Testing Common Deterministic Seasonality, with an Application to Industrial Production.

We propose methods to test for common deterministic seasonality, while allowing for possible seasonal unit roots. For this purpose, we consider panel methods, where we allow for individualand for common dynamics. To decide on the presence of seasonal unit roots, we introduce a decision-based approach, for which we derive the relevant critical values. We introduce anestimation method for our specific panel models. Our application concerns 16 quarterly industrial production series. One of our findings is that there is not much evidence for common deterministic seasonality.