Incremental Variance

[blablahaha]

I'm confused with Incremental Variance in ADWIN (concept drift algorithm):

moa/moa/src/main/java/moa/classifiers/core/driftdetection/ADWIN.java

Line 390 in 7964895

incVariance = (WIDTH - 1) * (Value - TOTAL / (WIDTH - 1)) * (Value - TOTAL / (WIDTH - 1)) / WIDTH;

I found it is different with this Wikipedia Formula.

Could you help me with this?
Thanks

[abifet]

ADWIN computes variance using exponential histograms. It is explained in this paper:

http://ilpubs.stanford.edu:8090/749/

Babcock, Brian and Datar, Mayur and Motwani, Rajeev and O'Callaghan, Liadan (2003) Maintaining Variance and k-Medians over Data Stream Windows. In: ACM Symposium on Principles of Database Systems (PODS 2003), June 9-12, 2003, San Diego, California.