The aim of this paper is to set out criteria for defining trend and seasonal components in a time series. The criteria are set up primarily in terms of properties involving prediction. Because a structural time series model is set up in terms of components of interest, the relevant information...

This article reports the results of fitting unobserved components (structural) time series models to data on real income per capita in eight regions of the United States. The aim is to establish stylised facts about cycles and convergence. A new model is developed in which convergence components...