Consumer Price Index - Essay Example

Prices of goods and services do not change proportionately over time. This means that some prices rise more than others and consumers substitute products and services that have become relatively less expensive. CPI overstates the cost of living by excluding the possibility of product substitution. When the quality of a good deteriorates, the value of the dollar falls, and vice versa. Because changes in the quality are hard to measure, the basket calculates prices on the assumption that quality is constant, which distorts the CPI measures.

Although the CPI is not perfect, together with other indexes like GDP deflator or PPI, it gives a relatively useful indication about the cost of living for consumers. CPI and other price indexes are used to compare dollar values over time, by taking into account the effects on inflation.