marginal revenue product (MRP) theory: definition and calculation of marginal revenue product

Labour Market Forces & Government Intervention: MRP Theory

What is Marginal Revenue Product (MRP)?

MRP is the extra revenue a firm earns by hiring one more unit of labour. Think of it as the “bonus money” a worker brings to the business.

Mathematically: \$\text{MRP} = \text{MP} \times \text{MR}\$

  • MP – Marginal Product (extra output from one more worker)

  • MR – Marginal Revenue (price of the extra output)

Why MRP Matters

🔍 Firms decide how many workers to hire by comparing MRP to the wage. If MRP > wage, hiring more workers increases profit. If MRP < wage, hiring reduces profit.

📈 In a competitive market, firms hire until MRP equals the wage, ensuring resources are used efficiently.

Calculating MRP – Step by Step

  1. Determine the Marginal Product (MP) of labour.

    Example: If the 4th barista adds 10 cups of coffee per hour, MP = 10 cups.

  2. Find the Marginal Revenue (MR).

    Example: If each cup sells for \$2, MR = \$2.

  3. Multiply: \$\text{MRP} = \text{MP} \times \text{MR} = 10 \times 2 = \\$20\$\$ per hour.

  4. Compare MRP to the hourly wage. If wage < $20, hire the worker.

Example: Coffee Shop Hiring Baristas

Worker #Output (cups/hr)MP (cups)Price ($/cup)MR ($)MRP ($/hr)Wage ($/hr)
13030$2$2$60$50
25525$2$2$50$55
37015$2$2$30$45

🔎 Notice how the 3rd barista’s MRP (\$30) is less than the wage (\$45). The shop should stop hiring after the 2nd barista.

Exam Tips & Quick Facts

??

Key point: MRP = MP × MR. Remember to calculate MP first (difference in output), then multiply by the price (MR).

??

When to hire? Hire until MRP ≥ wage. If MRP < wage, stop hiring.

??

Common exam trick: They may give you total output and ask for MP. Use the difference between successive workers.

??

Remember: In a perfectly competitive labour market, firms hire until MRP = wage. In a monopsony, the firm may hire less because it faces a higher marginal cost of labour.

📌 Tip: Draw a quick table or graph to visualise MRP and wage comparison. It saves time and reduces errors.

Quick Summary

  • MRP tells us the extra revenue from hiring one more worker.

  • Calculate MP (extra output) and MR (price of that output).

  • Compare MRP to the wage to decide on hiring.

  • Use tables or diagrams to show the decision process clearly.