New Keynesian models of the Phillips Curve generally assume a short run trade-off between inflation and a measure of excess demand due to nominal rigidities, while in the long run inflation is constant at the Non-Accelerating Inflation Rate of Unemployment (NAIRU). By contrast, models such as the Triangle Model of inflation explicitly allow for a time-varying NAIRU. We combine both approaches and estimate state-space models of the hybrid New Keynesian Phillips curve, allowing the short-run NAIRU to vary over time. Moreover, households inflation expectations are measured directly from consumer...