Measuring Economic Activity
GDP, GNI, real vs nominal measures, the business cycle, and alternative measures of well-being.
- Explain the three approaches to measuring national income (income, output, expenditure)
- Calculate nominal GDP using the expenditure approach
- Distinguish GDP from GNI and calculate both
- Calculate real GDP/GNI using a price deflator
- Calculate real GDP per capita
- Draw and interpret the business cycle diagram
- Evaluate GDP as a measure of well-being; describe alternative indices
This section is pending teacher review.
National Income: Three Equivalent Approaches
National income can be measured three ways — they should all give the same result (circular flow identity):
Where: C = household consumption, I = investment, G = government spending, X = exports, M = imports.
GDP vs GNI
GNI is more relevant for measuring the income of a country's residents. For most countries GDP ≈ GNI, but they differ significantly for countries with many citizens working abroad (high remittances) or large foreign investment flows.
Nominal vs Real Measures
Nominal GDP is measured at current prices — it can rise simply because prices rise (inflation), even if actual output is unchanged.
Real GDP removes the effect of inflation by expressing output at constant base-year prices — it measures actual changes in output volume.
The price deflator (or GDP deflator) is an index measuring average price levels relative to the base year (base year = 100).
Real GDP per capita
Comparing real GDP per capita at purchasing power parity (PPP) adjusts for differences in price levels between countries, allowing more meaningful international comparisons.
The Business Cycle
The business cycle shows short-term fluctuations in real GDP around the long-term growth trend (potential output):
- Expansion (boom) — actual output above trend; low unemployment, rising prices
- Peak — highest point of the cycle; inflationary pressures may build
- Contraction (recession) — output falls for two or more consecutive quarters; rising unemployment
- Trough — lowest point; spare capacity, high unemployment
- Recovery — output begins rising again
The long-term trend shows growth in potential output (the economy's capacity when resources are fully employed).
Limitations of GDP as a Measure of Well-being
GDP measures the size of the economy, but it has serious limitations as a measure of living standards and well-being:
- Does not account for income distribution — high GDP may coexist with extreme inequality
- Does not capture informal/shadow economy activity
- Ignores environmental degradation — pollution-generating activity raises GDP
- Does not reflect non-market activity (e.g., unpaid household work, volunteering)
- Does not capture leisure time, health, or subjective well-being
Alternative Measures
| Measure | What it captures |
|---|---|
| OECD Better Life Index | Multiple dimensions: housing, income, jobs, community, education, environment, civic engagement, health, life satisfaction, safety, work-life balance |
| Happiness Index (UN World Happiness Report) | Subjective life satisfaction, social support, freedom, generosity, absence of corruption |
| Happy Planet Index | Combines well-being, life expectancy, and ecological footprint — measures sustainable well-being |
- GDP = C + I + G + (X − M) using expenditure approach
- GNI = GDP + net factor income from abroad
- Real GDP removes inflation — use price deflator
- Real GDP per capita = Real GDP ÷ population
- Business cycle: expansion → peak → contraction → trough → recovery
- GDP limitations: ignores distribution, environment, informal sector, non-market activity
- Alternative measures: OECD BLI, Happiness Index, Happy Planet Index
Worked examples are pending teacher review.
Worked Example — Calculating Real GDP
A country has nominal GDP of $500 billion. The price deflator is 125.
Calculate real GDP
Real GDP = ($500bn ÷ 125) × 100 = $400 billion
The economy's real output is $400 billion when measured at base-year prices.
Worked Example — GDP vs GNI
Country A: GDP = $300bn. Citizens working abroad send back $20bn. Foreigners in Country A send back $8bn.
Calculate GNI
GNI = GDP + net factor income = $300bn + $12bn = $312 billion
Practice questions are pending teacher review.