AP Syllabus focus: ‘A firm can be a perfect competitor in the labor market even if it is imperfectly competitive in output markets.’
In many real industries, firms sell output with some market power but hire workers in broad labor markets. This page explains how hiring decisions change when the wage is competitive but output is not.
Core idea: competitive input market, imperfect output market
A firm can be a price taker in the labor market while being a price maker (or price searcher) in the output market. The key implication is:
The wage is determined by the market, so the firm treats the wage as given.
The revenue created by an extra worker depends on the firm’s output market structure, so it is not necessarily based on output price.
What “competitive labor market” means here
Wage taker — a firm that can hire any quantity of labor at the market wage and cannot influence that wage.
Because the firm is a wage taker, hiring an additional worker does not require raising the wage to attract that worker.
Marginal resource cost stays wage-based
In a competitive labor market, the firm’s marginal resource cost (MRC) of labor is constant at the market wage:
MRC of labor is the additional cost of hiring one more worker.
If the wage is , then each additional worker adds to total labor cost (holding everything else constant).
This keeps the firm’s input cost side “competitive” even if its product market is not.
Marginal revenue product depends on the output market
The firm’s labor demand is based on the extra revenue generated by hiring one more worker. Under imperfect competition in the output market, the extra output sold may require lowering price on additional units, so marginal revenue is not equal to price.
Marginal revenue (MR) — the additional revenue from selling one more unit of output.
The connection between an extra worker and revenue runs through MR rather than the output price.
= additional revenue from one more worker (dollars per worker)
= marginal product of labor, extra output from one more worker (units of output per worker)
= marginal revenue, extra revenue from one more unit sold (dollars per unit)
Because an imperfect competitor typically has MR < P, this implies (for a given ) that is smaller than it would be under perfect competition in the output market.
Demand (average revenue) and marginal revenue are plotted for an imperfectly competitive firm, with lying below the demand curve. The diagram visually reinforces why selling additional units requires lowering price, so the marginal gain in revenue is smaller than the price received. Source
The hiring rule: set wage equal to MRP
Profit-maximizing hiring compares the extra benefit of a worker to the extra cost:
Hire labor up to the quantity where .
The graph shows the firm’s labor demand curve as the marginal revenue product of labor () intersecting a horizontal wage line, illustrating the profit-maximizing condition . It also contrasts employment when the firm has output-market power (lower ) versus when it is perfectly competitive in output (higher labor demand). Source
If , the worker adds more revenue than cost, so hiring increases profit.
If , the worker adds less revenue than cost, so hiring reduces profit.
This looks like the competitive hiring rule, but the crucial difference is that is calculated using MR (not the product price) when output markets are imperfect.
Implications for the firm’s labor demand curve
The firm’s labor demand curve is its curve:
It slopes downward because diminishing marginal returns typically cause to fall as more workers are hired.
Under imperfect output competition, it is generally lower than it would be under perfect output competition (since MR is lower than price at the relevant output levels).
Changes in the firm’s output demand that affect MR will shift and therefore shift labor demand.
Reading the combined-market story correctly
When you see “competitive labor market with imperfect output market,” keep these distinctions clear:
Input price side: wage is market-determined; the firm is a wage taker; .
Input benefit side: extra revenue comes from selling extra output where the firm faces a downward-sloping product demand; therefore MR matters, making depend on market power.
FAQ
A higher mark-up typically reflects lower $MR$ relative to $P$ at the margin.
With a lower $MR$, each unit of $MP_L$ converts into less extra revenue, reducing $MRP_L$ and shifting the firm’s labour demand left.
Often yes, because $VMP_L = MP_L \times P$ while $MRP_L = MP_L \times MR$, and typically $MR < P$.
However, the size of the gap depends on the elasticity of product demand and the firm’s pricing position.
Anything that raises $MRP_L$ at each employment level can increase hiring.
For example, stronger product demand can raise $MR$ over relevant output ranges, increasing $MRP_L$ and shifting labour demand right.
Using $P$ implicitly assumes the firm can sell extra output without reducing marginal revenue.
In imperfect competition, $MR$ reflects the revenue effect of expanding sales (including any price reduction), so $P$ overstates the marginal benefit of labour.
When demand is more elastic, $MR$ is closer to $P$; when demand is less elastic, $MR$ is much lower (and can be negative).
So, more elastic demand tends to raise $MRP_L$ (holding $MP_L$ constant), increasing the incentive to hire labour.
Practice Questions
(2 marks) Explain why a firm can be a wage taker in the labour market even if it has market power in the output market.
Identifies that the wage is set by a competitive labour market and the firm cannot influence it (1).
Distinguishes this from the output market, where the firm faces a downward-sloping demand curve and can affect price (1).
(5 marks) A firm sells its output in an imperfectly competitive market and hires labour in a perfectly competitive labour market at wage . Explain how the firm determines its profit-maximising quantity of labour, referring to , , and .
States the hiring condition (1).
Correctly defines or describes as the additional revenue from one more worker (1).
Explains that depends on both and (1).
Notes that in imperfect competition , affecting (1).
Applies the decision rule: hire more if , hire less if (1).
