Price Level, Inflation, and Deflation: Key Concepts and Measurement

Price Level, Inflation, and Deflation

Definitions and Importance

The price level is the average level of prices and the value of money in an economy. Understanding changes in the price level is crucial for analyzing economic stability and growth.

• Inflation: A persistently rising price level.

• Deflation: A persistently falling price level.

• Economists study the price level to:

  • Measure the inflation rate or deflation rate.

  • Distinguish between money values and real values of economic variables.

Why Inflation and Deflation Are Problems

Low, steady, and anticipated inflation or deflation is generally not problematic. However, unpredictable inflation or deflation can cause significant economic issues:

• Redistributes income between employers and workers, borrowers and lenders.

• Redistributes wealth.

• Lowers real GDP and employment.

• Diverts resources from production to inflation forecasting.

At its worst, inflation can become hyperinflation, where the inflation rate is so rapid that money loses value extremely quickly (e.g., workers paid twice a day).

Measuring the Price Level: The Consumer Price Index (CPI)

The Consumer Price Index (CPI)

The Consumer Price Index (CPI) measures the average of the prices paid by urban consumers for a "fixed" basket of consumer goods and services. It is the most widely used indicator of inflation.

Reading the CPI Numbers

• The CPI is defined to equal 100 for the reference base period.

• Currently, the reference base period is 1982–1984.

• For example, if the CPI in May 2021 is 269.2, this means the average price level is 169.2% higher than during 1982–1984.

Constructing the CPI

Constructing the CPI involves three main stages:

• Selecting the CPI basket (the set of goods and services regularly purchased by consumers).

• Conducting a monthly price survey (checking prices of the items in the basket).

• Calculating the CPI (using the collected price data).

The CPI Basket

The CPI basket is based on the Consumer Expenditure Survey, which is conducted infrequently. The basket reflects the spending habits of urban consumers and is updated periodically (e.g., using 2019 data).

• Major components include housing, transportation, food and beverages, and other goods/services.

• Housing is typically the largest component.

• Transportation and food/beverages are significant as well.

• All other components account for about 27% of the basket.

The Monthly Price Survey

Every month, Bureau of Labor Statistics (BLS) employees check the prices of approximately 80,000 goods in the CPI basket across 30 metropolitan areas.

Calculating the CPI

• Find the cost of the CPI basket at base-period prices.

• Find the cost of the CPI basket at current-period prices.

• Calculate the CPI for the current period.

Example Calculation

Suppose the CPI basket consists of 10 oranges and 5 haircuts. If the cost in the base period is $50 and the cost in the current period is $70:

• Base-period cost: $50

• Current-period cost: $70

The CPI is calculated using the formula:

$\text{CPI} = \left( \frac{\text{Cost of basket at current-period prices}}{\text{Cost of basket at base-period prices}} \right) \times 100$

For this example:

$\text{CPI} = \left( \frac{70}{50} \right) \times 100 = 140$

This means the CPI is 40 percent higher in the current period than in the base period.

Measuring the Inflation Rate

The major purpose of the CPI is to measure inflation. The inflation rate is the percentage change in the price level from one year to the next.

The inflation formula is:

$\text{Inflation rate} = \left( \frac{\text{CPI this year} - \text{CPI last year}}{\text{CPI last year}} \right) \times 100$

Worked Example: Calculating CPI with Multiple Goods

Suppose an economy produces only eggs and bacon. The following data are observed:

Year	Eggs Quantity	Eggs Price ($)	Bacon Quantity	Bacon Price ($)
2000	100	1.00	50	2.00
2001	110	1.50	45	4.00

To calculate the CPI for 2000 (base year) and 2001:

• Find the cost of the basket (using base-year quantities) at base-year prices and current-year prices.

• Apply the CPI formula for each year.

Additional info: This method ensures that changes in the CPI reflect only price changes, not changes in quantities consumed.

Interpreting CPI and Inflation Rate Graphs

Graphs of the CPI and inflation rate over time help visualize trends, periods of high inflation, and periods of stability. For example, spikes in the inflation rate may correspond to economic shocks or policy changes.

Summary Table: CPI Construction and Interpretation

Step	Description
Select CPI basket	Choose representative goods/services based on consumer spending patterns
Monthly price survey	Collect prices for items in the basket from various locations
Calculate CPI	Compare current prices to base-period prices using the CPI formula
Interpret CPI	Analyze changes to assess inflation or deflation

Key Terms

• Price Level: Average level of prices in the economy.

• Inflation: Persistent increase in the price level.

• Deflation: Persistent decrease in the price level.

• Consumer Price Index (CPI): Measure of average prices paid by consumers for a fixed basket of goods/services.

• Reference Base Period: Time period used as a benchmark for CPI calculations.

• Inflation Rate: Percentage change in CPI from one year to the next.

• Hyperinflation: Extremely rapid inflation causing severe loss of money's value.