source — Examiner report, Jan 2021
"Those that did this successfully explained that as people had the insurance, they knew that if they had an accident and ended up in hospital the health insurance policy would pay so people were willing to take more risks."
x-axis: Time · y-axis: Asset price, £
- Fundamental value
- A slow-moving line reflecting the asset's genuine underlying worth — discounted future earnings for a share, discounted future rents for a house — largely flat or gently rising across the timeframe shown.
- Market price
- Tracks the fundamental-value line closely at first, then departs sharply upward during the euphoria phase, peaks, and falls back — often faster than it rose — during the crash.
- Displacement
- A genuine change (new technology, falling interest rates, a policy shift) gives the price rise a real initial justification — this part of the rise still tracks the fundamental-value line.
- Divergence point
- Where the market-price line visibly separates from the fundamental-value line — past this point, further buying is driven by the expectation of future price rises, not by any change in the asset's real value.
- Peak
- The highest point the market price reaches, immediately before profit-taking by earlier, better-informed buyers begins.
- Crash / correction
- The market price falls back toward the fundamental-value line — often overshooting below it — as the same herd behaviour that drove the price up now drives it down.
Common error: Drawing the market-price line rising indefinitely with no divergence point marked, or crashing all the way to zero rather than back toward the fundamental-value line.
Correct: The market price is shown departing from a clearly separate fundamental-value line at an identifiable point, and the crash returns it toward — not necessarily all the way to, and not below zero — that same fundamental-value line. The diagram's whole point is showing the GAP between price and value, not just 'price went up then down'.
In your own words
In one sentence: why can a market for a public good not simply set a market-clearing price the way an ordinary private-good market does, even though the good clearly has genuine positive value to the people who'd consume it?
Complete it yourself
Complete the chain — deposit protection and risk-taking in banking
- 01
Many governments guarantee bank deposits up to a certain limit, and in practice have repeatedly stepped in to prevent very large banks from failing outright, to protect depositors and the wider financial system.
- 02
Once this guarantee exists, part of the financial consequence of a bank's own risky lending decisions is shifted away from the bank and its depositors and onto the government — ultimately, the taxpayer — if things go badly wrong.
- 03
Because the bank no longer bears the full downside of a risky loan portfolio, its rational, profit-seeking response is to take on more risk than it would if it alone bore every loss — the same mechanism as the health-insurance example above, moved from a person's own risk-taking to a firm's. This is moral hazard, not a difference in what the bank knew when the guarantee was granted.
Named traps
- public-goods-vs-public-sector
- Confirmed directly in an examiner report: "A common misconception was the public goods are any good paid for by the government confusing public goods and public sector." [Oct21 ER, Q9] A road, a hospital bed, or a school place funded by government is not automatically non-rival and non-excludable — each of those is genuinely rival (one patient's bed is unavailable to another) even though the state pays the bill. Test the actual properties, never who wrote the cheque.
- moral-hazard-vs-information-gap
- Examiner reports confirm a specific, recurring conflation: candidates treat moral hazard as just another way of saying "there's an information gap", rather than identifying the specific mechanism — that the cost of a riskier action is shifted onto a third party (an insurer, a deposit guarantee, a taxpayer) once a contract or guarantee already exists [Jan23 ER, Q8]. Naming general asymmetric information where a question specifically asks about moral hazard is marked as the wrong concept, not a partial answer.
