# STDEV.S

Returns the standard deviation of a sample population.

## Syntax

```
STDEV.S(<ColumnName>)
```

#### Parameters

Term | Definition |
---|---|

columnName | The name of an existing column using standard DAX syntax, usually fully qualified. It cannot be an expression. |

## Return value

A number that represents the standard deviation of a sample population.

## Exceptions

## Remarks

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.

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

Blank rows are filtered out from

*columnName*and not considered in the calculations.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 https://go.microsoft.com/fwlink/?LinkId=219171.

## Example

The following example shows the formula for a measure that calculates the standard deviation of the column, SalesAmount_USD, when the table InternetSales_USD is the sample population.

```
=STDEV.S(InternetSales_USD[SalesAmount_USD])
```