GDP and the CPI: Tracking the Macroeconomy

The National Income and Product Accounts

  • The national income and product accounts, often referred to as the national accounts, are a specific set of numbers used by countries to monitor the flow of money between different sectors of the economy.

  • Household Income and Flow:

    • Households obtain income through factor markets in the form of wages, interest earned on bonds, dividends from stocks, and rent from land.

    • A stock represents a share of ownership in a company held by a shareholder.

    • A bond is a form of borrowing characterized as an IOU that pays a specific rate of interest.

    • Households also receive government transfers, which are payments made by the government to individuals without an exchange of goods or services.

    • Disposable income is the total income available to households after taxes are subtracted. It can be used for either consumption or saving.

  • Savings and Investment:

    • Private savings is defined as the portion of disposable income not spent on consumption. It is calculated as: Private Savings=Disposable Income−Consumer Spending\text{Private Savings} = \text{Disposable Income} - \text{Consumer Spending}.

    • Financial markets consist of the banking, stock, and bond markets. These markets channel private savings and foreign lending into investment spending, government borrowing, and foreign borrowing.

    • Investment spending refers to spending on productive physical capital (like machinery and structures) and changes to inventories (stocks of goods/raw materials held for business operations).

  • Government and Foreign Sectors:

    • Government purchases (G) of goods and services are funded by tax receipts and government borrowing.

    • Exports (X) create an inflow of funds from the rest of the world.

    • Imports (IM) result in an outflow of funds to the rest of the world.

Gross Domestic Product (GDP)

  • Gross Domestic Product (GDP) measures the total value of all final goods and services produced within an economy during a specific year. It specifically excludes the value of intermediate goods to avoid double counting.

  • Final goods and services are those sold to the end user.

  • Intermediate goods and services are inputs purchased by one firm from another for use in the production of final goods.

  • Aggregate spending is the sum of consumer spending (CC), investment spending (II), government purchases (GG), and net exports (X−IMX - IM).

  • Calculation Methods:

    • Value Added Approach: Summing the value added by every producer. Value added is defined as the value of a producer's sales minus the cost of intermediate goods.

    • Expenditure Approach: Summing all spending on domestic final goods and services. The formula is: GDP=C+I+G+X−IMGDP = C + I + G + X - IM.

    • Income Approach: Summing all income paid to factors of production (wages, interest, rent, and profit).

  • Numerical Example of GDP Components:

    • Based on a hypothetical steel/auto economy:

    • American Ore, Inc.: Value of sales = $4,200\$4,200; Intermediate goods = $0\$0; Value added = $4,200\$4,200.

    • American Steel, Inc.: Value of sales = $9,000\$9,000; Intermediate goods = $4,200\$4,200; Value added = $4,800\$4,800.

    • American Motors, Inc.: Value of sales = $21,500\$21,500; Intermediate goods = $9,000\$9,000; Value added = $12,500\$12,500.

    • Total GDP: $21,500\$21,500 (Sum of value added or final sale price).

  • Inclusions vs. Exclusions:

    • Included: Domestically produced final goods/services, capital goods, new construction, and inventory changes.

    • Excluded: Intermediate goods, inputs, used goods, financial assets (stocks/bonds), and foreign-produced goods.

    • Note on Housing: GDP includes an imputation for the value of "owner-occupied housing." If a person buys the home they previously rented, GDP does not drop; statisticians estimate the rental value the owner "pays" themselves.

Gross National Product (GNP) and Global Comparisons

  • Gross National Product (GNP): The total factor income earned by the residents of a country. It includes income earned abroad by residents and excludes income earned domestically by foreigners.

  • Usage: GDP is generally preferred for tracking short-run production because data on international factor income flows can be unreliable.

  • Discrepancies:

    • In the U.S. (2010), GNP was roughly 1.3%1.3\% larger than GDP.

    • In Ireland (2010), GNP was only 82%82\% of GDP, primarily because foreign corporations (mostly U.S.) own significant industry there, and profits flow out of the country.

Real versus Nominal GDP

  • Nominal GDP: The value of final goods and services at the prices current in the year they are produced.

  • Real GDP: The total value of final goods and services calculated using prices from a selected base year. This removes the effect of price changes to measure actual production growth.

  • Example Comparison (Year 1 vs. Year 2):

    • If Apple prices rise from $0.25\$0.25 to $0.30\$0.30 and Orange prices rise from $0.50\$0.50 to $0.70\$0.70, nominal GDP might rise significantly while real GDP (using Year 1 prices) shows lower, more accurate growth in output.

  • GDP per capita: A measure of average GDP per person. Derived by dividing GDP by the population size.

  • Chained Dollars: The method used in the U.S. to calculate real GDP by averaging growth rates from both an early and late base year.

Price Indexes and Inflation

  • Aggregate Price Level: A measure of the overall level of prices in the economy.

  • Market Basket: A representative collection of goods and services purchased by a typical consumer.

  • Price Index Calculation:

    • Price Index=Cost of market basket in given yearCost of market basket in base year×100\text{Price Index} = \frac{\text{Cost of market basket in given year}}{\text{Cost of market basket in base year}} \times 100

  • Inflation Rate: The annual percentage change in a price index.

    • Inflation Rate=Price Index in year 2−Price Index in year 1Price Index in year 1×100\text{Inflation Rate} = \frac{\text{Price Index in year 2} - \text{Price Index in year 1}}{\text{Price Index in year 1}} \times 100

  • Major Price Indexes:

    • Consumer Price Index (CPI): Measures the cost of a market basket for a typical urban American family. Components include Housing (41%41\%), Food/Beverages (15%15\%), Transportation (12%12\%), etc.

    • Producer Price Index (PPI): Measures the cost of a basket of goods purchased by firms. It is often a leading indicator of CPI changes.

    • GDP Deflator: A price measure calculated as: 100×Nominal GDPReal GDP100 \times \frac{\text{Nominal GDP}}{\text{Real GDP}}.

Practical Applications and Limitations

  • CPI Bias: Many economists believe the CPI overstates inflation because it does not account for consumers substituting cheaper goods for expensive ones or for the increased value of money due to innovation.

  • Indexing: Many government payments, such as Social Security, are indexed to the CPI. When the CPI rises, payments are adjusted upward automatically to preserve purchasing power.

  • Historical Context: National accounts were created following the Great Depression. Simon Kuznets developed the first versions, presented to Congress in 1937. The push to finalize these metrics occurred during WWII for wartime planning.