Hi guys,

I'm trying to do some analysis on some tags I have. I want ot find out the standard deviation of the tag values, but want to use the 'sample standard deviation' calculation.

The SStDev performance equation uses the 'sample' formula, but you have to enter specific values (this is not achievable in my situation)

The **StDev** performance equation allows all values within a time frame.

My question is, what formula does the **StDev** performance equation use? ie. the sample standard deviation formula or the population standard deviation formula.

Cheers

StdDev is the standard deviation over the time range given by

SStDev returns the sample standard deviation.The sample standard deviation of a sample x1, ... xn is equal to

SStDev(x1, x2 [, ... xn]) in PI Analytics takes arguments x1, ... xn

Arguments and a single array of same value type (integers and real numbers, time expressions, or time intervals)

About entering values, if you have PI AF 2018+ this becomes easy by invoking RecordedValues or other array functions as an input.

If this is a one-off calculation you could you AF Explorer, right click on the attribute, Time Series

This can be programmatically achieved in AF SDK through PIPoint.Summaries method and specifying AFCalculationBasis as PopulationStdDev