stdev
Standard Deviation
stdev(source, period)
Parameters
| Name | Type | Description |
|---|---|---|
source |
field | Data series |
period |
int | Number of periods |
Formula
```
STDEV = sqrt(Σ(x - mean)² / N)
Uses population standard deviation
```Examples
// volatility expanding (higher than 20 bars ago)
x = stdev(close, 20); x > x[20];
// low volatility environment
stdev(close, 14) < 2;
// volatility spike (current > 2x average)
stdev(close, 20) > sma(stdev(close, 20), 50) * 2;Returns
Non-negative float (volatility measure) ## See Also variance