- stops-at-information-failure-without-the-microeconomic-effect
- Confirmed in an examiner report on a travel-insurance essay: "Many could use the stem to explain why consumers did not buy travel insurance but needed to consider the microeconomic effects of this." [Oct23 ER, Q14 essay] Naming that an information gap exists is only the first stage of the chain — the marks are for what it actually does to the market: under-consumption, a shrinking pool of buyers, or, on the adverse-selection side, rising average premiums as the buyer pool skews toward higher-risk applicants. A fully evaluative answer goes one stage further again: the same anchor question's 8-mark Evaluation band credits weighing that microeconomic effect against remedies that may already be closing the information gap, and against rival, non-informational explanations for the same observed under-consumption, before concluding imperfect information is actually the operative cause. Confirmed remedies, verbatim from the mark scheme: "The internet may help close the information gap that results in the market failure"; "Market failure may be reduced as the insurance company can gain permission to find medical records/ contact doctor"; "Insurance companies may share information on consumers who may say they have not claimed in 5 years. This can be checked by the insurance company" [Oct 2023 WEC11/01 MS, Q14] — and the same logic extends to disclosing concrete cost data directly, such as a published medical-evacuation cost estimate that lets a traveller weigh the real risk themselves rather than relying on the insurer's word for it. Confirmed rival, non-informational explanations, equally verbatim: "Consumers not taking out medical/ health insurance may be because they cannot afford the premium" [Oct 2023 WEC11/01 MS, Q14] — an affordability constraint, not an information gap — and a consumer who already has the relevant information but has rationally judged a small-probability risk not worth the premium, which is a considered decision, not a market failure at all. A third rival explanation sits entirely outside this spec point: "Market failure in insurance markets may be the result of irrational behaviour rather than the result of imperfect information (habitual behaviour, inertia, herding and calculation problems)" [Oct 2023 WEC11/01 MS, Q14] — spec 1.3.2.1's own irrational-consumer-behaviour content, derived in full in rational-decisions-and-demand.ts, which can produce the identical observed under-consumption with no information gap doing any of the actual work. A Level 3 evaluative answer names at least one live remedy or rival explanation and uses it to qualify the conclusion, rather than leaving 'imperfect information causes under-consumption' standing as an unconditional claim.
- claims-stage-nondisclosure-is-a-third-insurance-information-problem
- Confirmed directly in the mark scheme: "Incomplete information may result in claims being rejected"; "When making claims the consumer may leave information out that would result in a lower or no payout- for example, they left the car or house unlocked or without the security alarm set" [Oct 2023 WEC11/01 MS, Q14]. This is a third, separately-creditable insurance information problem — not a restatement of adverse selection or moral hazard. Adverse selection is a risk-type fact hidden BEFORE the policy is signed; moral hazard is a behaviour change that happens AFTER signing, because a cost has shifted onto someone else; claims-stage non-disclosure is a fact withheld only AFTER a loss has already occurred, to avoid a reduced or rejected payout — nothing was hidden at signing, and nothing about the claimant's own behaviour changed because of the contract. Naming only two of the three when a question's stem describes the third is marked as the wrong mechanism, not a partial answer.
- causes-not-effects-of-a-bubble
- Confirmed in an examiner report: "The knowledge of market bubbles was generally sound. Too many focused on the causes of a bubble rather than the effects... Many approached this from the perspective of positive effects of a bubble before it bursts and how people will benefit and then the negative effects when the market bubble bursts." [Jan23 ER, Q12e] A question asking for the IMPACT of a bubble wants what happens to households, firms, lenders and the wider economy as it inflates and as it bursts — not a repeat of how it started. Structuring the pre-burst upside as KAA and the post-burst downside as evaluation is a legitimate technique, but only once both sides are actually about effects, not causes.
- assuming-a-named-public-good-stays-purely-non-rival
- A real, confirmed evaluative angle: New Zealand's national parks are a genuine, spec-relevant public-goods example, but the confirmed exam angle tests whether a candidate notices that heavy visitor numbers can introduce rivalry through overcrowding and car-park congestion [Jan23 ER, Q12d]. "Public good" isn't a permanent property of one specific real good — it's a description of its properties at a given level of use, and those properties can change.
- a-non-excludable-public-good-can-still-contain-an-excludable-activity
- Confirmed in the same examiner report as the entry above, on the identical national-parks context: alongside the rivalry-through-overcrowding angle, "the other responses tended to focus on paying for activities such as a kayaking. This evaluation was well done by candidates." [Jan23 ER, Q12d] Basic entry to the park can stay genuinely non-excludable — no fee, no barrier — while one specific activity inside it (kayak or ski-equipment rental, a guided tour, a permit for one named trail) is excludable in the ordinary sense: a business can simply refuse to hand over the kayak to someone who hasn't paid. This is a different mechanism from the congestion-driven rivalry traced above, and mark-scheme-confirmed as a separate, creditable evaluative point in its own right — not a restatement of it, and not evidence that the whole park has become excludable.
The conditional move
Complete: "Direct government provision is the best response to the under-provision of a public good only if ___."
Complete: "A rapid rise in an asset's price is evidence of a genuine speculative bubble, rather than a justified re-pricing, only if ___."
Beyond the spec
The spec teaches free-riding as a fixed outcome — public goods are always under-provided — without explaining why some real groups do organise voluntary provision (a residents' association funding a shared garden) while others never do (no nation has ever voluntarily crowdfunded its own defence). Knowing the actual mechanism is what lets an answer explain a real exception instead of only reciting the rule.
