The sum of a series of observations divided by the number of observations. Symbol:
. It can be calculated by the formula:

Note:

All summations are taken from 1 to . Note that the arithmetic mean is an unbiased estimate of the population mean, i.e.
is the limiting value for , as
.

Source:

PAC, 1994, *66*, 595*
(Nomenclature for the presentation of results of chemical analysis (IUPAC Recommendations
1994))
* on page 599