Rejoinder to Peltzman

In his statements on my analysis of his "The Effects of Automobile Safety Regulation," Sam Peltzman implies that my data adjustments were "motivated only by displeasure with a particular result." Since Peltzman and I have never met nor have we corresponded other than in my request for clarification of his data adjustments, he has no basis for attributing motives to me. Anyone familiar with the literature on evaluation of motor vehicle related governmental regulations and programs would know that my research has found some of them ineffective.' I am interested in finding out which programs work to reduce human damage and which ones do not. The fact that I chose to examine the empirical evidence that Peltzman chose to test his hypothesis does not mean that I ignore the "derivation of testable hypotheses which constitute a theory," as Peltzman accuses. A theory is only tenable if the empirical data support its hypotheses. I have found that the empirical data Peltzman used in support of his hypothesis are severely and multiply flawed. Furthermore, in his reply, he continues to ignore the most important empirical evidence regarding the effects of state and federal motor vehicle safety regulations. The reification of a theory to the point of ignoring data that contradict its hypotheses is not uncommon among scientists. However, the scientist who does so often loses credibility along with his theory. I regret that Peltzman has ignored that basic truth.