Paul Samuelson's 1954 paper "The Pure Theory of Public Expenditure" (Review of Economics and Statistics) gave the free-rider problem its first formal mathematical treatment, built on exactly the non-rivalry property this lesson derives from first principles above. Mancur Olson's The Logic of Collective Action (1965) then asked a question the spec doesn't: why do some groups manage to fund a shared good voluntarily, when the free-rider logic above says none should? Olson's answer is that group SIZE changes the mathematics, not just whether excludability exists. In a small group, one member's free-riding is individually noticeable and their own share of the total benefit is a large fraction of it, so voluntary cooperation can survive; in a large group, any single free-rider is invisible and their share of the total benefit is tiny, so the same reasoning that lets ten households jointly fund a shared driveway repair collapses completely once the group is a population of millions. The free-rider problem isn't a fixed switch — it gets mechanically worse as the group gets bigger, which is also most of why Elinor Ostrom's later, Nobel-winning work (2009) on community-managed common resources focused specifically on small, tightly-bounded groups: Olson's mechanism is exactly what her documented exceptions had to overcome.
Beyond the spec
The spec asks you to state that information gaps matter in healthcare, education, pensions and insurance, but doesn't explain how a market can partially fight back against them — which is the difference between an answer that describes a market failure and one that can evaluate whether it's likely to persist.
Kenneth Arrow's 1963 paper "Uncertainty and the Welfare Economics of Medical Care" (American Economic Review) is the founding paper of health economics, built on exactly the healthcare context the spec names: because a patient usually can't verify whether a recommended treatment is actually necessary, the doctor-patient relationship is a textbook case of asymmetric information with the informed party also acting as the seller. George Akerlof's 1970 paper "The Market for Lemons" (Quarterly Journal of Economics) showed a more severe version of the same problem: in a used-car market where sellers know a car's quality and buyers don't, buyers rationally offer only an average price, which drives genuinely good cars out of the market entirely — their owners won't sell at the average price — leaving only 'lemons', and in the extreme case, no market at all. Akerlof shared the 2001 Nobel Memorial Prize with Michael Spence and Joseph Stiglitz specifically for showing the other half of the story: markets don't just collapse passively, they develop tools to fight back. Spence's signalling (1973) explains why the informed party sometimes pays to prove their type — a job applicant investing in a degree partly to signal ability, or an insurer requiring a medical exam before a large life-insurance policy. Stiglitz's screening explains why the UNinformed party can design a menu of contracts that gets the informed party to reveal their type voluntarily — a low premium with a high deductible alongside a high premium with a low deductible, which a genuinely careful driver self-selects into differently than a risky one would. Neither tool eliminates the information gap the spec asks you to identify — but naming the market's own response is what separates an answer that stops at 'there is a market failure' from one that can evaluate how much of it survives in practice.
Beyond the spec
The spec asks you to describe how a bubble arises but gives no named structure for the stages — without one, an answer tends to collapse into a single vague sentence ('prices went up too much') instead of a genuine multi-stage account.
Hyman Minsky's Financial Instability Hypothesis (developed through the 1970s-80s) and Charles Kindleberger's Manias, Panics, and Crashes (1978, later editions with Robert Aliber) give the classic named stage structure behind 'how bubbles arise': displacement (a genuine change — a new technology, a policy shift, a fall in interest rates — creates a real initial reason for optimism), boom (prices rise, more buyers enter, credit expands to fund purchases), euphoria (buyers extrapolate the recent price rise forward and buy expecting further rises rather than judging the asset's underlying value — the exact point a justified price rise becomes a speculative bubble), profit-taking (early, better-informed buyers start quietly selling), and panic (the reversal becomes visible, and the same herd behaviour that drove the price up now drives it down, often faster than it rose). The term 'Minsky moment' — the point the panic stage begins, usually triggered when highly leveraged buyers can no longer service their debt and are forced to sell — entered mainstream financial-press usage after the 2008 financial crisis specifically because Minsky's model, largely ignored by policymakers for the two prior decades, described that crisis's mechanics unusually precisely.
Retrieval — with feedback on every choice
A city's New Year fireworks display is set off from a barge in open water, visible to anyone within several kilometres with no ticket, fence, or paywall of any kind, and one more household watching does not reduce what any other household sees. Which combination of properties does the display have?
