Unit 2 · Topic 2.1

The Circular Flow and GDP

The circular flow shows households selling factors of production to firms and buying their output, so spending on final goods equals income.

Practice 1: Principles and ModelsPractice 2: Interpretation

Part 1 · Hook

Why this matters

A bakery sells a $300 batch of bread. The flour in it cost $120 and the wheat in the flour cost $50. How much did the economy produce: $300 or $470? A country adds up millions of sales like these to get one number for its output, and getting it right means knowing what to count, what to leave out, and why one person's spending is always another person's income.

Part 2 · Before you start

What this builds on

Part 3 · Prerequisite check

Quick check before you start

1. Which of these is a factor of production?

  1. Labor
  2. Money in a savings account
  3. A share of stock
  4. A finished bicycle
Show the answer

The factors of production are land, labor, capital and entrepreneurship. Households own them and sell their services to firms.

  • Correct: Labor:
  • Money in a savings account:
  • A share of stock:
  • A finished bicycle:

2. In a market, the price buyers pay times the quantity sold is

  1. the total spending on that good
  2. the shortage at that price
  3. the opportunity cost of the good
  4. the quantity demanded
Show the answer

Price times quantity is total spending, which is also the sellers' revenue. GDP adds this up for final goods and services.

  • Correct: the total spending on that good:
  • the shortage at that price:
  • the opportunity cost of the good:
  • the quantity demanded:

Part 4 · See it

See it first

Circular flow diagram. In the product market, households spend money on goods and services and firms receive it as revenue. In the factor market, households supply land, labor, capital and entrepreneurship and receive wages, rent, interest and profit as income. Money moves around the outer loop, real goods and factors around the inner loop the other way.
Households sell factors to firms and buy their output; every dollar of spending on output returns to households as income. LevlPrep original diagram.

Part 5 · Step by step

How it works, step by step

  1. Households spend on goods and services in the product marketfirms receive that spending as revenue
  2. Firms receive revenuethey pay wages, rent, interest and profit to households in the factor market
  3. Households receive factor incomethey spend it again, so total spending on final output equals total income
  4. GDP adds up spending on final goods onlyintermediate goods, used goods, financial trades and transfer payments are left out

Part 6 · Key ideas

Key ideas

  • GDP is the market value of all final goods and services produced within a country in a year.
  • The expenditure approach: GDPGDP=C+I+G+(X−M)= C + I + G + (X - M). Imports are subtracted because they are already inside C, I and G but were made abroad.
  • In GDP, investment means new capital, new homes and added inventory, not buying stocks.
  • Left out: intermediate goods (double counting), used goods, stocks and bonds, and transfer payments. Counting each stage's value added gives the same total as counting final goods.

Part 7 · Misconception

A common mistake

The wrong idea: Adding up every sale in the economy, including the flour and the wheat, gives GDP.

What actually happens: Only final goods count. The bread's price already includes the flour and wheat, so adding them counts the same production two or three times.

Part 8 · Check yourself

Check yourself

Exam-style questions. Anything you miss goes into your review queue.

Data

Spending in Country X for one year

Country X, one year (billions of dollars; invented data for practice)
CategoryAmount
Consumption spending by households600
Investment spending by firms150
Government purchases of goods and services200
Exports80
Imports100
Transfer payments (pensions and other benefit checks)90

1. Use the table. What is GDP in Country X, in billions of dollars?

Type a number. A four-function calculator is allowed, as on the exam.

Show the answer

Use the expenditure approach and leave out transfer payments: 600+150+200+(80−100)600 + 150 + 200 + (80 - 100)=930= 930 billion dollars.

  • Answer: 930

2. Use the table. What are net exports in Country X, in billions of dollars?

Type a number. A four-function calculator is allowed, as on the exam.

Show the answer

Net exports are exports minus imports: 80−100=−2080 - 100 = -20 billion dollars. More was bought from abroad than sold abroad.

  • Answer: -20

Scenario

From wheat to a loaf of bread

In Country X a farmer grows wheat and sells it to a mill for $50. The mill grinds it into flour and sells the flour to a bakery for $120. The bakery bakes bread and sells all of it to shoppers for $300. Nothing else is produced along this chain this year.

3. How much does this chain add to Country X's GDP, in dollars?

Type a number. A four-function calculator is allowed, as on the exam.

Show the answer

Count only the final good, the bread sold to shoppers: $300. The wheat and the flour are intermediate goods; their value is already inside the price of the bread.

  • Answer: 300

4. Which of these are counted in this year's GDP of the United States? Select all that apply.

  1. A pension check mailed to a retiree
  2. A house built and sold this year
  3. A haircut bought at a local salon
  4. A car built in Ohio by a company based in Japan
  5. A ten-year-old car bought from a neighbor
  6. Shares of stock bought through an app
Show the answer

GDP is the market value of final goods and services produced within a country in a year. New production counts; used goods, financial trades and transfers do not.

  • A pension check mailed to a retiree: A transfer payment: nothing is produced in exchange, so it is left out.
  • Correct: A house built and sold this year: Right: a newly built home is counted, as residential investment.
  • Correct: A haircut bought at a local salon: Right: a service produced this year and sold at market value.
  • Correct: A car built in Ohio by a company based in Japan: Right: GDP counts what is produced inside the country's borders, whoever owns the factory.
  • A ten-year-old car bought from a neighbor: A used good was counted in the year it was made; reselling it produces nothing new.
  • Shares of stock bought through an app: A stock purchase is a financial exchange of ownership, not production of a good or service.

5. A bakery buys a new delivery truck made this year in the same country. In which part of GDP is the truck counted?

  1. It is an intermediate good and is not counted
  2. Investment
  3. Consumption
  4. Government purchases
Show the answer

Investment in GDP means spending on new capital (machines, tools, buildings), new homes and changes in inventories. Capital goods are final goods, not intermediate ones.

  • It is an intermediate good and is not counted: The truck is not used up in making one loaf; it is a capital good used for years, so it is a final good counted as investment.
  • Correct: Investment: Right: new capital goods bought by firms are investment spending.
  • Consumption: Consumption is spending by households on goods and services for their own use, not a firm's capital.
  • Government purchases: The bakery is a private firm, not the government.

Part 9 · Summary

Summary

The circular flow shows households selling factors of production to firms and buying their output, so spending on final goods equals income. GDP is the market value of final goods and services produced within a country in a year, measured by C+I+G+(X−M)C + I + G + (X - M). Intermediate goods, used goods, financial trades and transfer payments are left out.

Part 10 · Up next

What comes next

Part 11 · Connections

Connections

Question set for this topic