Variance and standard deviation function in Drools out of the box ----------------------------------------------------------------- Key: DROOLS-1424 URL: https://issues.jboss.org/browse/DROOLS-1424 Project: Drools Issue Type: Feature Request Components: core engine Reporter: Geoffrey De Smet Assignee: Geoffrey De Smet After a bunch of research I've found the way to do this efficiently: https://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#Online_... Simply use Welford's algorithm.