The Power BI STDEV.S function is one of the DAX aggregate functions useful to find and return the standard deviation of the sample population. This article explains the DAX STDEV.S function that accepts the table column (not the expression) to return the standard deviation of the sample population and the syntax is:

STDEV.S(<Column>)

The Power BI DAX STDEV.S function works only on the numeric values and returns the standard deviation of the sample population in a column. For the entire population, use the STDEV.P.

- The STDEV.P function uses the formula √[∑(x – x˜)2 / (n-1)] where x is the sample population. Next, x˜ is the average of x, and n is the size of the population.
- The blank rows are ignored while calculating the sample population’s standard deviation.
- This function returns an error if the given column contains less than two non-blank rows.

## Power BI DAX STDEV.S function Example

We need a Measure to work with the STDEV.S function and to assign the standard deviation of the sample population. So, within the Home tab, click the New Measure button and rename it as STDEVSProfit. Please refer to the Aggregate and the function article for the remaining Power BI functions. For more Charts >> Click Here.

To demonstrate the Power BI DAX STDEV.S function, let me use the Profit column from the SuperStore Orders to obtain the sample standard deviation of the profit column.

STDEVSProfit = STDEV.S(Orders[Profit])

Please add the new STDEVSProfit Measure to the table report. Similarly, create two more measures to calculate the sample standard deviation of the Sales and orders. The other option is to add the Profit to the table click the down arrow beside it and change the aggregation to Standard deviation.

STDEVSSales = STDEV.S(Orders[Sales])

STDEVSOrders = STDEV.S(Orders[Quantity])