The Eisner Puzzle,the Unemployment Threshold and the Range of Equilibria

Using a two-regime model of the inflation-unemployment process for US data 1960:2 to 2000:2, this paper finds strong evidence to support the Eisner puzzle, which occurs when the short-run Phillips curve (SRPC) is flatter at low rates of unemployment than at higher rates. The puzzling aspect of this pattern is the expectation of excess demand to become apparent at very low rates of unemployment causing the SRPC to be steep rather than fairly flat. We show the puzzle can be resolved by estimating a three-regime model which reveals a steep SRPC at very low rates of unemployment. The estimates of the three regime model also reveal a horizontal SRPC at intermediate rates of unemployment, implying the existence of a range of equilibrium rates of unemployment at those intermediate rates.

Ian M. McDonaldEmail: