Bayesian Online Change Point Detection for Baseline Shifts

TL;DR

This paper extends Bayesian online change point detection to handle baseline shifts in time series data, improving real-time detection of change points in dynamic environments.

Contribution

The paper introduces an extension of the BOCPD algorithm that effectively detects change points despite irreversible baseline shifts in time series.

Findings

Enhanced detection accuracy on real-world datasets

Successful application to synthetic data with baseline shifts

Visualization of the extended algorithm's effectiveness

Abstract

In time series data analysis, detecting change points on a real-time basis (online) is of great interest in many areas, such as finance, environmental monitoring, and medicine. One promising means to achieve this is the Bayesian online change point detection (BOCPD) algorithm, which has been successfully adopted in particular cases in which the time series of interest has a fixed baseline. However, we have found that the algorithm struggles when the baseline irreversibly shifts from its initial state. This is because with the original BOCPD algorithm, the sensitivity with which a change point can be detected is degraded if the data points are fluctuating at locations relatively far from the original baseline. In this paper, we not only extend the original BOCPD algorithm to be applicable to a time series whose baseline is constantly shifting toward unknown values but also visualize why the proposed extension works. To demonstrate the efficacy of the proposed algorithm compared to the original one, we examine these algorithms on two real-world data sets and six synthetic data sets.