Excel STDEV function
Function STDEV
Description Excel STDEV function returns the sample standard deviation of a supplied set of values.
Syntax STDEV(number1, [number2], …)
number1 First numerical value or reference in the sample.
number2 [optional] Second numerical value or reference in the sample.
Example:
=STDEV(12,22,34,18)=9.291573
Average of these 4 numbers is 21.5
=SQRT(((12-21.5)^2+(22-21.5)^2+(34-21.5)^2+(18-21.5)^2)/(4-1))=9.291573
Usage Note:
The Standard Deviation is a statistical measure, which is used to calculate the amount that a set of values deviate from the average or mean value.
When the data set is a sample of a large data set then instead of the Standard Deviation, Sample Standard Deviation is used. The equation for this is:
where,
x refer to each value in the set;
x̄ is the average (statistical mean) of the set of values;
n is the number of values.