A Kernel Regression of Phillips’ Data

Economists have assumed that the Phillips curve, which shows a positive (negative) relation between inflation and the output ratio (unemployment rate), may be mapped off the aggregate demand -aggregate supply apparatus. The paper shows that the Phillips curve requires that unlikely restrictions be put on the form of the aggregate supply and aggregate demand curves. In this case, it is inappropriate to treat data on inflation and capacity utilization as the basis for estimating an underlying formal model. The paper therefore uses a nonparametric, data-driven method to describe the data. This method, of kernel regression, shows the inflation-unemployment association in Phillips’s sample to be negative on a global scale, yet irregular within particular ranges of unemployment.