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A Betting Function for addressing Concept Drift with Conformal Martingales
Proceedings of the Eleventh Symposium on Conformal and Probabilistic Prediction with Applications, PMLR 179:219-238, 2022.
Abstract
An important issue that appears when using Conformal Martingales (CM) for detecting Concept Drift (CD), is that martingale values get very close to zero when the data generating mechanism remains the same for a large number of instances. In such cases, the martingale takes a long time to recover, resulting in detection delays or even totally failing to detect the occurrence of a CD. To address this issue we propose a new betting function we call Cautious, that avoids betting when there is no evidence that any change is taking place, therefore preventing the continuous reduction of the martingale value. The proposed betting function can be built on top of any existing betting function to mitigate the aforementioned problem. In this work, we combine it with the kernel and histogram betting functions and compare its performance with that of the two original betting functions as well as that of existing methods for addressing CD on five datasets.