Change-Point Detection in Time-Series Data by Relative Density-Ratio   Estimation
  The objective of change-point detection is to discover abrupt property changes lying behind time-series data. In this paper, we present a novel statistical change-point detection algorithm based on non-parametric divergence estimation between time-series samples from two retrospective segments. Our method uses the relative Pearson divergence as a divergence measure, and it is accurately and efficiently estimated by a method of direct density-ratio estimation. Through experiments on artificial and real-world datasets including human-activity sensing, speech, and Twitter messages, we demonstrate the usefulness of the proposed method. 
Song Liu, Makoto Yamada, Nigel Collier, Masashi Sugiyama
stat.ML cs.LG stat.ME