We investigate the instability problem of the covariance structure of time series by combining the non-parametric approach based on the evolutionary spectral density theory of Priestley [Evolutionary spectra and non-stationary processes, J. R. Statist. Soc., 27 (1965), pp. 204-237; Wavelets and...

In this paper two characteristics a priori contradictory and yet coexistent in the daily returns of exchange rate euro/US dollar are drawn. The non-stationarity of the covariance structure of the series is shown and, after the extraction of the unstable variance using the algorithm based on the...

This paper addresses the issue of estimating the number of breaks and their locations in the monthly US inflation series using two different approaches to testing for structural changes. The first approach considers Bai and Perron's selection procedure based on a sequence of tests. This approach...