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Thursday, February 1, 2018

#AnomalyDetection vs. #NoveltyDetection. SETDS Method Detects and Separates both

Reading "Anomaly detection with Apache MXNet":

"An important distinction has to be made between anomaly detection and “novelty detection.” The latter turns up new, previously unobserved, events that still are acceptable and expected. For example, at some point in time, your credit card statements might start showing baby products, which you’ve never before purchased. Those are new observations not found in the training data, but given the normal changes in consumers’ lives, may be acceptable purchases that should not be marked as anomalies."

I figured out that my SETDS method has this Novelty Detection included as my

EV based trends detection  method (e.g. implemented in R as "TrendieR") finds recent change points in the time-serious data and then by building trend-forecast checks if the change is permanent or not. So if it is permanent the possible "novelty" is detected.  



So the 1st part of SETDS  (e.g. implemented as "SonR" on R) captures just anomalies and/or outliers, then Trend detection separates cases that indicate the possible "novelty". (something changed and stays changed and growing). Still false positive could be there though.... 

BTW there is a 3rd level of SETDS which is actually the way to correlate performance data with demand (drivers) data  to build meaningful forecasts (e.g. implemented as "Model Factory")