Time-varying equilibrium real rates and monetary policy analysis

We show how a positive correlation between the equilibrium real interest rate (ERR) and trend growth matters for two widely debated issues in monetary policy. First, a simple Taylor rule is more robust to uncertainty about the trend growth rate than suggested by some analyses of the increase in U.S. inflation during the 1970s, because the policy mistake made when measuring the change in trend growth gets offset by the accompanying mistake in measuring the change in the ERR. Second, ignoring this correlation when estimating policy rules results in coefficients that exaggerate both the degree of interest rate smoothing and the strength of the monetary authority's response to inflation.