Price Elasticity: AP Microeconomics & AP Macroeconomics Study Guide

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AP Microeconomics Connections

Elasticity is a heavily tested topic in AP Microeconomics, appearing in the unit on supply and demand and again in market structures and factor markets. Expect to compute price elasticity of demand using the midpoint formula, classify the result as elastic, inelastic, or unit elastic, and explain what happens to total revenue as a result. You should also be ready to handle income elasticity (which distinguishes normal from inferior goods), cross-price elasticity (which distinguishes substitutes from complements), and price elasticity of supply. A recurring free-response setup gives you a per-unit tax and asks who bears more of the burden — answer using relative elasticities.

AP Macroeconomics Connections

Elasticity appears less explicitly in AP Macroeconomics, but the underlying logic of responsiveness runs through the course. The steepness of the short-run aggregate supply curve determines how much of a demand shock shows up as higher output versus higher prices. The interest sensitivity of investment determines how effective monetary policy is and how large the crowding-out effect of government borrowing will be. In international trade, the responsiveness of import and export volumes to exchange-rate movements governs how a currency depreciation affects the trade balance. Recognizing these as responsiveness questions makes the macro results far easier to reason about.

Calculation and Exam Technique

Use the midpoint method unless a question specifies otherwise: divide each change by the average of the two values rather than by the starting value, so the answer does not depend on the direction of travel. Report elasticity as an absolute value and then classify it. When a question asks about total revenue, state the direction explicitly — increases, decreases, or unchanged — and justify it with the elasticity classification rather than with a bare number. On graphing questions, remember that perfectly inelastic demand is vertical and perfectly elastic demand is horizontal, and label the axes and curves before you shade any tax or surplus area.

Key Terms to Know