Robust Monetary Policy in the New-Keynesian Framework

We study the effects of model uncertainty in a simple New-Keynesian
model using robust control techniques. Due to the simple model structure, we
are able to find closed-form solutions for the robust control problem, analyzing
both instrument rules and targeting rules under different timing assumptions.
In all cases but one, an increased preference for robustness makes monetary
policy respond more aggressively to cost shocks but leaves the response to
demand shocks unchanged. As a consequence, inflation is less volatile and
output is more volatile than under the non-robust policy. Under one particular
timing assumption, however, increasing the preference for robustness has no
effect on the optimal targeting rule (nor on the economy).