# STDEVX.S Function (DAX)

Owen Duncan|Last Updated: 10/5/2018
|
1 Contributor

Returns the standard deviation of a sample population.

## Syntax

``````STDEVX.S(<table>, <expression>)
``````

#### Parameters

table
Any DAX expression that returns a single scalar value, where the expression is to be evaluated multiple times (for each row/context).

expression
Any DAX expression that returns a single scalar value, where the expression is to be evaluated multiple times (for each row/context).

## Return Value

A number with the standard deviation of a sample population.

## Remarks

1. STDEVX.S evaluates expression for each row of table and returns the standard deviation of expression assuming that table refers to a sample of the population. If table represents the entire population, then compute the standard deviation by using STDEVX.P.

2. STDEVX.S uses the following formula:

√[∑(x - x̃)²/(n-1)]

where x̃ is the average value of x for the entire 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. For more information about semantic differences in DirectQuery mode, see http://go.microsoft.com/fwlink/?LinkId=219171.

## Example

The following example shows the formula for a calculated column that estimates the standard deviation of the unit price per product for a sample population, when the formula is used in the Product table.

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