Consumer Price Index (CPI)

What is CPI?

The Consumer Price Index, or CPI, is the measure of the monthly change in prices that consumers are paying for goods and services. Some of the goods and services measured in the CPI include, food, housing, transportation, and healthcare, among others. The CPI is used as an indicator of inflation or deflation in the economy.

How is CPI calculated?

The CPI is calculated by first choosing the “market basket”, which is a sample of goods and services that can best reflect what urban consumers are spending their money on. The specific items in this “basket” are determined through surveys and data analysis. Each item in the market basket is assigned a weight based on the importance it plays in a consumer’s overall budget. Once the goods and services that will be measured are determined and a weight is assigned, the prices of these items are gathered from a wide range of sources. The prices are then multiplied by their assigned weight, averaged, and then divided into a percentage increase or decrease from the base period.

Is CPI the same as inflation?

While CPI is not the same thing as inflation, it is used as a determining factor in inflation. The CPI can be viewed as a number used to measure change, specifically the change in the prices paid by consumers for a “basket” of goods and services. Over time, we can use the monthly CPI published by the Bureau of Labor Statistics to determine the difference between two points in time, which would then be used to calculate inflation.

What does a high CPI mean?

A high CPI indicates a period of higher inflation of an economy. A higher CPI and higher inflation rate mean that the same products cost consumers more money to buy the same products now than it did in the past. Higher CPI also means that consumers’ dollars have less purchasing power, and workers’ wages have less value. High CPIs impact the overall economy, along with investment decisions, interest rates, and public policy regarding interest rate adjustments.

What are the limitations of using CPI as a measure of inflation?

Overall, CPI is a great indicator of inflation in an economy, but there are some limitations. For one, CPI doesn’t factor in the effects of substitution, assuming that when the price of a good increases, consumers will continue to buy the same amount at its increased price without considering substitute goods. CPI also doesn’t consider improvements in product quality as a product of innovation. Products are not even included in the CPI’s basket of goods until they are considered “staple consumer purchases.” This means new products that can generate considerable consumer expenditure can still be left out of the CPI calculation. Another common criticism of CPI is that it doesn’t account for demographic groups and subsequent regional price movements.

How often is the CPI updated?

The CPI in the United States is updated on a monthly basis, which is often enough to continuously give up-to-date assessments on inflation. If there is an event in which new data is available sooner than the scheduled monthly update, the CPI may be revised outside of the specific frequency. Other countries may update their CPI quarterly or even annually.