POST-HOC-ERGO-PROPTER - ONCE MORE AN EVALUATION OF DOES MONETARY-POLICY MATTER IN THE SPIRIT OF TOBIN,JAMES

Christina and David Romer's paper 'Does Monetary Policy Matter?' advocates the so-called 'narrative' approach to causal inference. We demonstrate that this method will not sustain causal inference. First, it is impossible to distinguish monetary shocks from oil shocks as causes of recessions. Second, a world in which the Fed only announces intentions to act cannot be distinguished from one in which it in fact acts. Third, the techniques of dynamic simulation used in the Romers' study are inappropriate and quantitatively misleading. And, finally, their approach provides no basis for establishing causal asymmetry.