AP® Macroeconomics · Unit 2 · Topic 2.1
The Income Approach and Value Added
GDP can be measured by adding up all income earned or all spending done, because every dollar spent becomes someone's income. Value added at each production stage, summed up, gives the same total as the final sale price.
Every transaction has two sides. When a consumer buys a sweater, that spending is simultaneously income to the seller, who then pays wages, rent, interest, and profit to workers, landlords, lenders, and owners. Add up all spending on final goods and services, or add up all the income generated in producing them, and you land on the same number, because one side's outflow is the other side's inflow. This is why GDP can be calculated either way: the expenditure approach sums spending, the income approach sums wages, rents, interest, and profits.
Value added is the piece of the final price created at each stage of production, equal to a firm's selling price minus what it paid for inputs bought from earlier stages. A wool grower sells wool for 20, a spinner turns it into yarn and sells that for 45, adding 25 in value, and a knitter turns the yarn into a sweater sold for 80, adding 35. The value added at each step, 20 plus 25 plus 35, equals 80, the final sale price, and no more.
This matters because GDP only counts final value, not every transaction along the chain. If you summed the wool sale, the yarn sale, and the sweater sale, you would get 145, triple-counting the wool and double-counting the yarn's contribution. The income and value-added views connect directly: whatever a firm doesn't spend on inputs becomes income to its workers and owners, including profit eventually paid out as dividends, which still counts once, as income to the shareholder who receives it.
Key terms
- Value added
- A stage's selling price minus the cost of inputs it bought from the previous stage of production.
- Income approach
- Measuring GDP by summing all income earned in production: wages, rents, interest, and profits.
- Double-counting
- The error of counting the same value more than once by summing every transaction instead of only value added.
- Final good
- A good sold to its end user rather than used as an input into further production.
- Dividends
- Profit a firm pays out to its shareholders, counted as income once it is received.
Watch it explained
- How it worksHow does value added at each stage of production sum to the final price of a good?
- Worked exampleFind the value added at each stage when wool sells for 20, yarn for 45, and a sweater for 80 dollars.
- Common mistakeWhy isn't GDP the same thing as all the money that changed hands this year?
- Going furtherWhat happens on the income side of the accounts when firms pay out profits as dividends?
Check yourself
End of topic.