Measuring Total Output and Income

Read this chapter, to learn about measuring domestic output, and attempt the "Try It" exercises. The material in this chapter concentrates on the four components of GDP: consumption, investment, government purchases, and net exports. Pay attention to the definition of these components as it may differ from your expectations. For example, note that Investment does not refer to the common knowledge definition of investment as in the trading of stock and bonds. Instead, the Investment component refers mainly to the purchase of physical machinery and equipment needed in the production of goods and services. You will revisit certain sections of the chapter later in this unit.

6.2 Measuring Total Income


  1. Define gross domestic income and explain its relationship to gross domestic product.
  2. Discuss the components of gross domestic income.
  3. Define disposable personal income and explain how to calculate it from GDP.

We saw in the last section that the production of goods and services generates factor incomes to households. The production of a given value of goods and services generates an equal value of total income. Gross domestic income (GDI) equals the total income generated in an economy by the production of final goods and services during a particular period. It is a flow variable. Because an economy's total output equals the total income generated in producing that output, GDP = GDI. We can estimate GDP either by measuring total output or by measuring total income.

Consider a $4 box of Cheerios. It is part of total output and thus is part of GDP. Who gets the $4? Part of the answer to that question can be found by looking at the cereal box. Cheerios are made from oat flour, wheat starch, sugar, salt, and a variety of vitamins and minerals. Therefore, part of the $4 goes to the farmers who grew the oats, the wheat, and the beets or cane from which the sugar was extracted. Workers and machines at General Mills combined the ingredients, crafted all those little O's, toasted them, and put them in a box. The workers were paid part of the $4 as wages. The owners of General Mills and the capital it used received part of the $4 as profit. The box containing the Cheerios was made from a tree, so a lumber company somewhere received part of the $4. The truck driver who brought the box of cereal to the grocery store got part of the $4, as did the owner of the truck itself and the owner of the oil that fueled the truck. The clerk who rang up the sale at the grocery store was paid part of the $4. And so on.

How much of the $4 was income generated in the production of the Cheerios? The answer is simple: all of it. Some of the money went to workers as wages. Some went to owners of the capital and natural resources used to produce it. Profits generated along the way went to the owners of the firms involved. All these items represent costs of producing the Cheerios and also represent income to households.

Part of the $4 cost of the Cheerios, while it makes up a portion of GDI, does not represent ordinary income actually earned by households. That part results from two other production costs: depreciation and taxes related to the production of the Cheerios. Nevertheless, they are treated as a kind of income; we will examine their role in GDI below.

As it is with Cheerios, so it is with everything else. The value of output equals the income generated as the output is produced.