Topic 5.1 Notes – Introduction to Factor Markets

1. What Factor Markets Are

A factor market (resource market) is where firms hire the factors of production:

• Labor → paid wages
• Capital (tools, machines) → paid interest
• Land (natural resources) → paid rent
• Entrepreneurship → earns profit

In the circular flow model,

• Households supply factors
• Firms demand factors

Factor prices send signals:

• High wages attract more workers.
• High interest rates encourage saving and capital investment.
• Firms respond to these prices when deciding how many resources to hire.

This connects directly to real-world examples. When demand for tech products surged in the 2010s, wages for software engineers rose. During housing booms, construction wages rise. The resource market reacts to the product market.

Derived Demand

Demand for a factor is derived from the demand for the final good.

If consumers want more electric vehicles → firms produce more EVs → they demand more engineers and lithium (land/resource).

Important link:

• If the price of the output rises, the value of each worker’s output rises.
• That increases the firm’s willingness to hire.

Firms hire resources because those resources generate revenue.

2. The Demand and Supply of Labor

We focus mostly on labor markets in AP Micro.

Labor Demand (Downward Sloping)

Start with the labor market graph below. The vertical axis shows the real wage and the horizontal axis shows hours worked or quantity of labor.

Labor market with supply and demand

The labor demand curve slopes downward.

Labor demand slopes downward because:

1. Law of diminishing marginal returns
   As more workers are added to fixed capital like a factory, each additional worker adds less extra output.
2. Higher wages increase the cost of hiring, so firms hire fewer workers.

If wage rises → quantity of labor demanded falls.
If wage falls → quantity demanded rises.

This is driven by productivity and cost.

Labor Supply (Upward Sloping)

On the same graph, the labor supply curve slopes upward.

Upward-sloping labor supply curve

Labor supply slopes upward because:

• Higher wages make work more attractive relative to leisure.
• More individuals enter the labor force.

If wage rises → quantity of labor supplied rises.
If wage falls → quantity supplied falls.

Labor Market Equilibrium

Equilibrium occurs at the point where the labor demand and labor supply curves intersect.

Labor market equilibrium

At this point, quantity demanded = quantity supplied.

• Wage above equilibrium → surplus of labor, which means unemployment.
• Wage below equilibrium → labor shortage.

The equilibrium wage is the factor price that balances incentives for firms and households.

3. Marginal Product and Marginal Revenue Product

Firms care about how much revenue each worker adds.

Total Product (TP)

Total output produced with a given number of workers.

Marginal Product (MP)

Change in output from hiring one more worker.

$$MP = \Delta TP$$

Due to diminishing marginal returns, MP eventually falls as more workers are added.

Marginal Revenue Product (MRP)

This is the most important concept in this topic.

$$MRP = MP \times P$$

• MP = extra output
• P = price of output

MRP tells you the extra revenue from one more worker.

If output price increases → MRP increases → labor demand shifts right.

Because MP diminishes, MRP also diminishes, which explains why the labor demand curve slopes downward.

4. Marginal Resource Cost and the Hiring Rule

Marginal Resource Cost (MRC)

MRC = cost of hiring one more unit of a resource.

In a perfectly competitive labor market:

• $MRC = \text{wage}$

For capital, MRC reflects the user cost of capital (interest + depreciation).

Profit-Maximizing Hiring Rule

Firms hire where:

$$MRP = MRC$$

Think of it exactly like the output rule $MR = MC$.

• If $MRP > MRC$ → hire more.
• If $MRP < MRC$ → hire fewer.
• Stop at equality.

Example Calculation

Suppose:

• Output price = 8 dollars
• Wage = 40 dollars

If the 4th worker has:

• $MP = 6$

Then:

$$MRP = 6 \times 8 = 48$$

Since 48 > 40 → hire that worker.

If the 5th worker has:

• $MP = 4$

$$MRP = 4 \times 8 = 32$$

Now 32 < 40 → do not hire the 5th worker.

The firm hires 4 workers.

On AP-style questions, they’ll often give you a table with TP and wage. You calculate MP, then MRP, then compare to wage. The last worker where $MRP \geq MRC$ is the profit-maximizing quantity.

Big Picture

Factor markets and product markets are connected.
When demand for a product rises → output price rises → MRP rises → labor demand increases → wages increase.

Factor prices provide incentives and guide how resources are allocated in the economy.