... inflation, the output gap and the real interest rate gap, defined as the difference between the real short term interest rate and estimates of the natural real interest rate. In addition, the natural ... gradually over the past 40 years, while the natural real interest rate in the US has been more stable around its long term average. The natural rate of interest in the euro area was, on average, ... log output yt, log potential output y∗t, the output gap ˜yt, the actual and the natural real rate an d the real rate gap (rt,r∗t and ˜rt) and i nflation πt. A notable featureof the...