stdev() (aggregation function)
Applies to: ✅ Microsoft Fabric ✅ Azure Data Explorer ✅ Azure Monitor ✅ Microsoft Sentinel
Calculates the standard deviation of expr across the group, using Bessel's correction for a small dataset that is considered a sample.
Null values are ignored and don't factor into the calculation.
For a large dataset that is representative of the population, use stdevp() (aggregation function).
Note
This function is used in conjunction with the summarize operator.
Formula
This function uses the following formula.
Syntax
stdev(expr)
Learn more about syntax conventions.
Parameters
| Name | Type | Required | Description |
|---|---|---|---|
| expr | string |
✔️ | The expression used for the standard deviation aggregation calculation. |
Returns
Returns the standard deviation value of expr across the group.
Example
The following example shows the standard deviation for the group.
range x from 1 to 5 step 1
| summarize make_list(x), stdev(x)
Output
| list_x | stdev_x |
|---|---|
| [ 1, 2, 3, 4, 5] | 1.58113883008419 |