Testing for linearity in time series models has been an active area of research [see Granger and Terasvirta (1993), Tong (1991)]. The authors consider a test for linearity against a particular regime switching model known as the smooth transition autoregressive (STAR) model.

Recently, it has been shown that seasonal and business cycles are related and a similar economic mechanism is at work in producing both types of cycles. Thus, an analysis of seasonal fluctuations shed light on the nature of the business cycle. This paper uses the LM-type tests proposed by Canova...