GDP and the Business Cycle: AP Macroeconomics Study Guide

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Where GDP Sits in the AP Macro Course

Gross domestic product is introduced in the AP Macroeconomics unit on economic indicators and the business cycle, where it sits alongside unemployment and inflation as one of the three headline measures of macroeconomic performance. You are expected to compute GDP by the expenditure approach, distinguish real from nominal output, calculate and interpret the GDP deflator, and locate an economy on the business cycle diagram. GDP then becomes the vertical measurement in nearly everything that follows: the aggregate demand and aggregate supply model uses real output on the horizontal axis, output gaps are defined relative to full-employment real GDP, and the long-run growth unit is about shifting potential output outward.

The Calculations You Will Be Asked to Do

Know the expenditure identity cold: GDP = C + I + G + (X - M). Be ready to compute nominal GDP from a table of prices and quantities, then compute real GDP for the same year using base-year prices. The GDP deflator is nominal divided by real, times 100, and the inflation rate implied by it is the percentage change in the deflator between two years. Real GDP per capita is real GDP divided by population. You should also be comfortable converting between growth rates: nominal growth minus the deflator's inflation rate approximates real growth. Show the setup, not just the answer — free-response points are awarded for correct work as well as correct numbers.

What Is Excluded, and Other Classic Traps

GDP counts only final goods and services produced currently within a country's borders. That excludes intermediate goods (to avoid double counting), used goods and secondhand sales, purely financial transactions such as buying stocks or bonds, transfer payments such as Social Security and unemployment benefits, unpaid household production, and illegal or unreported activity. Imports are subtracted, so a rise in imports with everything else constant reduces measured GDP. Two more traps recur: a recession on the AP exam is a decline in real GDP and rising unemployment, and it appears as a movement from a peak toward a trough on the business cycle diagram — not as an inward shift of the production possibilities curve, because capacity has not been destroyed. And remember GDP measures production, not welfare or income distribution.

Key Terms to Know

These are the terms that show up in multiple-choice stems and in the wording of free-response prompts, so knowing the precise definition of each — not just a rough sense of it — is worth real points. Pay particular attention to the pairs that are easy to conflate under time pressure: nominal against real, GDP against GNP, and recessionary against inflationary gap.