## 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.

### 6.1 Measuring Total Output

Take the example given in Table 6.1 "Final Value and Value Added", which is a simplified illustration of a house built in three stages. If there were a sales tax of 10% on the house, the household buying it would pay $137,500, of which the construction firm would keep$125,000 of the total and turn $12,500 over to the government. With a 10% VAT, the sawmill would pay the logger$13,200, of which the logger would keep $12,000 and turn$1,200 over to the government. The sawmill would sell the lumber to the construction firm for $27,500 - keeping$26,200, which is the $25,000 for the lumber itself and$1,200 it already paid in tax. The government at this stage would get $1,300, the difference between the$2,500 the construction firm collected as tax and the $1,200 the sawmill already paid in tax to the logger at the previous stage. The household would pay the construction firm$137,500. Of that total, the construction firm would turn over to the government $10,000, which is the difference between the$12,500 it collected for the government in tax from the household and the $2,500 in tax that it already paid when it bought the lumber from the sawmill. The table below shows that in the end, the tax revenue generated by a 10% VAT is the same as that generated by a 10% tax on final sales. Why bother to tax in stages instead of just on final sales? One reason is simply record keeping, since it may be difficult to determine in practice if any particular sale is the final one. In the example, the construction firm does not need to know if it is selling the house to a household or to some intermediary business. Also, the VAT may lead to higher revenue collected. For example, even if somehow the household buying the house avoided paying the tax, the government would still have collected some tax revenue at earlier stages of production. With a tax on retail sales, it would have collected nothing. The VAT has another advantage from the point of view of government agencies. It has the appearance at each stage of taking a smaller share. The individual amounts collected are not as obvious to taxpayers as a sales tax might be. Good Price Value Added Tax Collected − Tax Already Paid = Value Added Tax Logs$12,000 $12,000$1,200 − $0 =$1,200
Lumber $25,000$13,000 $2,500 −$1,200 = $1,300 House$125,000 $100,000$12,500 − $2,500 =$10,000
Total     $16,200 −$3,700 = \$12,500