The Minimum Wage in Two Market Structures

You’ll be able to

Predict the effect of a binding minimum wage in a competitive labor market
Explain why a minimum wage can raise employment under monopsony
Identify what determines the size of the employment effect

In a competitive market, a binding minimum reduces employment

A minimum wage above the competitive equilibrium creates a surplus of labor: quantity supplied exceeds quantity demanded. Employment falls to the quantity demanded at the higher wage, and unemployment appears. Those still employed earn more; those who lose or never get jobs earn nothing. This is the standard result and it depends on the market being competitive.

Under monopsony, the same policy can raise employment

A monopsonist hires fewer workers than the efficient number, because MFC exceeds the wage. Impose a minimum wage between the monopsony wage and the competitive wage and the employer can no longer lower the wage by hiring fewer people — the wage is now fixed, so MFC equals that wage over the relevant range. The firm hires where MRP meets that flat MFC, which is more workers than before. So the minimum wage raises both pay and employment. This is the most counterintuitive result in the unit and a recurring free-response subject.

The two outcomes

competitive market: binding minimum → wage ↑, employment ↓, labor surplus · monopsony (minimum between monopsony and competitive wage): wage ↑, employment ↑

Same policy, opposite employment effect. The market structure is what decides it, which is why questions always specify the structure.

What determines the size of the effect

In a competitive market the employment loss depends on the elasticity of labor demand. Inelastic demand — few substitutes for the workers, labor a small share of total cost — means a small employment loss. Elastic demand — easily automated work, labor a large cost share — means a large one. So the empirical disagreement about minimum wages is largely a disagreement about elasticity and about how competitive low-wage labor markets actually are.

Worked example

A monopsonist currently employs 30 workers at $12, where MRP is $20. A minimum wage of $16 is imposed, and 45 workers are willing to work at $16. Explain what happens.

1.Before the law, the firm hires 30 where MRP = MFC, paying only $12 — well below the $20 MRP.
2.With a $16 minimum, the firm can no longer pay less by hiring fewer, so MFC becomes a flat $16.
3.It now hires where MRP = $16, which is beyond 30 workers.
4.Since 45 are willing to work at $16, and MRP still exceeds $16 up to some point past 30, employment rises.

Answer: Both the wage and employment rise. The minimum wage removed the firm's ability to suppress the wage by restricting hiring, so it expands employment toward the efficient level — the opposite of the competitive-market prediction.

Watch out

The monopsony result holds only for a minimum wage between the monopsony wage and the competitive wage. Set it above the competitive wage and employment falls, exactly as in a competitive market. State the range or the answer is only half right.

Checkpoint

A binding minimum wage in a perfectly competitive labor market causes:

Checkpoint

A minimum wage set between the monopsony wage and the competitive wage causes employment to:

Checkpoint

In a competitive labor market, the employment loss from a minimum wage is smallest when labor demand is:

On the exam

Read the market structure before answering any minimum-wage question. "Perfectly competitive labor market" and "the sole employer in the region" call for opposite employment answers, and the wording is the only signal.

Answer the 3 checkpoints as you read.