A1 Refereed original research article in a scientific journal
Stationary subspace analysis based on second-order statistics
Authors: Flumian Lea, Matilainen Markus, Nordhausen Klaus, Taskinen Sara
Publisher: ELSEVIER
Publication year: 2024
Journal: Journal of Computational and Applied Mathematics
Journal name in source: JOURNAL OF COMPUTATIONAL AND APPLIED MATHEMATICS
Journal acronym: J COMPUT APPL MATH
Article number: 115379
Volume: 436
Number of pages: 21
ISSN: 0377-0427
eISSN: 1879-1778
DOI: https://doi.org/10.1016/j.cam.2023.115379(external)
Web address : https://doi.org/10.1016/j.cam.2023.115379(external)
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/180871614(external)
In stationary subspace analysis (SSA) one assumes that the observable p-variate time series is a linear mixture of a k-variate nonstationary time series and a (p - k)-variate stationary time series. The aim is then to estimate the unmixing matrix which transforms the observed multivariate time series onto stationary and nonstationary components. In the classical approach multivariate data are projected onto stationary and nonstationary subspaces by minimizing a Kullback-Leibler divergence between Gaussian distributions, and the method only detects nonstationarities in the first two moments. In this paper we consider SSA in a more general multivariate time series setting and propose SSA methods which are able to detect nonstationarities in mean, variance and autocorrelation, or in all of them. Simulation studies illustrate the performances of proposed methods, and it is shown that especially the method that detects all three types of nonstationarities performs well in various time series settings. The paper is concluded with an illustrative example.
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