Hump-shaped Behavior of Inflation and Dynamic Externality

This paper develops a model which can explain the hump-shaped impulse response of inflation to a monetary shock. A standard New Keynesian (NK) model is augmented so as to include dynamic externality with sticky wages and variable capital utilization. In our analysis, we assume purely forward-looking nominal rigidities in nominal prices and wages a la Calvo(1983). Nevertheless, we can show that inflation is hump-shaped under a reasonable range of parameters. It will be also shown that, in order for inflation to be hump-shaped, sticky wages and variable capital utilization are important as well as dynamic externalities.