StdDev

This function returns the standard deviation of up to the last specified number of values.

Syntax

StdDev ( number, count )

Remarks

The number parameter specifies the data value for which the standard deviation is to be calculated. The count parameter specifies the number of values over which to calculate the standard deviation. Any value that evaluates to –INF, INF, or NAN will be ignored. If there are no valid values stored, this function will return NAN.

The following equation is used to calculate the StdDev:

where σ(x) is the standard deviation of x, and N is the number of samples.

Example

The following example will return the standard deviation of up to the last 24 values of the variable Temp_F.

StdDev("Server:CR1000.Hourly.Temp_F",24)