STDEV

The STDEV function returns the standard deviation—a measure of dispersion—of a set of numeric values based on their sample (unbiased) variance.

STDEV(value, value…)

value: A number value, date/time value, or duration value or collection of these value types. All values must be of the same value type and a minimum of two values are required.

value…: Optionally include one or more additional values or collections of values.

Notes

It is appropriate to use STDEV when the specified values represent only a sample of a larger population. If the values you are analyzing represent the entire collection or population, use the STDEVP function.
The standard deviation is the square root of the variance returned by the VAR function.

Examples
Suppose you administered five tests to a group of students. You arbitrarily selected five students to represent the total population of students (note that this is an example only; this would not likely be statistically valid). Using the sample data, you could use the STDEV function to determine which test had the widest dispersion of test scores. This might be useful in determining lesson plans, identifying potential problem questions, or for other analysis. You enter the test scores into a blank table, with the scores for each student in the sample in columns A through E and the five students in rows 1 through 5. The table would appear as follows.

Examples

Suppose you administered five tests to a group of students. You arbitrarily selected five students to represent the total population of students (note that this is an example only; this would not likely be statistically valid). Using the sample data, you could use the STDEV function to determine which test had the widest dispersion of test scores. This might be useful in determining lesson plans, identifying potential problem questions, or for other analysis.

You enter the test scores into a blank table, with the scores for each student in the sample in columns A through E and the five students in rows 1 through 5. The table would appear as follows.

	A	B	C	D	E
1	75	82	90	78	84
2	100	90	95	88	90
3	40	80	78	90	85
4	80	35	95	98	92
5	90	98	75	97	88

=STDEV(A1:A5) returns approximately 22.8035085019828, the standard deviation of the results of Test 1.

=STDEV(B1:B5) returns approximately 24.5356882927706, the standard deviation of the results of Test 2.

=STDEV(C1:C5) returns approximately 9.50263121456368, the standard deviation of the results of Test 3.

=STDEV(D1:D5) returns approximately 8.07465169527454, the standard deviation of the results of Test 4.

=STDEV(E1:E5) returns approximately 3.3466401061363, the standard deviation of the results of Test 5.

Test 2 had the highest dispersion (standard deviation is a measure of dispersion), followed closely by Test 1. The other three tests had lower dispersion.

Example—Survey results
To see an example of this and several other statistical functions applied to the results of a survey, see the COUNTIF function.