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EC311 · Intermediate Microeconomics

EC311 / TOPIC 37

9.2 Monopsony, minimum wages and bargaining

Why does a monopsonist pay a lower wage and hire fewer workers than a competitive market?

A buyer facing upward factor supply has ME above wage, so it sets ME=MRPL and reads wage from supply.

Follow the cause and effect

  1. Write total labor expenditure w(L)L and derive ME.

  2. Set ME=MRPL for Lm, then use supply for wm.

  3. With a minimum wage, build piecewise ME and inspect the kink.

The model you are using

KEY MODEL
w=10+L
ME=10+2L
MRPL=70−L

Conditions for this model

Uniform wage, continuous labor supply and the specified marginal revenue product schedule.

The exam trap

Do not read wages from ME, and do not assume a minimum wage always cuts monopsony employment.

Connect the reasoning to the graph

What changes

  • ME lies above labor supply; ME=MRPL determines L, then project to supply for w.

What stays fixed

Uniform wage, continuous labor supply and the specified marginal revenue product schedule.

Keep these conditions throughout the comparison; change only what the case above specifies.

What to inspect

With a minimum wage, build piecewise ME and inspect the kink.

Compare before and after, and locate the conclusion on the graph.

5 MINUTES · TRANSFER THE IDEA

Can you explain it without the lesson?

Draw a minimum-wage range that raises both wage and employment relative to monopsony.

Lesson references

  • Pindyck & Rubinfeld, Microeconomics, 9th Global ed., pp. 400, 561
  • Original minimum-wage piecewise expenditure calculation
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