Online Change Point Detection for Multivariate Inhomogeneous Poisson Processes Time Series
Xiaokai Luo, Haotian Xu, Carlos Misael Madrid Padilla, Oscar Hernan Madrid Padilla
TL;DR
This paper addresses online change point detection in multivariate inhomogeneous Poisson point process time series with temporal dependence. It develops a scalable detector that maps each PPP observation to a finite-dimensional intensity matrix via RKHS bases and exploits a low-rank structure through a restricted SVD in a CUSUM framework, achieving single-pass operation with per-observation cost independent of the long-time horizon. The authors establish nonasymptotic, finite-sample guarantees for false-alarm control and detection delay by introducing a Matrix Bernstein inequality for geometrically $\\beta$-mixing PPPs, and they validate the approach through synthetic 3D/4D simulations and a real Oklahoma earthquake dataset, showing superior detection speed at comparable false-alarm rates. The work provides a practical, theoretically sound tool for online nonparametric change detection in complex point-process time series with broad applications in seismology, climate monitoring, and epidemiology.
Abstract
We study online change point detection for multivariate inhomogeneous Poisson point process time series. This setting arises commonly in applications such as earthquake seismology, climate monitoring, and epidemic surveillance, yet remains underexplored in the machine learning and statistics literature. We propose a method that uses low-rank matrices to represent the multivariate Poisson intensity functions, resulting in an adaptive nonparametric detection procedure. Our algorithm is single-pass and requires only constant computational cost per new observation, independent of the elapsed length of the time series. We provide theoretical guarantees to control the overall false alarm probability and characterize the detection delay under temporal dependence. We also develop a new Matrix Bernstein inequality for temporally dependent Poisson point process time series, which may be of independent interest. Numerical experiments demonstrate that our method is both statistically robust and computationally efficient.
