REGIME-SWITCHING FACTOR MODELS FOR HIGH-DIMENSIONAL TIME SERIES

We consider a factor model for high-dimensional time series with regime switching dynamics. The switching is assumed to be driven by an unobserved Markov chain; the mean, factor loading matrix, and covariance matrix of the noise process are different among the regimes. The model is an extension of the traditional factor models for time series and provides flexibility in dealing with applications in which underlying states may be changing over time. We propose an iterative approach to estimating the loading space of each regime and clustering the data points, combining eigenanalysis and the Viterbi algorithm. The theoretical properties of the procedure are investigated. Simulation results and the analysis of a data example are presented.