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Handgun_Ban.txt
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1996-07-08
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From the Radio Free Michigan archives
ftp://141.209.3.26/pub/patriot
If you have any other files you'd like to contribute, e-mail them to
bj496@Cleveland.Freenet.Edu.
------------------------------------------------
Prohibitionists are never short of heart-rending anecdotes, but they are
ALWAYS short of data. This explains why they are constantly attempting
to resurrect studies that have already been laid to rest. There has been
a recent effort to resurrect the Loftin "study" of the 1976-77 Washington
DC gun freeze. It is my hope that this lengthy post will reacquaint
readers with the numerous major flaws in the Loftin polemic so that they
may drive a stake through the heart of the study if they encounter any
effort to resurrect the Loftin piece. A garland of garlic may also help.
*************************************************************************
* Edgar A. Suter, MD suter@crl.com *
* Chair, DIRPP Doctors for Integrity in Research & Public Policy *
*************************************************************************
The draconian Washington DC 1976-77 gun law is often inaccurately described
as a gun ban. In fact, the law was primarily a _handgun freeze_ since
existent _registered_ guns were grandfathered (the law also includes
certain stringent storage requirements even of long arms). Since new
handgun acquisitions are banned, it is understandable that some might
casually, but inaccurately, describe the law as a "ban." The freeze was
enacted in October 1976 and became effective in February 1977.
Critics of Loftin's article noted that the Washington DC homicide rates
_began_ a _gradual_ fall in 1974, two years before the DC gun freeze.
After this observation was called to Loftin's attention, Loftin responded,
but did not test that _actual_ "alternative hypothesis" of a _gradual_
decline _beginning _two_ years before the gun freeze. Instead Loftin
tested a "straw man" hypothesis, a hypothesis proposed by no one [except
Loftin], that there was an _abrupt_ decline _at_ (not "beginning") in
January 1974, almost _three_ years before the ban became effective. Loftin
claimed that publicity and discussion about the gun freeze _proposal_ might
have caused a reduction in violence even before its passage.
Since the 1976-77 law was a freeze, not a ban and confiscation, there is no
reason to expect an _abrupt_ drop. It is difficult to envision any
plausible reason for an abrupt drop (Did DC's predators suddenly get
religion and comply with the restrictions in anticipation even before
passage of the law? Were they so scared that the law _might_ be passed
that they stopped killing each other? Possible, but implausible.).
_If_ any effect were to be noticed, it would be expected to be _gradual_,
if and as the number of guns changed either downward by attrition
(grandfathered guns leave DC as the owner moves, guns become unserviceable
and unable to be replaced, etc.) or upward from the introduction of new
guns (because the law has and had no effect on the steady introduction of
new guns through illegal gun running). Loftin claims to have shown an
_abrupt_ change at November 1976, _after_ the law, but _before_ its
enactment. A gradual change is expected, but Loftin claimed to have
demonstrated an _abrupt_ change coinciding nearly exactly with enactment of
the gun freeze. There is no plausible epidemiological or other explanation
for an _abrupt_ change. Since the abrupt change violates the "rule of
biological plausibility," we have _another_ reason to be skeptical of
Loftin's claim.
The ARIMA (Automated Regressive Integrated Moving Average) method used by
Loftin generates some interesting statistical artefacts. These artefacts
allowed Loftin to contrive the appearance of a drop when no drop occurred.
In their grant proposal to CDC (to obtain tax money to subvert our civil
rights) for the DC study, Loftin discussed the ARIMA method. To
demonstrate the method, Loftin analyzed IBM stock prices during a period of
fluctuation. His "results" showed that the IBM stock fell. Statistical
models have their strengths and their weaknesses. If a statistical test
generates a result that is at variance with the primary [observed] data
collected, the statistical result is suspect. If a statistical method
makes an increase appear to be a decrease, one must explain how this could
be so. Either the primary data collection is at fault (e.g. someone did
not correctly count or enter the primary data points) or the statistical
method is at fault (e.g. computational error, the method is being
misapplied).
In the case of the Loftin article, the problem lies not with the primary
data count (nobody miscounted the _number_ of DC deaths), but with the
hypothesis, the statistical model, and/or the application of the model. As
I said in an earlier post on this subject, no statistical method turns
"black" into "white." The ARIMA analysis does not undercut the observation
the homicide rates increased every year between 1976 and 1991 (except
1985).
Numerous additional problems exist with Loftin's methods. Kleck, Cowan,
and many others have used Loftin's method to "test" a variety of
hypothetical intervention dates. Any number of random dates ("random" in
the sense that these dates do not coincide with any chronological landmarks
of the DC gun freeze) obtain the same results, an _abrupt_ "fall" in the
_number_ of homicides. Any number of dates _before and after_ the law can
be "shown" [by ARIMA artefact] to be points of _abrupt_ fall in homicide
raw numbers.
