Ask whether resources are well allocated and who can access essentials.
Allocative efficiency means resources generate the greatest net benefit to society. In the usual model with falling marginal social benefit and rising marginal social cost, the interior social optimum is where MSB = MSC. Equity concerns fairness in the distribution of essential goods and services. An efficient outcome need not be equitable. In these syllabuses, inequity is a distributional issue, not itself market failure.
- Efficiency
- Allocative efficiency means using resources to create the greatest net social benefit: benefits to society minus opportunity costs. Market failure occurs when the market allocates resources inefficiently.
- The extra unit
- Marginal means one extra unit. Marginal social benefit (MSB) is its benefit to everyone affected; marginal social cost (MSC) is its full opportunity cost to society. Social includes people outside the purchase as well as buyers and sellers.
- Equity
- Equity concerns fairness in access to essential goods and services. An efficient output can still be unaffordable for some people; inequity alone is a distributional issue, not market failure in this syllabus.
Use the marginal comparison
Below the optimum
The social optimum is the output giving the greatest net social benefit. If another unit adds more benefit than cost (MSB > MSC), producing it raises that benefit. If its cost exceeds its benefit, leaving it unproduced is better.
Model conditions
With falling MSB and rising MSC crossing at a feasible quantity, MSB = MSC identifies the optimum. If only whole packages can be chosen, compare the available increments; exact equality need not occur.
Distribution
An efficient market allocation reflects ability to pay. Targeted subsidies or public provision can pursue fairness, but eligibility, coverage and resources still need evaluation.
| Question | What to examine |
|---|---|
| Efficiency | Social marginal benefits/costs and resource allocation |
| Equity | Who can access essential goods, need and fairness |
| Policy effectiveness | Whether the mechanism improves the stated objective after costs |
Worked example: An efficient service that some cannot afford
A service operates at the output where the social benefit of the last unit equals its social cost. Some low-income households cannot afford access.
- The stated equality identifies the efficient output under the usual marginal-curve assumptions.
- It does not establish fairness: demand reflects ability to pay as well as willingness to buy.
- Unaffordable essential access can justify an equity objective even without a demonstrated allocation failure.
- Targeted assistance must be assessed for access, funding and any effect on the quantity or quality supplied.
Watch out for this
An unfair outcome proves that the market is allocatively inefficient.
Efficiency and equity are different tests. Identify an allocation failure separately rather than renaming inequity as market failure.
Check your understanding
A policy makes access fairer but increases resource costs more than total benefits. What follows?
- It must improve allocative efficiency.
- It can improve equity while reducing efficiency.
- It cannot improve any government objective.