Economics 9708/12 — February/March 2023

Background Concept

Goods can be classified along two dimensions: rivalry (whether one person's consumption reduces the amount available for others) and excludability (whether it is possible to prevent someone from consuming the good unless they pay). These dimensions define four types:

• Private goods: rival and excludable (e.g., a sandwich, a pair of shoes).
• Public goods: non-rival and non-excludable (e.g., national defence, street lighting).
• Common resources: rival but non-excludable (e.g., fish in the ocean, clean air).
• Club goods: non-rival but excludable (e.g., satellite television, a private park).

Market provision works best for private goods because the price mechanism can function: firms supply the good to those who pay, and competition drives efficiency. The other three categories lead to some form of market failure (free-rider problem, tragedy of the commons, or under-provision).

Understanding the Question

The question asks which combination of characteristics makes a good “most suitable to be provided by the market.” This requires knowing that markets rely on prices to allocate resources, and prices can only work if the good is excludable (so people who do not pay can be excluded) and rival (so there is a cost to producing an additional unit, and price reflects scarcity). Option B is “excludable and rival” – that is exactly a private good.

Approach

Consider each option in turn and think about whether a market would efficiently provide a good with those properties. Ask: Can the producer make people pay? Will consumption by one person affect the supply for others? If both answers are “yes”, the market can operate well. If either is “no”, the market is likely to fail.

Step-by-Step Reasoning

1. Option B – excludable and rival (private good).
   Excludable means the seller can charge a price. Rival means each unit consumed reduces what is left, so the price reflects the opportunity cost. A market will allocate these goods efficiently: those who value the good most are willing to pay the higher price, and profit-seeking firms supply the quantity where marginal cost equals marginal benefit.

2. Option A – excludable and non-rival (club good).
   Excludable allows the seller to charge, but non-rival means the marginal cost of an extra user is zero (or very low). The efficient price would be zero, but the firm charges a positive price to cover fixed costs, leading to under-consumption (a deadweight loss). Markets can still provide such goods (e.g., streaming services), but they are less efficient than markets provide for private goods. Therefore, this is not “most suitable.”

3. Option C – non-excludable and non-rival (public good).
   Non-excludable means no one can be forced to pay, so free-riding occurs. Non-rival means the good is not used up. The private market would not produce it at all because firms cannot capture revenue. This is the classic case of market failure; government provision is necessary. Clearly not suitable for market provision.

4. Option D – non-excludable and rival (common resource).
   Non-excludable means anyone can use it, but because it is rival, overuse and depletion occur (tragedy of the commons). Markets do not prevent overconsumption because no one owns the resource. Government regulation or communal management is needed, not market provision.

Thus, only option B describes a good that can be allocated efficiently by the market.

Key Takeaways

• Market provision works best for private goods: excludable and rival.
• The other three combinations each involve some market failure (free-rider, tragedy of the commons, or inefficiency from positive pricing of zero-marginal-cost goods).
• Understanding these classifications helps analyse when government intervention may be justified.

Common Mistakes

• Confusing “non-rival” with “non-excludable”: They are separate dimensions. A satellite TV signal is non-rival (your watching does not reduce my ability to watch) but excludable (the provider scrambles the signal unless you pay).
• Assuming all goods are best provided by markets: Many goods require collective action; the question specifically asks for “most suitable”, and private goods are the standard case.
• Forgetting that excludability is necessary for a price to be charged: Without excludability, the market cannot operate because people can free-ride.

Things to Be Careful About

• Read each option carefully: the order of the two characteristics matters.
• Note that “most suitable” implies a comparison. Even though club goods can be provided by markets, private goods are more straightforward because the efficient allocation aligns with market allocation (marginal cost equals price, which equals marginal benefit).
• In exam contexts, you may be asked to identify which type of good a given example is. Practice classifying goods using the two-by-two matrix.