In New Keynesian models favourable cost-push shocks lower inflation and increase output. Yet, when the central bank's inflation target is not perfectly observed these shocks turn contractionary as agents erroneously perceive a temporary reduction in the target. This effect is amplified when...

This paper presents a model of monetary policy in which a rise in inflation raises uncertainty about future inflation. When inflation is low, there is a consensus that the monetary authority will try to keep it low. When inflation is high, policymakers face a dilemma: they would like to...