"Measuring" the impact of the stimulus

John Taylor on the Blinder-Zandi attempt to analyze the impact of government intervention.

Taylor vs. Zandi on the PBS NewsHour.

Arnold Kling critiques here and here.

My take is summed up the by the quotations marks I've put around "measuring." Blinder and Zandi don't really measure the impact of government intervention. They measure what the model says is the impact. The model is based on past relationships that were unable to predict where we are now. This quote from the CBO explaining why...