In a health insurance market, applicants know their own health history far better than the insurer does, and the insurer cannot cheaply verify it. If the insurer sets one average premium for everyone, which group is most likely to buy the policy, and what does this do to the insurer's costs over time?
An asset's price has risen sharply for several months. Survey evidence shows most recent buyers expect the price to keep rising, and few can point to any change in the asset's underlying earnings or rental income to justify the price reached so far. Which term most precisely describes this situation?
New Zealand's national parks charge no entry fee and have never restricted visitor numbers. Over the past decade, annual visitor numbers have more than doubled, and rangers now report queues at the main car parks and overcrowding on the most popular trails during peak season, while quieter trails in the same parks remain uncongested.
Using the concepts of rivalry and excludability, explain why the parks are best described as moving away from being a pure public good, rather than as having become a private good.
Same question, every level
Discuss the extent to which the free-rider problem justifies direct government provision of a good, rather than leaving its provision to the private market. (VERIDIAN-original question, written in the style of the 'Discuss'-type essay format confirmed across multiple WEC11 series — not a reproduction of any single past-paper question.)
14 marks available
Some goods, like street lighting or national defence, are hard to charge people for because everyone can use them anyway. This means people might not pay for them, so the government usually provides them instead of the market.
Descriptive only — no rivalry/excludability terminology, no chain connecting non-excludability to an individual's incentive, evaluation is a bare assertion with no support.
Same question, every level
Evaluate the extent to which imperfect information, rather than any other factor, explains the under-consumption of insurance by consumers who would benefit from cover. (VERIDIAN-original question, written in the pattern of WEC11's Section D essay format — 20 marks total, split 12 for Knowledge/Application/Analysis and 8 for Evaluation, confirmed directly against the Oct 2023 WEC11/01 mark scheme's own KAA/Eval indicative content for exactly this topic — not a reproduction of any real past-paper question.)
20 marks available
Insurance companies don't always know everything about the person buying a policy, like how healthy they really are. This means some riskier people might get insurance too cheaply, which isn't fair on the insurance company. Because of this, imperfect information is a problem for insurance markets.
Descriptive only — no named concept (asymmetric information/adverse selection is never stated), no mechanism for why a hidden risk-type produces any specific market outcome, and the closing sentence restates the claim rather than establishing a microeconomic effect. Floor band on both scales.
- Public good: non-rival AND non-excludable (both). Private good: rival AND excludable. Common resource: rival but non-excludable.
- Free-rider problem: non-excludability makes not-paying pay off at least as well as paying, for everyone at once — provision can collapse even when total benefit > cost.
- Moral hazard = behaviour changes AFTER a contract. Adverse selection = hidden information exists BEFORE it. Different failures, different marks.
- Bubble: price rises mainly because buyers expect further rises, not because underlying value changed.
- Public goods ≠ public sector. A good the government pays for isn't automatically non-rival and non-excludable.
- A public good's non-excludability can be partial: overcrowding makes it more rival, but a specific paid activity inside it (equipment rental, a guided tour) can be excludable even when general entry isn't.
Not affiliated with or endorsed by Pearson Edexcel. Every quotation and figure attributed to a mark scheme or examiner report in this lesson was independently verified against the primary Pearson document, not carried over from prior course material. The one exact quotation used — the Jan 2021 examiner-report line on health-insurance moral hazard, in the second worked chain — replaces a paraphrase the prior VERIDIAN-ECON build presented as verbatim; the wording used here is the text independently read directly from the source page image.
A city's New Year fireworks display is set off from a barge in open water, visible to anyone within several kilometres with no ticket, fence, or paywall of any kind, and one more household watching does not reduce what any other household sees. Which combination of properties does the display have?
- ARival and excludable
This describes a private good — the exact opposite of both properties given in the stem, which explicitly says one more viewer doesn't reduce anyone else's view and there's no paywall at all.
- Non-rival and non-excludable
Correct. One more household watching leaves the display exactly as visible to everyone else (non-rival), and with no ticket, fence, or paywall, no household can be prevented from watching (non-excludable) — a genuine public good, not because it's free, but because both properties independently hold.
- CRival and non-excludable
This is a common resource, not the scenario described — the stem explicitly states one more viewer doesn't reduce what's available to anyone else, which rules out rivalry.
- DNon-rival and excludable
This describes a club good — but the stem specifically says there's no ticket, fence, or paywall, which rules out excludability.
