The consumer price index (CPI) is an index which tracks changes in prices for basic goods and services. Consumer price indices are calculated regionally, reflecting the fact that prices are rarely stable across a nation. They are commonly used to measure inflation, and they may be utilized in other ways as well. As a general rule, the consumer price index is always on the rise, especially in a healthy economy.
To determine the consumer price index, government economists use what is known as a “market basket.” The market basket is a sampling of common goods and services. This is averaged to determine whether the cost of living is rising or falling in a given area. Economists may also track trends within the market basket. For example, they may note that food prices are rising very rapidly, and they can adjust the weighting of the consumer price index to compensate for this.
Prices naturally fluctuate over time, and the CPI is usually calculated seasonally to smooth out some of the normal changes which occur over the course of the year. If prices appear to be rising very fast, it indicates that the economy is experiencing a period of inflation. While low-scale inflation can be beneficial, rapid inflation can put consumers in a position where their wages do not keep pace with the consumer price index, making it difficult to live.
When prices drop, it reflects deflation. Deflation is often regarded as a negative for the economy, especially if it persists. However, sometimes deflation is the result of a natural market contraction after a bubble has burst. In this case, it might indicate that the market is correcting itself, and prices will eventually stabilize and start to rise again.
Statistics on the consumer price index can be found through government agencies which are responsible for keeping track of economic growth. Many such agencies keep their records online, and consumers can access very old records if they are interested in tracking changes in the CPI which have occurred over decades. It's important to remember that fluctuations from season to season can be less indicative than changes spread over a longer period of time.
As a general rule, wages and government benefits do not keep pace with inflation, because it can take time to enact changes. A spike in the consumer price index can result in hardship for citizens who are receiving wages and benefits which may be pegged to older prices.