Thursday, February 07, 2013

DEATH PENALTY DETERRENCE: Rebuttal to Donahue and Wolfers (D&W)

Dudley Sharp

RE: Uses and Abuses of Empirical Evidence in the Death Penalty Debate, John J. Donohue & Justin Wolfers, Vol 58, Issue 3, Stan. L. Rev. 791 Article, Dec 2005


“Had (D&W’s) paper been subjected to the normal blind peer review process in an authoritative economic journal it is highly unlikely that it would have survived intact , if at all. ”

“D&W’s unsupported claim that the appropriate variable in studies of deterrence using these borrowed tools from portfolio analysis is the amount or level of homicides in the respective jurisdictions. This claim is without theoretical basis or empirical precedent. ”

“With regard to DW’s specific comments on our two papers (Cloninger & Marchesini, 2001 & 2006) we find very little requiring defense. Implicit in their critique, and explicitly stated in private communications, DW were able to replicate our results based on data we furnished, at their request, as well as data they acquired independently. ”

“(D&W’s) Quibbling over numerous and sometimes meaningless statistical issues obscures the picture painted by the cumulative effect of the nearly dozen studies published since the turn of the 21st century.”

“Using differing methodologies and data sets at least five groups of scholars each working independently (and often without knowledge of the others) have arrived at the same conclusion, there is significant and robust evidence that executions deter some homicides. While there may be merit in some of (D&W’s) specific criticisms, none addresses the totality of the collection of studies. The probability that chance alone explains the coincidence of these virtually simultaneous conclusions is negligible.”

“Reflections on a Critique”, Dale O Cloninger and Roberto Marchesini, forthcoming Applied Economic Letters (likely 2007)


(2006) ” . . . D&W do not even report Zimmerman’s “preferred” results correctly, and then proceed by carrying on this error throughout the remainder of their critique.”(pg8)

“It is shown that D&W made a number of serious misinterpretations in their review of Zimmerman’s study and that none of the analyses put forward by D&W (which ostensibly refute Zimmerman’s original results and conclusions) hold up under scrutiny. (pg8)

” . . . D&W’s method of interpreting their results is not consistent with that proscribed by the received econometric literature on randomized testing . . .”. “As such, D&W’s interpretation of their randomized test in itself does not (and cannot) reasonably lead one to conclude that Zimmerman’s estimates suggesting a deterrent effect of capital punishment are spurious.” (pg12)

” . . . D&W do not appear to have interpreted their randomization test in any meaningful fashion.” (pg14)

” . . . (Donohue and Wolfers’ “D&W”) criticisms of Zimmerman’s analysis are misrepresentative, moot or unsupportable in terms of the analyses they perform.” “It is shown that Zimmerman’s published empirical results, or the conclusions drawn from them, are not in any way refuted by D&W’s critique.” (pg 3)

“This later estimate suggests that each execution deters 14 murders on average . . .”. (pg 7)

“Of course, (D&W’s) omission tends to create a strong impression that Zimmerman’s analysis ‘purports to find reliable relationships between executions and homicides’, when his actual conclusions regarding the deterrent effect of capital punishment are far more agnostic.” (pg10)

” . . . the state clustering correction employed by D&W may not be producing statistically meaningful results.” (pg16)

“And while D&W once lamented that recent econometric studies purporting to demonstrate a deterrent effect of capital punishment yield ‘heat rather than light’, as shown herein, their criticisms of Zimmerman (2004) tend to yield ‘smoke rather than fire’.”(pg26)

Zimmerman, Paul R., “On the Uses and ‘Abuses’ of Empirical Evidence in
the Death Penalty Debate” (November 2006). ssrn(dot)com/abstract=948424


(2006) “(D&W’s) analysis shows that attempts to make the deterrence effect disappear are ineffective.” (p 16)

— The criticism of our studies is flawed and does not effect the strength of the measured deterrent effect.
— Existence of the death penalty, in law, has a statistically significant impact on reducing murders. (p 23)
— Execution rates show significant impact in reducing murders. (p 13 & 23)
— Death row commutations, and other removals, increase murders. (p13 & 23)

“The Impact of Incentives On Human Behavior: Can we Make It Disappear? The Case of the Death Penalty”, Naci H. Mocan, R. Kaj Grittings, NBER Working Paper, 10/06, www(dot)


Abstract: The academic debate over the deterrent effect of capital punishment has intensified again with a major policy outcome at stake. About two dozen empirical studies have recently emerged that explore the issue. Donohue and Wolfers (2005) claim to have examined the recent studies and shown the evidence is not robust to specification changes. We argue that the narrow scope of their study does not warrant this claim.

2007 – Hashem Dezhbakhsh & Paul H. Rubin
From the ‘Econometrics of Capital Punishment’ to the ‘Capital Punishment’ of Econometrics: On the Use and Abuse of Sensitivity Analysis (September 2007). Emory Law and Economics Research Paper No. 07-18,
2010 Applied Economics

“From the ‘econometrics of capital punishment’ to the ‘capital punishment’of econometrics: on the use and abuse of sensitivity analysis”

Hashem Dezhbakhsha; Paul H. Rubina, a Department of Economics, Emory University, Atlanta, GA 30322, USA   First published on: 21 October 2010

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