stdev() (aggregation function)

Applies to: ✅ Microsoft FabricAzure Data ExplorerAzure MonitorMicrosoft 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.

Image showing a Stdev sample 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