The Flattening of the Phillips Curve: Policy Implications Depend on the Cause

According to the historical relationship known as the Phillips curve, strengthening of the economy is commonly associated with increasing inflation. With inflation having only modestly picked up in the past few years as the economy has become more robust, many believe the Phillips curve relationship has weakened, with the curve becoming flatter. I show that the flattening can be due to very different types of structural changes and that knowing the type of change that has occurred is crucial for choosing the appropriate monetary policy.