CPI

A consumer price index (CPI) is a statistical estimate of the level of prices of goods and services bought for consumption purposes by households. It is calculated as the weighted average price of a market basket of consumer goods and services. Changes in CPI track changes in prices over time. The items in the basket are updated periodically to reflect changes in consumer spending habits. The prices of the goods and services in the basket are collected (often monthly) from a sample of retail and service establishments. The prices are then adjusted for changes in quality or features. Changes in the CPI can be used to track inflation over time and to compare inflation rates between different countries. While the CPI is not a perfect measure of inflation or the cost of living, it is a useful tool for tracking these economic indicators. It is one of several price indices calculated by many national statistical agencies.

A CPI is a statistical estimate constructed using the prices of a sample of representative items whose prices are collected periodically. Sub-indices and sub-sub-indices can be computed for different categories and sub-categories of goods and services, which are combined to produce the overall index with weights reflecting their shares in the total of the consumer expenditures covered by the index. The annual percentage change in the CPI is used as a measure of inflation. A CPI can be used to index (i.e., adjust for the effect of inflation) the real value of wages, salaries, and pensions; to regulate prices; and to deflate monetary magnitudes to show changes in real values. In most countries, the CPI is one of the most closely watched national economic statistics.