Economics 9708/32 — February/March 2017

Background Concept

Allocative efficiency is a state of the economy in which production represents consumer preferences. It occurs when it is impossible to reallocate resources to make one consumer better off without making another worse off. The condition for allocative efficiency in a market is that the price consumers are willing to pay (which reflects the marginal benefit to society) equals the marginal cost of producing the good. In symbols: P = MC. When this holds, the right quantity of the good is being produced from society's point of view.

Market failure occurs when free markets fail to achieve allocative efficiency. Common causes include externalities (where the price does not reflect all social costs or benefits), public goods, imperfect information, and monopoly power. Government intervention, such as taxes, subsidies, or regulation, can sometimes correct these failures and move the market toward allocative efficiency.

Understanding the Question

This is a multiple-choice question asking which of four options "might help achieve allocative efficiency." The question does not specify a particular market failure context, so we must consider each option in general terms and decide whether it could, in principle, move a market closer to P = MC. The options are: differentiated products (a feature of monopolistic competition), government subsidies (a policy tool), monopsony (a market structure with a single buyer), and supernormal profits (a profit level above normal).

Approach

We evaluate each option against the condition for allocative efficiency (P = MC). For each, we ask: does this option tend to push price toward marginal cost, or does it create a divergence? The correct answer is the one that can correct a market failure that prevents P = MC.

Step-by-Step Reasoning

Option A: Differentiated products. Differentiated products are a feature of monopolistic competition and, to some extent, oligopoly. Firms with differentiated products have some market power, meaning they face a downward-sloping demand curve. A profit-maximising firm in such a market sets output where MR = MC, and then charges a price above MC (since the demand curve is above MR at that quantity). This results in P > MC, which is a sign of allocative inefficiency (underproduction from society's point of view). Therefore, differentiated products do not help achieve allocative efficiency; they are a source of inefficiency.

Option B: Government subsidies. A subsidy is a payment from the government to producers (or consumers) that lowers the cost of production or the price to consumers. Consider a market with a positive externality in consumption (e.g., education or vaccinations). The marginal social benefit (MSB) is greater than the marginal private benefit (MPB). In a free market, the quantity traded is where MPB = MPC, which is less than the socially optimal quantity where MSB = MSC. A subsidy can lower the price to consumers, increasing the quantity demanded toward the socially optimal level. By aligning the price closer to the marginal social cost, a subsidy can help achieve allocative efficiency. This is a standard textbook example of government intervention to correct market failure.

Option C: Monopsony. Monopsony is a market structure with a single buyer. A monopsonist has market power in the input market (e.g., a single employer in a labour market). The monopsonist can restrict the quantity purchased to drive down the price (wage). This leads to a situation where the price (wage) is below the marginal value of the good (marginal revenue product), creating allocative inefficiency. Monopsony does not help achieve allocative efficiency; it is a source of market failure.

Option D: Supernormal profits. Supernormal profit (also called economic profit or abnormal profit) is profit above the minimum required to keep a firm in the industry (normal profit). In perfect competition, supernormal profits attract new entrants, which increases supply, drives down price, and eliminates the supernormal profit in the long run. However, the presence of supernormal profit itself is not a mechanism for achieving allocative efficiency. In monopoly, supernormal profits can persist due to barriers to entry, and the price is above MC, indicating allocative inefficiency. Supernormal profits do not help achieve allocative efficiency; they are often a symptom of market power and inefficiency.

Therefore, only option B, government subsidies, can help achieve allocative efficiency by correcting a positive externality.

Key Takeaways

• Allocative efficiency is achieved when P = MC.
• Market failures (externalities, public goods, imperfect competition) cause P ≠ MC.
• Government intervention, such as subsidies, taxes, or regulation, can correct market failures and move the market toward allocative efficiency.
• Differentiated products, monopsony, and supernormal profits are associated with market power and inefficiency, not with achieving allocative efficiency.

Common Mistakes

• Confusing allocative efficiency with productive efficiency. Productive efficiency is producing at the lowest cost (minimum AC), while allocative efficiency is producing the right mix of goods (P = MC).
• Thinking that any government intervention always helps. Some interventions (e.g., price controls, poorly designed subsidies) can cause government failure and worsen allocative efficiency.
• Assuming that supernormal profits in perfect competition are a problem. In perfect competition, supernormal profits are temporary and signal resources to move into that industry, which is part of the allocative mechanism. However, the question asks what "might help achieve" allocative efficiency, and supernormal profits are not a policy tool.

Things to Be Careful About

• Read the question carefully: "What might help achieve allocative efficiency?" The word "might" suggests a possibility, not a certainty. A subsidy can help in the right circumstances (correcting a positive externality), but it is not guaranteed to always improve efficiency.
• Do not overthink: the question is testing a standard textbook point about government intervention to correct market failure.
• Remember the condition P = MC. For each option, ask whether it tends to make P closer to MC or further away.