# STDDEV_OVER_TIME

Calculates the population standard deviation of a numeric field over a specified time window.

## Syntax

`STDDEV_OVER_TIME(field, window)`

### Parameters

#### field

The metric field to calculate the standard deviation for.

#### window

The time window over which to compute the standard deviation.

## Examples

Calculates the maximum standard deviation of the `network.cost` field over time, grouping results by cluster and 1-minute time buckets.

```esql
TS k8s
| STATS max_stddev_cost=MAX(STDDEV_OVER_TIME(network.cost)) BY cluster, time_bucket = TBUCKET(1minute)
```
