Changes in Factor Demand and Factor Supply - AP Microeconomics Study Guide

Core Concepts & Learning Goals

This chapter explores the dynamics of factor markets, focusing specifically on the market for labor. Just like in product markets, the forces of supply and demand determine the price (the wage rate) and quantity (the level of employment). The core idea is that changes in underlying economic conditions will cause the demand for labor or the supply of labor to change, leading to new equilibrium wages and employment levels.

After studying this topic, you will be able to explain how changes in various determinants shift the labor demand and labor supply curves, and how these shifts impact the equilibrium wage rate and the quantity of labor hired in a factor market.

Key Concepts Breakdown

1. Understanding Labor Demand

The demand for labor is a derived demand. This is a critical concept meaning that a firm's demand for a worker is derived from the demand for the product that the worker helps to produce. A firm hires workers because they contribute to producing a good or service that can be sold for revenue. The labor demand curve is downward-sloping because as the wage rate falls, firms are willing and able to hire more workers.

2. Determinants of Labor Demand

Changes in factors other than the wage rate can cause the entire labor demand curve to shift. A shift to the right indicates an increase in demand, while a shift to the left indicates a decrease. The primary determinants are:

• Output Price: The price of the good or service the labor produces. If the price of the product increases, each worker becomes more valuable to the firm because the revenue they generate increases. This raises the Marginal Revenue Product (MRP), which is the additional revenue a firm earns from hiring one more worker. An increase in the output price shifts labor demand to the right. A decrease in the output price shifts it to the left.

• Productivity of the Worker: The output per worker. If workers become more productive (due to new technology, better training, or more capital), they produce more output in the same amount of time. This increases their Marginal Product (MP), which in turn increases their MRP. An increase in productivity shifts the labor demand curve to the right. A decrease in productivity shifts it to the left.

3. Understanding Labor Supply

The supply of labor represents the number of hours individuals are willing and able to work at various wage rates. The labor supply curve is typically upward-sloping. This reflects the trade-off between work and leisure; as the wage rate increases, the opportunity cost of leisure rises, incentivizing more people to offer their labor to the market.

4. Determinants of Labor Supply

Changes in non-wage factors can cause the entire labor supply curve to shift. A shift to the right indicates an increase in the supply of labor, while a shift to the left indicates a decrease. Key determinants include:

• Immigration and Migration: An increase in the number of workers available due to immigration or migration into a region will shift the labor supply curve to the right.

• Education and Training: If a job requires more education or training, the supply of qualified workers may decrease, shifting the supply curve to the left. Conversely, programs that make training more accessible can shift supply to the right.

• Working Conditions: Improvements in the safety or pleasantness of a job make it more attractive, shifting the labor supply curve to the right. Worsening conditions will shift it to the left.

• Age Distribution and Population: A growing population or an increase in the proportion of the population in its prime working years will increase the supply of labor, shifting the curve to the right.

• Availability of Alternative Options: If wages or opportunities in other professions become more attractive, some workers will leave this market, shifting the labor supply curve to the left.

• Preferences for Leisure: A societal shift in preference toward more leisure time and less work will decrease the supply of labor, shifting the curve to the left.

• Cultural Expectations: Changes in cultural norms, such as increased participation of women in the workforce over the last several decades, can significantly shift the labor supply curve to the right.

Summary of Market Shifters

Graphical Analysis (Text-Only)

We can analyze changes in the labor market using a standard supply and demand graph.

• Axes Declaration:

  • Vertical axis: Wage Rate (W)

  • Horizontal axis: Quantity of Labor (L)

• Curve Specifications:

  • Labor Demand (D_L): A downward-sloping curve, showing the inverse relationship between the wage rate and the quantity of labor firms demand.

  • Labor Supply (S_L): An upward-sloping curve, showing the positive relationship between the wage rate and the quantity of labor individuals are willing to supply.

• Equilibrium and Shifts:

  1. Initial Equilibrium: The market is initially in equilibrium where the D_L and S_L curves intersect. This point determines the equilibrium wage (W_e) and the equilibrium quantity of labor (L_e). At W_e, the quantity of labor demanded equals the quantity of labor supplied.

