GDP Notes: Measuring Output & Income (Expenditure & Income Approaches)

GDP: Measuring Output & Income

• GDP stands for Gross Domestic Product: the market value of all final goods & services produced in an economy over a fixed period.

• Nominal GDP: the current-dollar value of production; quantities valued at current-year prices. In other words, it uses current prices to value outputs.

• Final vs Intermediate goods:

  • Final goods & services: sold to end users and not used to produce another product for resale. Examples: Farmers market goods sold to consumers for final consumption; Frozen food factory goods sold to a factory to produce microwave meals; Microwave meals sold to consumers for final consumption.

  • Intermediate goods: used to build or produce another product that will be sold later.

• The Expenditures Approach to GDP uses expenditures to measure output.

• Important classification: GDP can be measured by expenditures or by income (and should, in theory, yield the same value).

• Key equation (Expenditure approach): $GDP = C + I + G + NX$ where:

  • $C$ = Consumption by households

  • $I$ = Gross Investment (includes Inventories)

  • $G$ = Government Purchases

  • $NX$ = Net Exports (exports − imports)

Final Goods, Intermediate Goods, and the Classification of Expenditures

• Final goods & services definition:

  • Outputs sold to end users and not used to produce another product for subsequent sale.

  • Signals the actual level of consumption and investment in the economy.

• Intermediate goods: Goods used to produce other goods and services; their value is not counted separately in GDP to avoid double counting.

• Expenditure categories (overview):

  • Consumption (C)

  • Gross Investment (I) (includes Inventories)

  • Government Purchases (G)

  • Net Exports (NX)

The Expenditure Approach: Components Defined

• Consumption (C):

  • All expenditures by households on goods and services during a given period.

  • Can be divided into:

  • Consumer Durables

  • Consumer Non-Durables

  • Services

• Consumer Expenditures include items like clothing, food, electronics, and recreation.

• Government Purchases (G):

  • All final goods purchased by federal, state, and local governments.

  • Examples: tanks, police cars, fire engines, office equipment, and services from labor resources (airport security personnel, police, teachers).

• Gross Investment (I):

  • The dollar value of all new capital purchased (as investment) and the expansion of inventories in an economy during a fixed period.

  • Note: This is the economics definition of investment and differs from everyday language usage.

  • Subcategories:

  • Fixed Investment (Business Fixed Investment): Purchases of new capital goods by firms, such as offices, factories, tools, machinery, and buildings (new physical capital).

  • Residential Investment: Purchases of new homes; home improvements (even if you build a new home yourself).

  • Inventory Investment: Changes in inventories from one year to the next. Positive inventory investment when production > sales; negative when sales > production.

• Depreciation (D):

  • The consumption of physical capital; the value of capital that wears out, is used up, or becomes obsolete during a year.

  • Depreciation must be added to income of capital to reflect worn-out capital that must be replaced.

• Net Investment (NI):

  • $NI = GrossInvestment - Depreciation$

  • Positive NI: Capital stock growing (new capital purchases exceed depreciation).

  • Negative NI: Capital stock shrinking (depreciation exceeds new investments).

Net Exports (NX)

• Definition: The difference between exports (goods produced domestically and purchased by foreign consumers) and imports (goods produced in other countries and purchased domestically).

• Net Exports: $NX = X - M$ where X = exports, M = imports.

• Interpretations:

  • Positive NX: Exports exceed imports; the country is producing more than it consumes.

  • Negative NX: Imports exceed exports; the country is consuming more than it produces.

The Expenditure Approach: Summary

• GDP via expenditures: $GDP = C + I + G + NX$

The Income Approach to GDP

• Definition: An approach to measuring GDP by summing incomes earned by factors of production during a period.

• Incomes included:

  • Rent

  • Wages

  • Interest

  • Profits (and losses)

  • Indirect business taxes

  • Depreciation

  • Net foreign factor income

• Net Foreign Factor Income (NFFI):

  • Definition: The difference between income received by residents from factors of production located abroad and income earned by foreigners from factors of production located domestically.

  • Explanation: It captures income earned by U.S. factors abroad minus income earned by foreign factors in the U.S.

• Depreciation (as in the income approach): See above; added to reflect wear and replacement of capital.

• Indirect Business Taxes (IBT):

  • Taxes paid by businesses (property taxes, sales taxes, excise taxes, license fees, tariffs, etc.).

  • These taxes are collected by firms and passed on to consumers as part of prices; they are different from corporate income taxes on profits.

• Calculating GDP using the Income Approach:
  $GDP = Rent + Wages + Interest + Profits/Losses + IndirectBusinessTaxes + Depreciation + NetForeignFactorIncome$

National Income and Related Concepts

• National Income: Total payments to owners of resources plus profits and losses; the sum of rent, wages, interest, and profit & losses earned by firms.

• Net Foreign Factor Income (NFFI): See above; represents the net difference between income from foreign-owned resources abroad and foreign residents’ income earned from domestic resources.

• Depreciation: See above; a cost associated with using up capital; must be added to income measures to reflect the replacement of worn-out capital.

• Indirect Business Taxes: See above; taxes paid by firms that are passed on to consumers in prices.

• Note on calculation methods: The Expenditure Approach sums components of spending; the Income Approach sums payments to factors of production. In theory, both approaches yield the same GDP value.

Quick Reference Formulas

• Expenditure approach: $GDP = C + I + G + NX$

• Net Exports: $NX = X - M$

• Gross Investment: $GrossInvestment = ext{new capital purchases} + ext{inventory investment}$

• Net Investment: $NetInvestment = GrossInvestment - ext{Depreciation}$

• Depreciation:

  • The wear-out of capital; capital replacement cost within a year.

• Income approach: $GDP = Rent + Wages + Interest + Profits/Losses + IndirectBusinessTaxes + Depreciation + NetForeignFactorIncome$