March 26, 1997

Mervyn Susser MB BCh, Editor
American Journal of Public Health
American Public Health Association
1015 -- 15th Street NW
Washington DC 20005

Re: Hemenway D and Richardson E. "Characteristics of Automatic or
Semiautomatic Firearms Ownership in the United States." Am J. Pub
Health.

February 1997; 87(2):286-288.

Dear Dr. Susser,

In "Epidemiology Faces its Limits," Taubes' special report in
 Science,[1] New England Journal of Medicine (NEJM) Assistant Editor
 Marcia Angell acknowledged the problems that confound epidemiological
 studies that use "odds ratio" or "relative risk" statistical
 methodology. She stated, "As a general rule of thumb, we are looking
 for a relative risk of three or more [before accepting a paper for
 publication], particularly if it is biologically implausible or if it
 is a brand new finding."  In her book on the silicon breast implant
 controversy Angell stated,"[Confounding variables] can easily mask or
 falsely suggest a small risk factor. For this reason, most
 epidemiologists are very skeptical of a relative risk below 3.0 or 4.0
 if the finding is new and unanticipated. A relative risk smaller than
 this requires a good deal of confirmation.... a relative risk of 2.0
 would almost certainly be chalked up to a confounding variable or to
 some unsuspected bias."[2]  In the Science report,[1] a former
 statistical consultant for NEJM, John Bailar, an epidemiologist at
 McGill University, expressed skepticism of studies showing odds ratios
 of less than 10.

High rates of non-reporting (27.1%) in the Hemenway & Richardson
study[3] and Kellermann's[4] and others'[5] earlier work showing high
rates of inaccurate reporting of firearms ownership (12% and 13%
respectively) should have alerted the authors to the possibility, even
likelihood, that their findings were statistically inaccurate and too
insubstantial to draw meaningful conclusions.  Even if we ignored how
the odds ratios collapse to statistical insignificance in the face of
inaccurate and non-reporting of gun ownership (as Kellermann's own 2.7
odds ratio collapses to nothing when his recent gun homicide study[6]
is corrected for the reporting inaccuracy), not one of Hemenway &
Richardson's "characteristics" of certain gun owners reached Bailar's
threshold of credibility and for only one "characteristic," "owns or
carries gun for work," did the odds ratio (3.8) exceed Angell's lesser
threshold for credibility.  So, even if we credulously accepted
Hemenway & Richardson's odds ratios at face value, we are presented
with a rather uncontroversial and marginally significant observation
that police officers have a propensity to own certain firearms.

Studying primarily owners of semiautomatic firearms (as the authors
admitted), Hemenway & Richardson calculated an odds ratio of 1.89 for
"binge drinking" more than once in the 60 days preceding their survey
of gun owners. Though the "binge drinking" odds ratio of 1.89 does not
even meet the rudimentary threshold of credibility noted above,
Hemenway & Richardson spent 7 of 9 "Discussion" paragraphs focusing
upon binge drinking and gun ownership, bewailing and speculating about
a  "disturbing" finding that they have not even convincingly
demonstrated.  In contrast, their discussion section made no mention at
all of their only possible statistically significant finding, that
police are more likely to own certain guns than non-police.
Cardiovascular researcher Stanton Glantz cited more than a dozen
studies in support of his observation that "Approximately half the
articles published in medical journals that use statistical methods use
them incorrectly.  These errors are so widespread that the present
system of peer review has not been able to control them."[7]  Add the
Hemenway & Richardson study to Glantz' evidence of such statistical
incompetence.

Fifteen studies, fourteen reviewed by Kleck & Gertz[8] and the
fifteenth performed by Cook,[9] Kleck's foremost academic critic,
demonstrate one to four million or more protective uses of guns
annually, far outweighing the combined detriment of criminal, suicidal,
and careless gun misuse.  The University of Chicago Lott & Mustard
study of progressive reform of concealed handgun law allowing good
citizens to protect themselves where they are at greatest risk, outside
their homes, demonstrated that, rather than blood running in the
streets, the net outcome of these reforms has been thousands of lives
saved and violent crime prevented.[10]  In view of these findings of an
overwhelming net benefit of guns in the hands of good citizens,
Hemenway & Richardson cannot legitimately seek refuge in a special
claim of biological or other plausibility to defend their subthreshold
odds ratio.

As in this study's technically inappropriate lumping of machine-guns
rarely owned by private individuals, "automatics," with
non-machine-guns that have been commonly owned by individuals for over
a century,[11] "semiautomatics," reviewing Hemenway's prior
publications on guns demonstrates his unfamiliarity with technical and
safety issues regarding guns, an unfamiliarity that continues to
undercut his research design and conclusions. Even if Hemenway's study
design had separately inquired of the characteristics of semiautomatic
gun owners, that varied group of guns includes an overwhelming majority
of semiautomatics having magazine capacities and capabilities
approximately the same as old-fashioned cowboy "six shooters,"
indefensibly characterized by Hemenway as distinctively "rapid fire."
Noting Hemenway's published opinions on guns and gun owners begs
another question - Does Hemenway want to honestly and scientifically
study the characteristics of guns and gun owners or does he merely wish
to contribute sound bites, factoids, and demeaning images for use by
lobbyists who abhor guns and gun owners?

Collegially,
Edgar A. Suter MD
National Chair
Doctors for Integrity in Policy Research Inc.

cc:
David Hemenway PhD
Harvard School of Public Health
677 Huntington Avenue
Boston MA 02115

References

[1] Taubes G. "Epidemiology Faces its Limits." Science. July 14, 1995.
269:164-169 at 168.

[2] Angell M. "Science on Trial: The Clash of Medical Evidence and the
Law in the Breast Implant Case." New York: WW Norton & Co. 1996. at
168.

[3] Hemenway D and Richardson E. "Characteristics of Automatic or
Semiautomatic Firearms Ownership in the United States." Am J. Pub
Health. February 1997; 87(2):286-288.

[4] Kellermann AL, Rivarra FP, Banton J, Reay D, and Fligner CL.
"Validating Survey Responses to Questions about Gun Ownership Among
Owners of Reistered Handguns." American Journal of Epidemiology. 1990;
131: 1080-1084.

[5] Rafferty A, Thrush JC, Smith PK, and McGee HB. "Validity of a
Household Gun Question in a Telephone Survey." Public Health Reports.
1995; 110: 282-288.

[6] Kellermann AL, Rivara FP, Rushforth NB et al. "Gun ownership as a
risk factor for homicide in the home." N Engl J Med. 1993; 329(15):
1084-91.

[7] Glantz SA. "Biostatistics: How to Detect, Correct and Prevent
Errors in the Medical Literature." Circulation. January 1980;
61(1):1-7.

[8] Kleck G and Gertz M. "Armed Resistance to Crime: The Prevalence and
Nature of Self-Defense with a Gun." Journal of Criminal Law &
Criminology. 1995; 86(1):150-187.

[9] Cook PJ. "You Got Me: How Many Defensive Gun Uses Per Year?" a
paper presented to the American Society of Criminology meetings,
November 20, 1996. Chicago IL.

[10] Lott JR and Mustard DB. "Crime, Deterrence, and Right-To-Carry
Concealed Handguns." Journal of Legal Studies. January 1997; 26:1-68.

[11] Suter E. "'Assault Weapons' Revisited - An Analysis of the AMA
Report." Journal of the Medical Association of Georgia. May1994; 83:
281-89.