This article is about the Consumer Price Index. For the article on the company with ticker CPI or companies named CPI, see CPI (disambiguation).
The Consumer Price Index (CPI, or headline inflation) provides data on the month-over-month and year-over-year changes in the prices paid by urban consumers for a representative basket of goods and services. It is the main inflation report for the futures and financial markets. Unexpected rises in this indicator usually lead to falling bond prices, rising interest rates, and increased market volatility.
The U.S. Bureau of Labor Statistics (BLS) measures two kinds of CPI statistics: CPI for urban wage earners and clerical workers (CPI-W), and the chained CPI for all urban consumers (C-CPI-U). Of the two types of CPI, the C-CPI-U is a better representation of the general public, because it accounts for about 87% of the population. On top of that, the BLS also calculates Core CPI Index, which excludes goods with volatile prices like food and energy in order to measure core inflation. Consumer prices are important because consumer buying drives the economy. CPI examines the weighted average of prices of a basket of consumer goods and services, such as transportation, food and medical care. The CPI is calculated by taking price changes for each item in the predetermined basket of goods and averaging them; the goods are weighted according to their importance. Changes in CPI are used to assess price changes associated with the cost of living.
CPI is one of the most frequently used statistics for identifying periods of inflation or deflation. This is because large rises in CPI during a short period of time typically denote periods of inflation and large drops in CPI during a short period of time usually mark periods of deflation.
Also see the Produce Price Index.