Purely forward-looking versions of the New Keynesian Phillips curve (NKPC) generate too little inflation persistence. Some authors add ad hoc backward-looking terms to address this shortcoming. We hypothesize that inflation persistence results mainly from variation in the long-run trend component of inflation, which we attribute to shifts in monetary policy. We derive a version of the NKPC that incorporates a time-varying inflation trend and examine whether it explains the dynamics of inflation. When drift in trend inflation is taken into account, a purely forward-looking version of the model fits the data well, and there is no need for backward-looking components. (JEL E12, E31, E52)
A Response to Cogley and Sbordone's Comment on 'Closed-Form Estimates of the New Keynesian Phillips Curve with Time-Varying Trend Inflation'