Traps tested: Opposite properties · Misreads non rival clause · Misreads non excludable clause
In a health insurance market, applicants know their own health history far better than the insurer does, and the insurer cannot cheaply verify it. If the insurer sets one average premium for everyone, which group is most likely to buy the policy, and what does this do to the insurer's costs over time?
- AMostly healthy applicants buy it, lowering the insurer's average claims cost
This reverses the actual direction. An average price is a bargain for higher-risk applicants and comparatively poor value for lower-risk ones, so the buyer pool skews toward higher risk, not lower.
- Mostly higher-risk applicants buy it, since the average price is a bargain for them, pushing the insurer's average claims cost up over time
Correct. This is adverse selection: the applicants who know they're higher-risk get the most value from a price averaged across the whole population, so they disproportionately buy in, and the insurer's actual claims experience ends up worse than the price assumed.
- CHealth risk doesn't affect who buys, since insurance is compulsory in most markets
The stem describes a specific market where the insurer is setting a single average premium and doesn't state the policy is compulsory — this answer imports an assumption the scenario never gives.
- DThe insurer's costs stay the same either way, since premiums are set to cover the average risk
The premium was set assuming the average risk of the WHOLE population — but once self-selection shifts who actually buys, the buyer pool's true average risk is no longer the population average the price was based on.
Traps tested: Direction reversed · Ignores given scenario · Ignores selection effect
An asset's price has risen sharply for several months. Survey evidence shows most recent buyers expect the price to keep rising, and few can point to any change in the asset's underlying earnings or rental income to justify the price reached so far. Which term most precisely describes this situation?
- AA fundamentals-driven price rise
This is directly contradicted by the stem, which states few buyers can point to any change in underlying earnings or rents.
- A speculative bubble — the price rise is driven mainly by the expectation of further price rises, not by a change in the asset's underlying value
Correct. Buyers extrapolating a recent price trend forward, with no accompanying change in fundamentals, is the defining test given in the teach block above.
- CA fall in price elasticity of supply
This is an unrelated concept — PES concerns how responsive quantity supplied is to a price change, not what's driving the price change itself.
- DMoral hazard among buyers
Moral hazard requires a contract that shifts the cost of a risk onto someone else. Nothing here describes a contract at all — this is a description of speculative price expectations.
Traps tested: Ignores the stated evidence · Wrong concept entirely
New Zealand's national parks charge no entry fee and have never restricted visitor numbers. Over the past decade, annual visitor numbers have more than doubled, and rangers now report queues at the main car parks and overcrowding on the most popular trails during peak season, while quieter trails in the same parks remain uncongested.
Using the concepts of rivalry and excludability, explain why the parks are best described as moving away from being a pure public good, rather than as having become a private good.
- The parks remain non-excludable throughout (no fee, no restriction on entry), so they haven't become a private good — but at peak times and on popular trails they're no longer non-rival, because one more visitor's use of the car park or a crowded trail now measurably reduces the experience or availability for other visitors, which is exactly the rivalry test, independent of excludability
Correct, and fully integrated: it keeps excludability explicitly unchanged, isolates rivalry as the property that's shifted, ties the shift to the specific evidence given (car park queues, popular-trail crowding, quieter trails unaffected), and correctly treats this as a partial reclassification rather than a full one.
- BThe parks have become excludable, since rangers can now identify and limit who enters
Nothing in the stimulus describes a fee or an entry restriction being introduced — only queuing caused by visitor volume. Rangers observing overcrowding isn't the same as the parks gaining a mechanism to exclude non-payers.
- CThe parks have become fully private goods, since overcrowding shows people are now competing for access
A private good requires BOTH rivalry and excludability. Overcrowding only establishes rivalry — excludability hasn't changed at all, since there's still no fee or barrier restricting entry.
- DThere's no real change, since parks this large could never realistically become congested
This is directly contradicted by the stimulus's own evidence of car park queues and popular-trail overcrowding at peak times.
Traps tested: Invents a fact not in the stimulus · Confuses partial and full reclassification · Ignores the stated evidence
Practice this for real
This site teaches the mechanism; the exam is sat on Pearson's own real questions. Go find and attempt these yourself — nothing here substitutes for actually sitting a timed paper.
- Examiner report
- Jan 2021 · Q9 — cited directly in this lesson
Select International Advanced Level → Economics → any series, then look for WEC11.
Up next
Government Intervention in Markets
A maximum price and a minimum price are the same lever pulled in opposite directions — and pulling it in the wrong place is exactly how a fix for market failure becomes government failure itself.
40 min