The Illusion of Deterrence in Isaac Ehrlich's Research on Capital Punishment

Abstract

In this critique of Professor Ehrlich's recent research on capital punishment,' we conclude that he has failed to provide any reliable evidence that the death penalty deters murder.His data are inadequate for the purposes of his analysis and he misapplies the highly sophisticated statistical techniques he employs.We begin with an evaluation of the data he uses to measure the critical variables in his theoretical formulation and then consider flaws in his analysis which would invalidate his conclusions even if his data were adequate.We conclude by explaining how Ehrlich's analysis produces results which seem consistent with the deterrence hypothesis when in fact they are not. 2 I. Inadequacies in Ehrlich's DataThe credibility of Ehrlich's conclusions depends on the quality of the data he has used.For measures of the variables at the core of his theoretical analysis, he relies on the Uniform Crime Reporting System (UCRS) of the FBI. 3 The behavior he seeks to explain (the dependent