Economic Indicators and the Business Cycle

AP Macroeconomics · College Board Unit 2

What this unit covers

• The circular flow of income, and what GDP is measuring.
• Measuring GDP and its components.
• Real versus nominal GDP, and the GDP deflator.
• Unemployment: measurement and types.
• Inflation, price indices, and who gains and loses from it.
• The business cycle and the output gap.

This unit is 12–17% of the multiple-choice section and it is the most calculation-heavy of the six. Most of its marks are arithmetic with a definition attached, which makes it the unit where careful method pays best.

The circular flow

The circular flow model shows the economy as two flows running in opposite directions between households and firms:

• Households supply factors of production, labour, land, capital, enterprise, to firms through the factor market, and receive income in return: wages, rent, interest and profit.
• Firms supply goods and services to households through the product market, and receive spending in return.

The model produces the identity the whole unit rests on:

Total output = total income = total expenditure

Every dollar of output generates exactly a dollar of income for someone, and is bought with exactly a dollar of spending. This is why GDP can be measured three ways, by adding up output, income or expenditure, and why all three should give the same figure.

Leakages and injections. The simple loop is closed only if nothing leaves it. Saving, taxes and imports are leakages out of the flow; investment, government spending and exports are injections back into it. When injections exceed leakages the flow expands; when leakages exceed injections it contracts. This is the intuition behind the multiplier in Unit 3.

Measuring GDP

GDP is the market value of all final goods and services produced within a country's borders in a given period.

Four words carry the definition, and AP tests each:

• Final: intermediate goods are excluded to avoid double counting. The steel in a car is counted once, in the price of the car.
• Produced: second-hand sales and purely financial transactions (stocks, bonds, transfer payments) are excluded, since nothing new is produced.
• Within borders: output produced domestically by foreign-owned firms counts; output produced abroad by domestic firms does not.
• In a given period: GDP is a flow, not a stock.

The expenditure approach is the version AP uses throughout:

GDP = C + I + G + (X − M)

Two exclusions cause most lost points: transfer payments (pensions, unemployment benefits) are not G because nothing is produced in exchange, and financial investment is not I.

Inventories deserve their own note. Unsold output counts as investment in the year it is produced, not the year it is sold. This is how the accounts keep production and expenditure equal even when firms fail to sell what they make.

GDP versus GNP: GDP counts output within borders; GNP counts output by a country's citizens wherever located. A country with many citizens working abroad can have GNP well above GDP.

What GDP omits: household and unpaid work, the underground economy, leisure, environmental degradation, and the distribution of income. It is a production measure, not a welfare measure, a point worth making explicitly whenever a question asks whether rising GDP means people are better off.

Real versus nominal GDP

This distinction is the single most examined idea in the unit.

• Nominal GDP values output at current-year prices. It rises when output rises or when prices rise, so on its own it tells you nothing about whether the economy grew.
• Real GDP values output at base-year prices, holding prices constant so that only changes in quantity show through. Real GDP is the measure of economic growth.

The two are connected by the GDP deflator:

GDP deflator = (nominal GDP ÷ real GDP) × 100
Real GDP = (nominal GDP ÷ GDP deflator) × 100

In the base year, real GDP equals nominal GDP and the deflator is exactly 100, a useful check on your arithmetic and a common multiple-choice answer.

GDP deflator versus CPI. Both measure the price level, but not of the same things:

So a rise in the price of imported oil raises the CPI directly but does not raise the deflator directly. That difference is a favourite exam question.

Unemployment

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The unemployed are those without work, available for work, and actively seeking work. All three conditions must hold.

Unemployment rate = unemployed ÷ labour force × 100

The labour force = employed + unemployed. It excludes the economically inactive, students, retirees, and discouraged workers who have stopped looking. Dividing by the working-age population instead of the labour force is the classic calculation error.

Labour force participation rate = labour force ÷ working-age population × 100

Types

Natural rate of unemployment = frictional + structural. Cyclical unemployment is zero at full employment.

Full employment does not mean zero unemployment. It means the economy is producing at potential output with only the natural rate remaining. Some frictional unemployment is actually desirable, it means people are searching for the job that best fits them rather than taking the first available.

Why structural unemployment resists demand policy is worth understanding rather than memorising: the problem is a mismatch, not a shortage of jobs. Raising AD creates vacancies the unemployed are not equipped to fill. The remedies are retraining, relocation assistance and education, supply-side measures.

Measurement problems: discouraged workers are counted as inactive, so the measured rate can fall in a downturn as people give up looking; part-time workers who want full-time hours count as fully employed; and the national rate conceals large regional and demographic differences. All three mean the official figure tends to understate the true shortfall of work.

Inflation and price indices

Inflation is a sustained rise in the general price level; deflation is a sustained fall; disinflation is a falling rate of inflation with prices still rising. Disinflation and deflation are not the same thing, and the exam tests the difference.

The CPI tracks a fixed basket of consumer goods:

CPI = (cost of basket in current year ÷ cost in base year) × 100
Inflation rate = (CPI₂ − CPI₁) ÷ CPI₁ × 100

Real versus nominal is the central skill of this unit:

Real value = nominal value ÷ (price index ÷ 100)
Real interest rate ≈ nominal interest rate − inflation rate (the Fisher equation)

Who gains and who loses from unexpected inflation:

• Borrowers gain: they repay in dollars worth less than those borrowed.
• Lenders and savers lose, unless the inflation was anticipated and priced into the nominal rate.
• Fixed-income recipients lose purchasing power, pensioners on a fixed nominal pension are the standard example.
• Holders of real assets: property, commodities, are broadly protected, since asset prices rise with the price level.

