Index Number

Index number

A way to standardize the price changes of goods that have much different prices. For example, a consumer price index might be represented by a shopping cart of goods. Suppose those goods cost $324. The index would begin by dividing by 3.24 and the initial value would be 100. One usually watches the percentage increases or decreases in the index. See: Consumer Price Index (CPI), Time series models

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Base Value

An often arbitrary figure used as the initial value of an index. All future values of the index are comparisons against the base value. For example, suppose an index is formed in 2001 and its base value is 100. If the index is 150 in 2009, it means that its value is 50% higher in 2009 than it was in 2001. It is also called the index number. See also: Base Year.