---
title: stdev()
framework: createml
role: symbol
role_heading: Instance Method
path: createml/mldatacolumn/stdev()
---

# stdev()

Returns the standard deviation of the elements in a column of doubles.

## Declaration

```swift
func stdev() -> Double?
```

## Return Value

Return Value A Double; otherwise nil if the column is invalid.

## See Also

### Getting sum, mean, and standard deviation values

- [sum()](createml/mldatacolumn/sum().md)
- [mean()](createml/mldatacolumn/mean().md)
- [std()](createml/mldatacolumn/std().md)