The word unexpected matters. If inflation is anticipated, lenders build it into the nominal rate and no transfer occurs. AP tests this distinction directly.

Types: demand-pull (AD rising against capacity limits, "too much money chasing too few goods") and cost-push (input costs rising, shifting SRAS left). The distinction matters because the two call for opposite policy responses, and because only cost-push inflation comes with falling output.

Why inflation is costly, beyond redistribution:

• Menu costs: the real resources used in repricing.
• Shoe-leather costs: the effort spent economising on money holdings when holding cash is expensive.
• Uncertainty: volatile inflation makes long-term contracts and investment planning harder, which discourages investment and slows growth.
• Loss of the store-of-value function: at high rates, money stops doing one of its three jobs.

Deflation is not simply the harmless opposite. Falling prices raise the real value of debt, encourage households to postpone purchases, and can deepen a downturn, which is why central banks target a small positive inflation rate rather than zero.

Measurement problems with CPI: substitution bias (consumers switch away from goods that become expensive, but the basket is fixed), quality changes (a better product at the same price is not really a constant price), and new products entering the basket slowly. All three mean CPI tends to overstate true inflation.

The business cycle

The business cycle is the fluctuation of real GDP around potential output:

• Expansion → peak → contraction/recession → trough → recovery.
• Recessionary gap: actual output below potential; unemployment above the natural rate.
• Inflationary gap: actual output above potential; unemployment below the natural rate, with upward price pressure.

Potential output is what the economy can produce at full employment. It grows steadily over time as capacity grows, while actual output oscillates around it. Drawing the cycle as a wave around a rising trend line is the clearest way to show this, and marks the gap as the vertical distance between the two.

The relationship to unemployment is direct and examinable: unemployment is counter-cyclical, rising in contractions and falling in expansions. Inflation is broadly pro-cyclical, rising as the economy approaches and exceeds potential.

A recession is conventionally identified as a sustained fall in real GDP alongside falls in employment and income, the point being that it is defined on real output, not nominal.

Worked example

An economy has 100 million employed, 8 million unemployed, and 40 million working-age people neither working nor seeking work.

Labour force = 100 + 8 = 108 million
Unemployment rate = 8 ÷ 108 × 100 = 7.4%
Working-age population = 108 + 40 = 148 million
Participation rate = 108 ÷ 148 × 100 = 73%

Note the 40 million are excluded from the unemployment denominator but included in the participation denominator.

Now the real-value step. Nominal wages rise 3% while the CPI rises 5%.

Real wage change ≈ 3% − 5% = −2% → purchasing power falls despite a nominal raise.

If the natural rate here is 5%, then 7.4% measured unemployment implies roughly 2.4 percentage points of cyclical unemployment, a recessionary gap, calling for expansionary policy.

Second worked example: real GDP and the deflator

Nominal GDP is \$22 trillion and the GDP deflator is 110.

Real GDP = (\$22tn ÷ 110) × 100 = \$20 trillion

The following year, nominal GDP rises to \$23.1 trillion and the deflator to 115.5.

Real GDP = (\$23.1tn ÷ 115.5) × 100 = \$20 trillion

Nominal GDP rose 5%, and real GDP did not rise at all. Every dollar of the increase was price, not output. This is exactly why a question about "economic growth" must be answered with real figures, and why quoting nominal growth as growth is a guaranteed lost mark.

Note also that the deflator rose from 110 to 115.5, an inflation rate of (115.5 − 110) ÷ 110 × 100 = 5%, the same 5%, which is the arithmetic reason real GDP was flat.

Common exam mistakes

• Dividing by the working-age population instead of the labour force.
• Counting transfer payments in G, or share purchases in I.
• Including intermediate or second-hand goods in GDP.
• Confusing disinflation with deflation.
• Forgetting that only unexpected inflation redistributes between borrowers and lenders.
• Treating nominal GDP growth as real growth.
• Forgetting that the deflator is 100 in the base year.
• Assuming the CPI and the GDP deflator must move together, imports are in one and not the other.
• Saying full employment means zero unemployment.
• Claiming rising GDP proves rising welfare.

Exam technique

Show every calculation, formula, substitution, result, unit. Method earns credit even when arithmetic slips, and most of this unit's FRQ points are calculation points.

State whether a figure is real or nominal every time. Many questions turn entirely on that distinction, and the word costs nothing to write.

When identifying unemployment type, quote the phrase in the stimulus that settles it, "skills no longer required" is structural, "laid off during the recession" is cyclical, "looking for a better position" is frictional. The stimulus always contains the deciding phrase.

When asked whether something counts in GDP, run the four words of the definition against it in order: final, produced, within borders, this period. One of them always supplies the answer.

Quick revision

• Circular flow: output = income = expenditure. Leakages are saving, taxes, imports; injections are investment, government spending, exports.
• GDP = C + I + G + (X − M); final goods, produced, within borders, this period.
• Transfer payments are not G; buying shares is not I; unsold inventory is.
• Real GDP uses base-year prices; deflator = (nominal ÷ real) × 100, and equals 100 in the base year.
• CPI covers a fixed consumer basket including imports; the deflator covers all domestic output.
• Unemployment rate = unemployed ÷ labour force; participation = labour force ÷ working-age population.
• Natural rate = frictional + structural; cyclical is zero at full employment.
• Real = nominal ÷ (index ÷ 100); real interest ≈ nominal − inflation.
• Unexpected inflation helps borrowers, harms lenders and savers.
• Inflation also costs menu costs, shoe-leather costs and uncertainty.
• Recessionary gap: output below potential. Inflationary gap: above.