Index Number
A statistic which assigns a single number to several individual statistics in order to quantify trends. The best-known index in the United States is the consumer price index, which gives a sort of "average" value for inflation based on price changes for a group of selected products. The Dow Jones and NASDAQ indexes for the New York and American Stock Exchanges, respectively, are also index numbers.
Let 
be the price per unit in period 
, 
be the quantity
produced in period 
, and 
be the
value of the 
units. Let 
be the estimated
relative importance of a product. There are several types of indices defined, among
them those listed in the following table.
| index | abbr. | formula |
| Bowley index |  |  |
| Fisher index |  |  |
| geometric mean index |  | ![[product((p_n)/(p_0))^(v_0)]^(1/sumv_0)](/National_Library/im_/https://mathworld.wolfram.com/images/equations/IndexNumber/Inline13.gif) |
| harmonic mean index |  |  |
| Laspeyres' index |  |  |
| marshall-Edgeworth index |  |  |
| mitchell index |  |  |
| Paasche's index |  |  |
| Walsh index |  |  |
Contact the MathWorld Team
binary tiling
