Yesterday the New York Times published an article about simulations of the effects of fiscal stimulus packages and financial interventions using an old Keynesian model. The simulations were reported in an unpublished working paper by Alan Blinder and Mark Zandi. I offered a short quote for the article saying simply that the reported results were completely different from my own empirical work on the policy responses to the crisis.
I have now had a chance to read the paper and have more to say. First, I do not think the paper tells us anything about the impact of these policies. It simply runs the policies through a model (Zandi’s model) and reports what the model says would happen. It does not look at what actually happened, and it does not look at other models, only Zandi’s own model. I have explained the defects with this type of exercise many times, most recently in testimony at a July 1, 2010 House Budget Committee hearing where Zandi also appeared. I showed that the results are entirely dependent on the model: old Keynesian models (such as Zandi’s model) show large effects and new Keynesian models show small effects. So there is nothing new in the fiscal stimulus part of this paper.