What shifts the demand for and supply of a factor like labor, and how does that change the equilibrium wage and employment?
Topic 5.2 Changes in Factor Demand and Factor Supply: identify the determinants that shift factor demand and factor supply, and predict the effect on the equilibrium factor price and quantity.
A focused answer to AP Microeconomics Topic 5.2, covering the determinants that shift factor (labor) demand and supply, including product demand, productivity, prices of other factors, and the number of workers, and how shifts change the equilibrium wage and employment, with worked exam-style questions.
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What this topic is asking
Topic 5.2 applies the shift-versus-movement discipline of Unit 2 to factor markets. The College Board wants you to identify the determinants that shift factor demand and factor supply (using labor as the example), and predict the effect on the equilibrium factor price (wage) and quantity (employment), including the indeterminate double-shift cases.
The factor market and its curves
A competitive factor market looks like a product market with relabelled axes: the wage (factor price) is on the vertical axis and the quantity of labor (employment) on the horizontal. Factor demand is the downward-sloping marginal revenue product curve (Topic 5.1); factor supply slopes upward, because a higher wage draws more workers into the market. Their intersection sets the equilibrium wage and employment.
Determinants that shift factor demand
The derived-demand link is the one examiners test most: anything that raises the value of the output, higher product demand or a higher product price, raises the marginal revenue product and shifts factor demand right. A productivity gain does the same by raising marginal product. The price of a related factor matters because firms can sometimes substitute capital for labor (a cheaper substitute factor reduces demand for labor) or because factors are used together (a complement).
Determinants that shift factor supply
More available workers shift labor supply right, lowering the equilibrium wage; better outside options shift it left, raising the wage. These are the supply-side mirror of the product-market determinants.
Predicting the equilibrium
The four single-shift outcomes mirror Topic 2.7 exactly, with "wage" for price and "employment" for quantity:
- Labor demand increases: wage up, employment up. Demand decreases: wage down, employment down.
- Labor supply increases: wage down, employment up. Supply decreases: wage up, employment down.
For a double shift, one of wage and employment is determinate (both shifts push it the same way) and the other indeterminate, just as in product markets.
Try this
Q1. The demand for a product rises. State the effect on the demand for the labor that makes it and why. [2 points]
- Cue. Labor demand increases (shifts right), because labor demand is derived: higher product demand raises the marginal revenue product of labor.
Q2. Labor supply decreases while labor demand is unchanged. State the effect on the equilibrium wage and employment. [2 points]
- Cue. The wage rises and employment falls (a single leftward supply shift).
Exam-style practice questions
Practice questions written in the style of College Board exam questions on this dot point, with worked answer explainers. The year tag is the paper they imitate, not the source.
AP 2018 (style)1 marksMultiple choice. An increase in the demand for a product will, in the related labor market, (A) shift labor supply right. (B) shift labor demand right, raising the wage and employment. (C) shift labor demand left. (D) leave labor demand unchanged. (E) shift labor supply left.Show worked answer →
The answer is (B). Labor demand is derived from product demand, so when demand for the product rises, the marginal revenue product of labor rises, shifting labor demand right and increasing both the equilibrium wage and employment.
(A) and (E) affect supply, not demand. (C) is the wrong direction. (D) ignores derived demand.
AP 2021 (style)4 marksFree response. In a competitive labor market, the government raises immigration, increasing the number of available workers, while at the same time the demand for the industry's product falls. (a) State the effect on labor supply and explain. (b) State the effect on labor demand and explain. (c) Determine the effect on the equilibrium wage. (d) Explain why the effect on equilibrium employment is indeterminate.Show worked answer →
A four-point double-shift labor FRQ.
(a) (1 point): labor supply increases (shifts right) because there are more workers available.
(b) (1 point): labor demand decreases (shifts left) because lower product demand lowers the marginal revenue product of labor (derived demand).
(c) (1 point): the equilibrium wage definitely falls, because both a rightward supply shift and a leftward demand shift push the wage down.
(d) (1 point): equilibrium employment is indeterminate because the supply increase pushes employment up while the demand decrease pushes it down; the net effect depends on the relative sizes of the shifts.
Related dot points
- Topic 5.1 Introduction to Factor Markets: explain that factor demand is derived demand, define and calculate marginal revenue product, and state the hiring rule that marginal revenue product equals marginal factor (resource) cost.
A focused answer to AP Microeconomics Topic 5.1, covering derived demand, marginal product and marginal revenue product, marginal factor (resource) cost, and the profit-maximizing hiring rule that marginal revenue product equals marginal factor cost, with worked exam-style questions.
- Topic 5.3 Profit-Maximizing Behavior in Perfectly Competitive Factor Markets: apply the marginal revenue product equals wage rule for a wage-taking firm, and use the least-cost and profit-maximizing input combination rules across multiple factors.
A focused answer to AP Microeconomics Topic 5.3, covering the hiring rule for a firm in a competitive factor market, the least-cost combination of inputs rule, the profit-maximizing input rule, and how a firm chooses between labor and capital, with worked exam-style questions.
- Topic 5.4 Monopsonistic Markets: explain why a monopsonist's marginal factor cost lies above the labor supply curve, find the monopsony wage and employment, and compare them with the competitive outcome.
A focused answer to AP Microeconomics Topic 5.4, covering monopsony as a single buyer of a factor, why marginal factor cost lies above the supply curve, how the monopsonist sets employment where marginal revenue product equals marginal factor cost and the wage off the supply curve, and the resulting lower wage and employment, with worked exam-style questions.
- Topic 2.7 Market Disequilibrium and Changes in Equilibrium: explain how shortages and surpluses arise and self-correct, predict the new equilibrium after a single shift, and handle the indeterminate cases of a double shift.
A focused answer to AP Microeconomics Topic 2.7, covering shortages and surpluses, how price adjusts to clear a market, the four single-shift outcomes, and the indeterminate results of a double shift, with worked exam-style questions.
- Topic 3.1 The Production Function: define total, marginal, and average product, explain the law of diminishing marginal returns, and relate the product curves to one another.
A focused answer to AP Microeconomics Topic 3.1, covering the production function, total product, marginal product and average product, the law of diminishing marginal returns, and how the product curves relate to one another, with worked exam-style questions.
Sources & how we know this
- AP Microeconomics Course and Exam Description — College Board (2023)