Seasonal fractional integration with structural break. An application to the German GNP data

This paper deals with the analysis of the German nominal GNP quarterly data (1973q1 – 1996q4) using a new approach based on seasonal fractional integration that allows us to incorporate a structural break that is endogenously determined by the model. The results show that the break occurs at 1990q2, the time of the German re-unification, and the order of integration is slightly above 1 before the break, and strictly smaller than 1 (though highly persistent) after the unification.