macroeconomics

# Macroeconomics

Macroeconomics studies the economy as a whole -- aggregate output, employment, and the price level rather than individual markets or firms. Its central questions are: Why do economies grow? Why do they sometimes contract? What can policy do about it? The field was essentially created by Keynes's response to the Great Depression and has since expanded into a multi-school debate about the roles of government, central banks, and markets in stabilizing economic activity.

**Agent affinity:** keynes (aggregate demand, fiscal policy, liquidity trap), hayek (monetary policy critique, spontaneous order), varian (pedagogical exposition)

**Concept IDs:** econ-gdp-growth, econ-inflation, econ-unemployment, econ-fiscal-policy, econ-banking-system, econ-interest-rates

## The Macroeconomics Toolbox at a Glance

| # | Topic | Core question | Key framework |
|---|---|---|---|
| 1 | GDP and national accounting | How do we measure economic output? | Expenditure, income, and production approaches |
| 2 | Inflation | Why do prices rise and what does it cost? | Quantity theory, Phillips curve, expectations |
| 3 | Unemployment | Why can't everyone who wants work find it? | Natural rate, Okun's law, search and matching |
| 4 | Monetary policy | How do central banks influence the economy? | Taylor rule, liquidity preference, open market operations |
| 5 | Fiscal policy | How do government budgets affect output? | Multiplier, automatic stabilizers, Ricardian equivalence |
| 6 | The business cycle | Why does the economy fluctuate? | AD-AS, IS-LM, real business cycle theory |
| 7 | Growth theory | Why are some countries rich and others poor? | Solow model, endogenous growth, institutions |

## Topic 1 -- GDP and National Accounting

**Gross Domestic Product** is the total market value of all final goods and services produced within a country in a given period. It is the single most important macroeconomic statistic, despite well-known limitations (it excludes household production, leisure, environmental degradation, and inequality).

**Three equivalent approaches.** By expenditure: GDP = C + I + G + (X - M), where C is consumption, I is investment, G is government spending, and (X - M) is net exports. By income: GDP equals total wages + profits + rent + interest + depreciation + indirect taxes. By production: GDP equals the sum of value added across all industries.

**Real vs. nominal.** Nominal GDP uses current prices; real GDP uses constant base-year prices. The GDP deflator is the ratio of nominal to real GDP, providing a broad price index. Comparing real GDP across time reveals changes in actual output rather than price-level changes.

**Limitations.** GDP does not measure welfare. A country can grow GDP by depleting natural resources, increasing pollution, or working its population to exhaustion. Sen's capability approach and alternative measures (HDI, GPI, ISEW) attempt to address these gaps.

**Worked example.** In 2023, US nominal GDP was approximately $27.4 trillion and real GDP (2017 dollars) was approximately $22.4 trillion. The GDP deflator was 27.4/22.4 = 1.223, meaning the overall price level had risen 22.3% since 2017. If nominal GDP grew 6% from 2022 to 2023 but real GDP grew only 2.5%, the remaining 3.5% was inflation, not real output growth. Confusing these leads to the mistake of celebrating nominal growth during inflationary periods.

**GDP per capita and PPP.** Comparing GDP across countries requires adjusting for population (per capita) and price levels (purchasing power parity). India's nominal GDP per capita (~$2,500) understates living standards because goods and services are cheaper in India. At PPP, India's GDP per capita is roughly $9,000 -- still low by global standards but a very different picture from the nominal figure. Always specify whether a comparison uses nominal or PPP figures.

## Topic 2 -- Inflation

**Definition.** Inflation is a sustained increase in the general price level, measured by the CPI (consumer price index) or the GDP deflator. Individual price changes are not inflation -- inflation requires a broad, sustained pattern.

**Causes.** Demand-pull inflation (too much money chasing too few goods -- Friedman's monetarist explanation). Cost-push inflation (rising input costs -- oil shocks, wage spirals). Built-in inflation (expectations become self-fulfilling -- workers expect prices to rise, demand higher wages, firms raise prices to cover costs).

**The quantity theory of money.** MV = PQ, where M is money supply, V is velocity, P is price level, and Q is real output. If V and Q are stable, increasing M raises P proportionally. This is the foundation of monetarism, though Keynesians argue that V is not stable and that the transmission mechanism is more complex.

**The Phillips curve.** Empirically observed inverse relationship between inflation and unemployment (Phillips, 1958). The short-run Phillips curve suggests a trade-off: lower unemployment at the cost of higher inflation. Friedman and Phelps argued this trade-off is temporary -- in the long run, expectations adjust and the curve is vertical at the natural rate of unemployment. The stagflation of the 1970s confirmed this critique.

**Costs of inflation.** Shoeleather costs (more frequent financial transactions), menu costs (frequent repricing), tax distortions (bracket creep, taxation of nominal gains), uncertainty (harder to plan when the unit of account is unstable), redistribution from creditors to debtors.

## Topic 3 -- Unemployment

**Types.** Frictional (between jobs, normal in a dynamic economy), structural (skills mismatch or geographic mismatch between workers and jobs), cyclical (caused by insufficient aggregate demand during recessions).

**The natural rate.** The unemployment rate consistent with stable inflation -- frictional plus structural unemployment. Below the natural rate, labor markets are tight and wages rise faster than productivity, generating inflation. Above the n