Long term interest rates play an important role in economics and Önance due to their impact on real activity. Nevertheless, it is widely recognized that forecasting their level is di¢ cult. In the same way, modelling their link to monetary policy is not so easy even if this relationship appears crucial, as emphasized by Goodfriend (1993) for the United States. Similarly the same di¢ culty concerns the rational expectations hypothesis framework in which most empirical analyses of the term structure of interest rates are conducted. This approach postulates that long term rates are a weighted average of current and expected future short rates plus a constant term premium