  2. Scenario A: An Increase in Labor Demand. Suppose the productivity of workers increases.

     • The D_L curve shifts to the right to become D_L2. The S_L curve remains unchanged.

     • At the original wage W_e, there is now a shortage of labor (quantity demanded > quantity supplied).

     • Firms compete for the available workers, bidding up the wage.

     • The market reaches a new equilibrium at the intersection of D_L2 and S_L. The new equilibrium wage (W_e2) is higher than W_e, and the new equilibrium quantity of labor (L_e2) is greater than L_e.

  3. Scenario B: An Increase in Labor Supply. Suppose there is a large wave of immigration.

     • The S_L curve shifts to the right to become S_L2. The D_L curve remains unchanged.

     • At the original wage W_e, there is now a surplus of labor (quantity supplied > quantity demanded).

     • The excess supply of workers puts downward pressure on the wage.

     • The market reaches a new equilibrium at the intersection of D_L and S_L2. The new equilibrium wage (W_e2) is lower than W_e, and the new equilibrium quantity of labor (L_e2) is greater than L_e.

Step-by-Step Example

Let's analyze the impact of a new popular video game on the market for video game developers.

• Scenario: A gaming company releases a new title that becomes an international bestseller, dramatically increasing the price and sales of the game. What happens in the labor market for game developers?

• Step 1: Identify the Market and the Change.

  • The market is the factor market for video game developers.

  • The change is an increase in the output price of the product these developers create.

• Step 2: Determine Which Curve Shifts and Why.

  • The price of the output is a key determinant of labor demand.

  • Because the game's price and popularity have increased, the marginal revenue product (MRP) of each developer has risen. Each developer now generates more revenue for the company than before.

  • This causes the labor demand curve (D_L) for game developers to shift to the right. The labor supply curve is not directly affected by the game's price.

• Step 3: Analyze the Impact on Equilibrium Wage and Quantity.

  • The rightward shift of the demand curve creates a shortage of developers at the original equilibrium wage.

  • Gaming companies must now compete more intensely to hire the developers they need, offering higher salaries and better benefits.

  • This upward pressure on wages continues until a new equilibrium is reached. The new equilibrium will feature a higher equilibrium wage and a higher equilibrium quantity of game developers employed.

AP Exam Tips & Common Pitfalls

• [FRQ Task]: You will frequently be asked to analyze a scenario, identify the correct curve shift in a factor market, and explain the resulting change in the equilibrium wage and quantity. You must be able to state why the curve shifted (e.g., "The demand for labor increased due to an increase in the price of the output.") and then connect that shift to the outcome.

• [MCQ Task]: Expect questions that ask you to identify which of several scenarios would cause a specific shift. For example, "Which of the following will cause the supply of auto workers to decrease?" The correct answer would be a determinant of labor supply, such as "Wages for manufacturing jobs in another industry rise significantly."

• [Common Pitfall ①]: Mixing up shifters and movements. A change in the wage rate causes a movement along the labor supply or demand curve. It does not shift the curve. For a curve to shift, the change must be caused by a non-wage determinant, such as productivity, output price, or immigration.

• [Common Pitfall ②]: Confusing product market and factor market effects. An increase in the demand for a product (in the product market) causes an increase in the price of that product. This price increase then causes an increase (a rightward shift) in the demand for the labor that produces it (in the factor market). Do not confuse the initial change in the product market with the resulting change in the factor market.

Key Vocabulary

• Factor Market: A market in which the factors of production (e.g., labor, capital, land) are bought by firms and sold by households.

• Derived Demand: The demand for a resource or factor of production that depends on the demand for the goods and services it is used to produce.

• Labor Demand: The relationship between the wage rate and the quantity of labor that firms are willing and able to hire.

• Labor Supply: The relationship between the wage rate and the quantity of labor that individuals are willing and able to provide.

• Equilibrium Wage: The market-clearing wage rate at which the quantity of labor demanded by firms equals the quantity of labor supplied by workers.