Chapter 5 — GDP, Income, Wealth, and Welfare

Core question

What does GDP measure, and what additional evidence is needed before saying that a country is wealthier or better off?

Learning outcomes

You will be able to:

• apply GDP's production boundary without double counting;
• reconcile production, income, and expenditure approaches;
• calculate nominal GDP, real GDP, and a GDP deflator;
• distinguish output, income, wealth, and welfare.

1. GDP is a flow of production

Gross domestic product is the market value of final goods and services produced within an economy during a stated period.

GDP is not “national wealth.” Wealth is a stock of assets minus liabilities. GDP is a flow of newly produced value.

2. Avoid double counting with final output or value added

Counting every sale gives £9, which double-counts inputs. Count the £5 final bread or sum value added: 1 + 2 + 2 = £5.

An input sold to a firm is intermediate; the same item sold for final use may be final. Classification depends on use, not physical appearance.

3. Three views of the same activity

Production creates output, income, and expenditure at the same time.

Imports are subtracted because they may already appear in C, I, or G but were produced abroad.

Transaction check

4. Nominal and real GDP

Suppose the economy produces coffee and books:

Year 1 nominal GDP:

Year 2 nominal GDP:

Year 2 GDP at Year 1 prices:

Real output growth is 960/900 - 1 = 6.7%, not the 24.7% rise in nominal GDP.

The fixed-base GDP deflator is:

In practice, statistical agencies use chain-weighting and richer price/quality methods. The classroom calculation teaches the separation of quantities from prices.

5. GDP per person is an average

It is a useful indicator of average productive capacity. It does not report:

• income or wealth distribution;
• unpaid care and household production;
• leisure, health, security, or political freedom;
• environmental depletion and ecosystem damage;
• quality improvements that are difficult to price;
• who receives gains from digital services with zero money price.

Use a dashboard: real income per person, median income, distribution, health, education, leisure, environmental stocks, and subjective well-being where appropriate.

6. Stocks and flows

Investment adds to capital; depreciation removes from it:

A country can raise current GDP while running down natural or produced assets. Output and balance-sheet sustainability are distinct.

7. National accounts are a statistical system

The UN describes the System of National Accounts as the internationally agreed framework linking production, income, consumption, saving, investment, and transactions with the rest of the world. The 2025 SNA is the current edition listed by the UN Statistics Division (UNSD, 2025).

This matters because GDP is not a raw observation. It is a constructed estimate using definitions, surveys, administrative records, imputations, seasonal adjustment, and revisions.

Before comparing GDP figures, check:

nominal or real? total or per person? level or growth?
annualised or not? seasonally adjusted? first release or revised?
same production boundary and price method?

Practice

An economy reports nominal GDP growth of 7%, inflation of 4%, and population growth of 1%.

1. Approximate real GDP growth.
2. Approximate real GDP-per-person growth.
3. Explain why neither answer establishes that the median household is better off.
4. Classify a new house, an old house, a broker's fee, a share purchase, and unpaid childcare.
5. Name one wealth and one welfare indicator to add.

Quick check

• GDP is current domestic production, not wealth.
• Final expenditure and value added avoid double counting.
• C + I + G + NX is an accounting identity, not a causal model.
• Real GDP removes price change; per-person GDP also adjusts for population.
• Welfare requires a wider dashboard.

Next: measure price change, purchasing power, and labour-market utilisation.