If Loftin and Mr. Van Meurs claim that _one_ of those dates of abrupt fall
- specifically the November 1976 date - was due to the gun freeze, how do
they explain the _other_ abrupt falls on _other_ random dates? "Other
causes," is the usual answer given by Loftin and his supporters --- which
is EXACTLY my point. "Other causes" explain the random date drops, "other
causes" explain the apparent drop noted by Loftin, AND "other causes"
explain the INCREASES as well AND the _apparent_ "drop" is a statistical
artefact, a spurious claim. Q.E.D.
Another problem: Loftin's method works only if you use the National Center
for Health Statistics (NCHS) data. His method fails to show a "drop" if one
uses FBI data. Why not? NCHS data does not cull out _justifiable_
homicides. Even though FBI data undercounts justifiable homicides (FBI
Uniform Crime Reports data are based on the _preliminary_ impression of the
investigating officer and suggest about 2% of homicides are justifiable. On
final analysis, about _20%_ of homicides are adjudicated as justifiable)
that small difference is enough to cause Loftin's entire analysis to
collapse. It is a bitter irony that the protective uses of guns,
justifiable homicides, provide the increment of data that allows a spurious
statistical contrivance to suggest that eliminating private gun ownership
is desirable.
Another problem: Loftin and his supporters pretend that the predominantly
white, affluent suburbs of Washington DC (that had a 25% INCREASE in
population) are an appropriate control group for overwhelmingly black,
impoverished, crack-infested urban Washington DC inner city (that had a 20%
DECREASE in population). A more appropriate control would have been a
demographically similar urban area, such as Baltimore MD.
Another problem: The population shifts (DC's decrease and the suburbs'
increase) exaggerate Loftin's ARIMA artefact.
Another problem: If one expands the baseline period (e.g. 10 years before
the law compared with 10 years after the law), Loftin's method fails to
demonstrate a drop. If you wish to invoke "other causes," I will happily
agree AND I will note that "other causes" also account for the drop
beginning two years _before_ the law AND "other causes" explain Loftin's
contrived abrupt "drop."
Bottom line: No statistical legerdemain can obscure the real world
observation that following Washington DC's 1976 gun freeze, DC's homicide
rates ROSE from 26.9 per 100,000 in 1976 to 80.6 per 100,000 in 1991. The
homicide rate rose in EVERY year between 1976 and 1991 except for 1985.
Whether the homicide rate increased _despite_ the law (the "other causes"
explanation) or _due to_ the law (by gradually disarming the victims), I
cannot say. I can say that, regardless of what reasons one may invoke,
homicide rates _inceased_ following_ the DC gun freeze to the _highest
levels _of _any jurisdiction_ at _any time_ in this nation. No rational
person can find any scientific support whatsoever for "gun control" in
these observations.
Criticism in the _medical literature_ of Loftin's article includes the
length-limited letters in New England Journal of Medicine (Letters.
"Effects of Restrictive Handgun Laws." NEJM. 1992; 326(17): 1157-61.) and
my article in JMAG (Suter E. "Guns in the Medical Literature - A Failure of
Peer Review." Journal of the Medical Association of Georgia. March 1994;
83; 133-48.). The most detailed refutation of Loftin's statistical
contrivance, however, is Kleck's presentation to the American Society of
Criminology (Kleck G. "Interrupted Time Series Designs: Time for a
Reevaluation." a paper presented to the American Society of Criminology
annual meeting. New Orleans, LA. November 5, 1992.). The paper addresses
not only the basic conceptual problems of Loftin's article, but exposes
Loftin's methodological and statistical contrivance in meticulous detail.
"Hand waving"? "proof by assertion"? I don't think so. Let the readers
decide for themselves whether or not Loftin is competent and convincing.
The articles and criticism are readily available to those interested.
The relevant excerpt from my JMAG article summarizes:
Foretelling the future - gun prohibitionists and criminals share a crystal
ball...
Loftin C, McDowall D, Wiersema B, and Cottey TJ. "Effects of Restrictive
Licensing of Handguns on Homicide and Suicide in the District of Columbia."
N. Engl J Med 1991; 325:1615-20.
methodological and conceptual errors:
*** the apparent, temporary, and minuscule homicide drop occurred 2 years
before the Washington DC law took effect
*** the "interrupted time series" methodology as used by Loftin et al.
has been invalidated
*** the study used raw numbers rather than population-corrected rates -
not correcting for the 20% population decrease in Washington, DC during the
study period or for the 25% increase in the control population -
exaggerating the authors' misinterpretations
*** the study conveniently stopped as Washington, DC's overall homicide
rate skyrocketed to 8 times the national average and the Black, male, teen
homicide rate skyrocketed to 22 times the national average
*** used a drastically dissimilar demographic group as control
*** the authors virtually failed to discuss the role of complicating
factors such as the crack cocaine trade and criminal justice operations
during the study period
Loftin et al. attempted to show that Washington, DC's 1976 ban on new gun
sales decreased murder.[1] Loftin and his co-authors, using tax money,
produced "research" with several negating flaws that were ignored or
overlooked by "peer review" and the editorial board of the New England
Journal of Medicine - perhaps a corollary of the editor's
no-data-are-needed[2] policy.
