How does an economy move through expansions and recessions, and how do output gaps relate to unemployment and inflation?
Topic 2.7 Business Cycles: describe the phases of the business cycle, relate them to real GDP, unemployment, and inflation, and explain expansionary and recessionary output gaps relative to potential output.
A focused answer to AP Macroeconomics Topic 2.7, covering the phases of the business cycle (expansion, peak, recession, trough), real GDP fluctuations around potential output, recessionary and inflationary gaps, and how unemployment and inflation move over the cycle, with worked analysis.
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What this topic is asking
Topic 2.7 closes Unit 2 by tying the indicators together into the business cycle. The College Board wants you to describe the phases of the cycle, to relate them to real GDP, unemployment, and inflation, and to explain recessionary and inflationary (expansionary) output gaps relative to potential output. This topic is the bridge into the aggregate demand and supply model of the next unit.
The phases of the business cycle
The cycle is not regular or predictable in length, but the pattern of phases recurs. A recession is commonly defined as a significant decline in real GDP lasting more than a few months; a severe, prolonged recession is a depression.
How indicators move over the cycle
The three Unit 2 indicators move together in characteristic ways:
This inverse relationship between output and unemployment is the intuition behind Okun's law (studied informally here): when the economy grows, firms hire and unemployment falls; when it contracts, firms lay off workers and unemployment rises. Inflation tends to rise late in expansions and fall in recessions.
Potential output and output gaps
Comparing actual to potential output defines the two output gaps:
- Recessionary gap: actual real GDP is below potential. Unemployment is above the natural rate (positive cyclical unemployment), and inflationary pressure is weak. The economy operates inside its production possibilities curve.
- Expansionary (inflationary) gap: actual real GDP is above potential. Unemployment is below the natural rate, and inflationary pressure is strong as the economy overheats.
These output gaps are the direct setup for the aggregate demand and supply model in the next unit, where a recessionary gap appears as short-run equilibrium below full-employment output and an inflationary gap appears above it. Fiscal and monetary policy, studied later, are aimed at closing these gaps: expansionary policy to lift a recessionary economy back toward potential, and contractionary policy to cool an overheating one. Connecting Topic 2.7 back through the unit makes the whole picture coherent: real GDP (the output measure), unemployment (the labor-market measure), and inflation (the price measure) all move predictably with the cycle, and potential output is the benchmark that turns "the economy is doing well or badly" into a precise statement about gaps. A strong free-response answer names the phase, states whether real GDP is above or below potential, relates unemployment to the natural rate, and notes the direction of inflationary pressure, all in a few precise sentences. Mastering this vocabulary now means the aggregate demand and supply diagrams of Unit 3 will feel like a natural extension rather than a fresh set of ideas.
Try this
Q1. Name the four phases of the business cycle in order. [2 points]
- Cue. Expansion, peak, recession (contraction), trough.
Q2. Explain what an inflationary (expansionary) gap implies for unemployment relative to the natural rate. [2 points]
- Cue. Actual real GDP is above potential, so unemployment is below the natural rate; the economy is overheating and inflationary pressure is strong.
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 2020 (style)1 marksMultiple choice. During the recession phase of the business cycle, we would most likely observe (A) rising real GDP and falling unemployment. (B) falling real GDP and rising cyclical unemployment. (C) rising real GDP and rising inflation. (D) constant real GDP and zero unemployment. (E) falling unemployment and falling real GDP.Show worked answer →
The answer is (B). A recession is a period of falling real GDP, during which firms cut output and lay off workers, so cyclical unemployment rises and inflationary pressure typically eases.
(A) and (C) describe an expansion. (D) describes neither phase realistically; zero unemployment never occurs. (E) is internally inconsistent: falling real GDP raises, not lowers, unemployment.
AP 2022 (style)4 marksFree response. An economy is producing below its potential output. (a) Identify whether this is a recessionary or an inflationary gap. (b) Describe what is happening to cyclical unemployment relative to the natural rate. (c) Using the business cycle, identify the phase the economy is in. (d) Explain what happens to real GDP, unemployment, and inflationary pressure as the economy moves from a trough into an expansion.Show worked answer →
A 4-point conceptual FRQ.
(a) Gap (1 point): producing below potential output is a recessionary gap.
(b) Cyclical unemployment (1 point): the actual unemployment rate is above the natural rate, so there is positive cyclical unemployment.
(c) Phase (1 point): the economy is in a recession (or contraction), the phase of falling or below-potential output.
(d) Trough into expansion (1 point): as the economy moves from a trough into an expansion, real GDP rises, unemployment falls (cyclical unemployment shrinks toward zero), and inflationary pressure tends to build as output approaches potential.
Markers reward identifying the recessionary gap, positive cyclical unemployment, the recession phase, and the correct directions for real GDP, unemployment, and inflation during recovery.
Related dot points
- Topic 2.1 The Circular Flow and GDP: describe the circular flow of income and expenditure, define gross domestic product, and explain the expenditure approach using C plus I plus G plus net exports.
A focused answer to AP Macroeconomics Topic 2.1, covering the circular flow of income and expenditure, the definition of GDP, the expenditure and income approaches, what is and is not counted, and the expenditure formula, with full worked calculations.
- Topic 2.2 Limitations of GDP: explain why GDP omits non-market and underground activity, ignores distribution, leisure, and externalities, and why GDP per capita is used to compare living standards.
A focused answer to AP Macroeconomics Topic 2.2, covering what GDP omits (non-market production, the underground economy, distribution, leisure, externalities and quality), why GDP per capita is used to compare living standards, and the difference between GDP and well-being, with worked questions.
- Topic 2.3 Unemployment: define the labor force and unemployment rate, calculate them, distinguish frictional, structural, and cyclical unemployment, and explain the natural rate and full employment.
A focused answer to AP Macroeconomics Topic 2.3, covering the labor force, the unemployment rate and labor force participation rate, frictional, structural and cyclical unemployment, the natural rate of unemployment, full employment, and limitations of the measure, with full worked calculations.
- Topic 2.4 Price Indices and Inflation: define inflation and deflation, build and use the Consumer Price Index, calculate the inflation rate, and distinguish demand-pull from cost-push inflation.
A focused answer to AP Macroeconomics Topic 2.4, covering inflation and deflation, the Consumer Price Index and the market basket, calculating the CPI and the inflation rate, demand-pull versus cost-push inflation, and biases in the CPI, with full worked calculations.
- Topic 2.6 Real versus Nominal GDP: distinguish nominal from real GDP, use the GDP deflator to convert between them, and explain why real GDP is the correct measure of output growth.
A focused answer to AP Macroeconomics Topic 2.6, covering nominal versus real GDP, the GDP deflator, converting between nominal and real GDP, why real GDP measures true growth, and calculating real GDP growth rates, with full worked calculations.
Sources & how we know this
- AP Macroeconomics Course and Exam Description — College Board (2023)