## How does the STDEV.S function (DAX) work?

The STDEV.S function (DAX) returns the standard deviation of a sample population.

## STDEV.S Formula Syntax

STDEV.S(
<ColumnName>
)

## How do you use theSTDEV.S function?

This function calculates the standard deviation for a sample set of data. STDEV.S replaces the older STDEV function, with the same behavior.

## Related Support Forum Posts

Confusion in using “Thin and Long Fact Table”
Normal Distribution Curve
Dax Calculation question

## Considerations when using the STDEV.S function

1. STDEV.S assumes that the column refers to a sample of the population. If your data represents the entire population, then compute the standard deviation by using STDEV.P.
2. STDEV.S uses the following formula:√[∑(x – x̃)²/(n-1)]where x̃ is the average value of x for the sample population and n is the population size
3. Blank rows are filtered out from columnName and not considered in the calculations.
4. An error is returned if columnName contains less than 2 non-blank rows.

This DAX function may return different results when used in a model that is deployed and then queried in DirectQuery mode.

## Formula examples using the STDEV.S function

=STDEV.S(InternetSales_USD[SalesAmount_USD])

=STDEVX.S(RELATEDTABLE(InternetSales_USD), InternetSales_USD[UnitPrice_USD] – (InternetSales_USD[DiscountAmount_USD]/InternetSales_USD[OrderQuantity]))

=STDEV.S(A2:A11)

## Related Course Modules 