Not only has the "interrupted time series" methodology as used by Loftin et
al. has been invalidated,[3] but the temporary and minuscule homicide drop
began during 1974, 2 years before the gun law - How could the law, even
before its proposal, be responsible for the drop? Since homicidal maniacs
and criminals could not clairvoyantly anticipate the law, other causalities
should have been considered. The authors, however, side-stepped the
question and dismissed non-gun causalities without any analysis
whatsoever.
The study conveniently stopped as the Washington, DC homicide rate
skyrocketed. If the gun freeze law, which has not changed, were responsible
for the homicide drop, we would expect the "drop" to continue. If the
"guns-cause-murder" theory is valid and if the gun freeze were effective,
as "grandfathered" guns leave circulation (owner moves, dies, guns become
unserviceable, etc.), the homicide rate should drop steadily. Quite the
opposite is observed. The 1976 Washington, DC homicide rate before the law
was 26.9 (derived from population[4] and homicide[5] statistics) and then
tripled to 80.6 by 1991[6] despite or due to the law;
Justifiable and excusable homicides, including those by police officers,
were treated the same as murders and were not excluded from the study. The
study used raw numbers rather than population-corrected rates. This did not
correct for the 20% population decrease in Washington, DC during the study
period or for the 25% increase in the control population - exaggerating the
authors' misinterpretation. The study used the adjacent suburbs as a
control group, an area with demographics drastically different from the
study group.
The authors examined and allowed only a single cause interpretation - guns
are to blame. They offhandedly discarded any other possible explanation.
They specifically ignored the role of the crack cocaine trade, FBI stolen
property and Bureau of Alcohol, Tobacco and Firearms illegal weapon sting
operations in progress during the study, and measures instituted during the
study period that improved the efficiency of the Washington DC court
system. They generally ignored the role of poverty and myriad other factors
related to criminal violence.
Homicide has declined for every segment of American society except teenage
and young adult inner-city residents. The Black teenage male homicide rate
in Washington, DC is 227 per 100,000,[7] yet less than 7 per 100,000 for
rural, middle-aged white men,[8] the US group for whom gun ownership has the
highest prevalence.[9] If the "guns-cause-violence" theory is correct why
does Virginia, the alleged "easy purchase" source of all those illegal
Washington, DC guns, not have a murder rate comparable to DC?
[According to the most recent FBI Uniform Crime Reports 1993: Virginia's
homicide rate is 8.3, Washington DC's is 78.5] The"guns-cause-violence"
theory founders.
Even in their responses to criticism,[10] the authors' intransigent bias is
evident. Their position? If a drop in murder is discovered (or
statistically contrived), gun control must receive the credit, but when
attention was drawn to the failures of gun control and their study design,
the skyrocketing murder rate must be credited to "other causes." Shall we
examine gun control as science or religion? It appears that the faith of
true believers is unshakable heedless of data and the scientific method.
[1] Loftin C, McDowall D, Wiersema B, and Cottey TJ. "Effects of
Restrictive Licensing of Handguns on Homicide and Suicide in the District
of Columbia." N. Engl J Med 1991; 325:1615-20.
[2] Kassirer JP. Correspondence. N Engl J. Med 1992; 326:1159-60.
[3] Kleck G. "Interrupted Time Series Designs: Time for a Reevaluation."
a paper presented to the American Society of Criminology annual meeting.
New Orleans, LA. November 5, 1992.
[4] US Department of Commerce. Statistical Abstract of the US. - 96th.
Edition. 1976. Washington DC: US Government Printing Office.
[5] FBI. Uniform Crime Reports Crime in the United States 1976. 1977.
Washington DC: US Government Printing Office.
[6] FBI. Uniform Crime Reports Crime in the United States 1991. 1992
Washington DC: US Government Printing Office.
[7] Fingerhut LA, Ingram DD, Feldman JJ. "Firearm Homicide Among Black
Teenage Males in Metropolitan Counties: Comparison of Death Rates in Two
Periods, 1983 through 1985 and 1987 through 1989." JAMA. 1992; 267:3054-8.
[8] Hammett M, Powell KE, O'Carroll PW, Clanton ST. "Homicide
Surveillance - United States, 1987 through 1989." MMWR. 41/SS-3. May
29,1992.
[9] Kleck G. Point Blank: Guns and Violence in America. New York: Aldine
de Gruyter. 1991.
[10] Loftin C et al. Correspondence. New England Journal of Medicine.
1992; 326:1159-60.
------------------------------------------------
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