7.3 Efficiency and market failure

Economic efficiency seeks the greatest attainable benefit from scarce resources. A healthcare system, for example, cannot meet every possible demand; efficiency asks how to secure the maximum health gain from available resources.

The criteria are independent. A firm can produce at minimum AC yet restrict output so price exceeds MC; it is productively efficient but not allocatively efficient. An economy can be on its PPC at many output mixes, only one of which may match preferences.

If marginal benefit/price exceeds marginal cost, consumers value another unit more than the resources it uses, so output should rise. If marginal cost exceeds marginal benefit, output should fall. At equality, no extra unit creates a net marginal welfare gain.

A profit-maximising firm chooses MR = MC, which is not generally allocatively efficient when demand slopes down because MR lies below price. Regulation or public ownership may set P = MC, but if that price is below AC the provider can make a loss and need financing.

Both criteria hold only when the chosen output is simultaneously at minimum AC and at the relevant marginal-benefit/marginal-cost equality. A lower AC at unchanged output improves productive efficiency but not allocative efficiency if P remains above MC.

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.

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.

At the socially efficient output, MSB = MSC. When private prices omit a cost or benefit, private equilibrium can create overproduction or underproduction and a deadweight welfare loss; failure may be partial rather than the market producing nothing.

If pollution costs imposed on neighbours are absent from a factory's private costs, market output can exceed the socially efficient quantity: the transaction's full costs are not reflected in price.

Diagnose in three links: identify the missing or distorted signal; show how it separates private from social marginal incentives; state the resulting over- or under-allocation. The same symptom, such as low vaccination, can arise from an external benefit, information gap or market power.

A guaranteed price that creates unsold stocks is government intervention failure, not evidence that an unregulated market caused the original distortion. Diagnosis must precede any remedy.