Monopsony vs Minimum Wage
Monopsony and Minimum Wage are related concepts in AP Economics that students often mix up. A monopsony is a market structure with a single buyer and many sellers, giving the buyer market power. A minimum wage is a legal price floor on wages, the lowest amount employers may legally pay workers. Here is how they compare side by side.
In a monopsony, the single buyer can influence the price of the product by changing the quantity it purchases. This allows the monopsonist to pay a lower price than in a competitive market. Monopsony power can arise in factor markets, such as a large employer in a small town.
Set above the market wage, it can raise pay for some workers but may cause a surplus of labor (unemployment) by reducing hiring. Its real-world employment effects are debated and depend on how high it is set.
Monopsony vs Minimum Wage: A Market Structure and a Policy
| Monopsony | Minimum Wage | |
|---|---|---|
| Category of thing | A structure of the labor market, one buyer facing many sellers | A law applied on top of whatever structure already exists |
| Who sets the wage | The employer, by choosing a point on the labor supply curve | The government, as a floor the employer may not go under |
| Curve you must draw for it | Marginal factor cost, above and steeper than the labor supply curve | A horizontal line at the floor that replaces the supply curve up to the quantity supplied |
| Wage compared with MRP | Below MRP at the hiring level, a gap known as monopsonistic exploitation | Depends on the market it lands in, and it can still sit below MRP in a monopsony |
| Effect on employment | Employment below the competitive level | Falls in a competitive market, and can rise in a monopsony when the floor sits between the monopsony wage and the competitive wage |
| When it bites | Always, if the firm really is the only buyer | Only when set above the wage that would otherwise be paid |
A wage floor can raise employment, and here is the arithmetic that shows it
Take a single employer in a town where labor supply is W = 2 + 2L and the marginal revenue product of labor is MRP = 26 - 2L, with W in dollars an hour. Because hiring one more worker raises the wage paid to everyone, marginal factor cost is 2 + 4L, above the supply curve. The firm hires where MFC meets MRP, at L = 4, then pays what the supply curve asks at that quantity, $10. MRP at that worker is $18, so the gap between what the last worker adds and what she is paid is $8. A competitive market with the same curves would settle where supply meets MRP, at L = 6 and a wage of $14. Now impose a floor of $14. The firm can no longer push the wage down by hiring less, so marginal factor cost is a flat $14 up to 6 workers, and it hires until MRP equals $14, which is L = 6. The wage rises from $10 to $14 and employment rises from 4 to 6, with no unemployment, since exactly 6 workers want jobs at $14. Set the floor at $20 instead and the firm hires where MRP = $20, at L = 3, while 9 workers want jobs. Employment now sits below even the unregulated monopsony level, with 6 workers unemployed.
Marginal factor cost is the wedge, and the floor works by flattening it
A firm in a competitive labor market can hire as many workers as it likes at the going wage, so one more worker costs exactly that wage and marginal factor cost equals the wage. A monopsonist faces the market's upward-sloping supply curve, so hiring one more means paying more to everyone already there. Using the same supply curve, moving from 3 workers to 4 raises the wage from $8 to $10. The wage bill goes from $24 to $40, so that fourth worker costs $16, not $10: her own $10 plus $2 more for each of the three already employed. The smooth line 2 + 4L is the continuous version of that same step and reads $18 at exactly four workers, so on either reading the true cost sits far above the $10 wage. That cost is what the firm weighs against MRP, which is why it stops hiring early and why the wage lands below MRP. A wage floor changes the comparison. Over the range where the floor binds, every worker costs the same posted amount, so marginal factor cost equals the floor and the penalty for hiring one more vanishes. The policy does not shame the employer into paying more. It removes the mechanism that made holding back profitable, which is why the employment effect can point the opposite way from the competitive case.
The market structure in the stem decides the sign of your answer
Two questions can print the same policy and expect opposite answers. If the stem says perfectly competitive labor market and the floor sits above equilibrium, the required answer is a surplus of labor: quantity supplied exceeds quantity demanded, employment falls, and you shade the horizontal gap between the curves at the floor. If the stem describes a company town, a single hospital hiring nurses, or any other single buyer, the answer depends on where the floor sits relative to the competitive wage. Between the monopsony wage and the competitive wage, both the wage and employment rise and there is no unemployment gap to shade. Above the competitive wage, employment falls again and the surplus reappears. Read the structure first, locate the floor second, answer third. On the diagram, label supply, marginal factor cost above it, and MRP sloping down, then draw the floor as a horizontal line replacing supply up to where the two meet. Leaving MFC off the diagram is the fastest way to lose the point, because without it nothing justifies the hiring quantity you chose.
Frequently asked questions
Does a minimum wage always reduce employment?
A minimum wage reduces employment in a competitive labor market when it is set above the equilibrium wage, because firms move up a downward-sloping labor demand curve while more workers offer to work. In a monopsony the result can reverse. A floor placed between the wage the single employer would pay and the competitive wage raises the wage and the number hired together, since it removes the rising marginal factor cost that made the employer hold back. Push the floor far enough above the competitive wage and employment falls again.
Why does a monopsonist pay a wage below MRP?
A monopsonist has to raise the wage for every worker in order to attract one more, so the true cost of that extra worker, marginal factor cost, exceeds the wage. The firm hires where marginal factor cost equals marginal revenue product, then pays only what the supply curve requires at that quantity, which is lower. The gap between MRP and the wage at the hiring level is sometimes called monopsonistic exploitation, and in the worked example above it comes to $8 an hour.
Live Factor Markets graph. Drag the curves, or open the full version.
Live Supply and Demand graph. Drag the curves, or open the full version.
Related comparisons
Get AP Econ exam tips in your inbox
Occasional emails with study tips, new interactive graphs, and exam-season reminders. Free, no spam.
No spam. Unsubscribe anytime. Read our privacy policy.
Keep track of what you have studied
A free EconLearn account adds progress tracking, your quiz history, and achievements. Studying here is free either way, and there is nothing to pay for as a student.
Create a free accountAlready have one? Sign in
Last updated