Periodic models for seasonal data allow the parameters of the model to vary across the different seasons. This paper uses the components of UK consumption to see whether the periodic autoregressive (PAR) model yields more accurate forecasts than non-periodic models, such as the airline model of Box and Jenkins (1970), and autoregressive models that pre-test for (seasonal) unit roots. We analyse...

A lot of time series analysis in economics and nance is to determine whether a unit root and/or seasonal unit root is present in the data. These tests are usually based on unit root tests orginally developed by Dickey & Fuller(1981). Testing for the presence of a seasonal root has been considered by Dickey, Hasza & Fuller (1984). Li(1991) considered tests for the existence of a seasonal and a r...

We consider the problem of testing for seasonal unit roots in monthly panel data. To this aim, we generalize the quarterly CHEGY test to the monthly case. This parametric test is contrasted with a new nonparametric test, which is the panel counterpart to the univariate RURS test that relies on counting extrema in time series. All methods are applied to an empirical data set on tourism in Austri...