Studies of the death penalty have reached various conclusions about its effectiveness in deterring crime. But a 2008 comprehensive review of capital punishment research since 1975 by Drexel University economist Bijou Yang and psychologist David Lester of Richard Stockton College of New Jersey concluded that the majority of studies that track effects over many years and across states or counties find a deterrent effect.
Indeed, other recent investigations, using a variety of samples and statistical methods, consistently demonstrate a strong link between executions and reduced murder rates. For instance, a 2003 study by Emory University researchers of data from more than 3,000 counties from 1977 through 1996 found that each execution, on average, resulted in 18 fewer murders per county. In another examination, based on data from all 50 states from 1978 to 1997, Federal Communications Commission economist Paul Zimmerman demonstrated that each state execution deters an average of 14 murders annually.