7.3 Efficiency and market failure

Productive efficiency occurs when output is produced at the lowest possible average cost, often where a firm operates at minimum AC. Allocative efficiency occurs when output matches what consumers value at the margin, represented by P = MC in a competitive model.

A market can satisfy one condition without the other. A monopoly may exploit economies of scale and be productively efficient yet restrict output so price exceeds marginal cost.

If a firm produces at the bottom of its average-cost curve but charges a price above marginal cost, it minimises cost per unit but does not allocate resources according to marginal willingness to pay.

“Efficient” is incomplete unless you specify productive, allocative or another criterion; minimum average cost is not the same as P=MC.

The usual productive-efficiency condition is output at minimum average cost. The usual allocative-efficiency condition is price equal to marginal cost, because the value of the last unit equals the resource cost.

These are model conditions, not universal laws. Externalities require social rather than private marginal cost or benefit; public goods and information problems may prevent the simple market result.

If a factory’s minimum AC occurs at 1,000 units but its price is above MC at that output, it is productively efficient but allocatively inefficient in the basic model.

Do not apply P=MC mechanically when external costs, market power or non-price allocation means the relevant social curves differ from private curves.

An allocation is Pareto efficient when there is no feasible change that benefits at least one person without harming anyone else. It is a criterion about possible improvements, not a judgement that the outcome is fair.

Many unequal allocations can be Pareto efficient because changing them would hurt someone. Pareto efficiency also says nothing about who has power, basic needs or equal opportunities.

A redistribution from a wealthy person to a poor person may improve welfare but fail the strict Pareto test because the donor is worse off, even if society regards the change as fair.

Pareto efficient does not mean socially optimal, equal or morally desirable; it only rules out a particular kind of mutually non-harmful improvement.

Dynamic efficiency concerns whether firms and markets improve products, processes and productive capacity over time, often through investment, research and development and learning.

A temporary loss of static allocative efficiency may be defended if retained profits finance innovation. The claim must be tested: market power can provide resources for R&D, but it can also weaken the pressure to innovate.

A patent-protected firm may charge above marginal cost today while investing in a lower-cost production method that becomes available later. Whether this is dynamically efficient depends on the size and persistence of the innovation.

Dynamic efficiency is not simply “any investment”, and a monopoly is not automatically dynamically efficient; compare innovation benefits with exclusion and pricing costs.

Market failure occurs when the market allocation of resources is inefficient, so the social benefits and costs of output are not correctly reflected in private decisions.

The result may be too much, too little or the wrong composition of output. Externalities, public goods, information gaps, market power and missing markets are common mechanisms; identify which one prevents the price system from coordinating resources.

If a factory’s pollution harms neighbours without appearing in its costs, the market can produce more than the socially efficient quantity.

Market failure does not mean the market produces zero output or that every government intervention improves welfare; compare the likely policy failure too.

Market failure can arise from external costs or benefits, non-rival or non-excludable goods, asymmetric information, market power or a missing market.

The diagnosis determines what is unpriced or misallocated. A Pigouvian tax may address a measurable external cost; information disclosure addresses knowledge; competition policy addresses market power. The same symptom can have different causes.

A shortage of vaccinations may reflect an external benefit rather than a monopoly. A single dominant supplier may instead restrict output even when no spillover exists.

Do not label every high price “market failure”, and do not choose a subsidy before explaining which social marginal curve is missing from the market decision.