Some Notes on Monetary Policy Rules with Uncertainty

The author explores the role that Taylor-type rules can play in monetary policy, given the degree of uncertainty in the economy. The optimal rule is derived from a simple infinite-horizon model of the monetary transmission mechanism, with only additive uncertainty. The author then examines how this rule ought to be modified when there is uncertainty about the parameters, the time lags, and the nature of shocks. Quantitative evaluations are subsequently provided. In particular, it is shown that if the degree of persistence of inflation in the Phillips curve is not high, a simple rule such as the original Taylor rule that offsets demand shocks and puts a relatively small weight on inflation shocks may be an appropriate benchmark for the conduct of monetary policy. Conversely, it is argued that if the degree of persistence of inflation in the Phillips curve is high, then finding a Taylor-type rule that can act as a benchmark for monetary policy is likely to be difficult.