6  One potential contributor to the flattening of the Phillips curve is a change in the conduct of monetary policy since the 1980s toward greater stabilization of inflation and economic activity; for evidence of such a change, see Clarida, Galí, and Gertler (2000); Boivin and Giannoni (2006); and Boivin, Kiley, and Mishkin (2010).
As discussed in Roberts (2006) and Bullard (2018), greater stabilization on the part of a central bank can lead to the estimation of flatter Phillips curves in reduced-form regressions. Similarly, the adoption of an explicit inflation objective, along with greater certainty regarding the conduct of monetary policy, can help anchor longer-term inflation expectations and stabilize actual inflation in response to shocks.