dgu
tlambert | February 24, 2002Lowell Savage writes:
Sorry, Ron. Much as I agree with your position, I have to say that you
haven't addressed Tim's issue: why is it that 37% of non-gun defenders were
injured before they began self-defensive actions while only 13% of gun
defenders were injured before they began self-defense actions?
Perhaps an anecdote from a column by Ann Coulter could illuminate a possible
explanation. Ann said that she was walking alone over a bridge toward her
apartment (or is it a condo? And no I don't remember why she was doing this
alone, at that time.) when she saw a man coming toward her from…
tlambert | February 20, 2002In "Point Blank", Kleck analyzed NCVS data and found that while 38% of
people who used any means of self-protection against robbers were
injured in the encounter, only 17% (the lowest for any means for
self-protection) of people who use a gun for self-defence against
robbers were injured. Kleck claimed that this showed that guns were
the most effective means for avoiding injury.
In their critique of "Point Blank" Alba and Messner point out the flaw
in Kleck's reasoning -- the evidence from the NCVS is equally well
explained if injury makes victims less likely to use guns. Kleck
dismisses…
tlambert | June 22, 1999Ray writes:
Danny's obvious reading disability has not allowed him to
read this when I posted it before. Maybe he can get a friend to
read it to him this time:
W A Collier writes:
Ray, one question for you: If all these other folks including Marvin E.
Wolfgang (widely acclaimed as a statistician) found no fault serious
enough to invalidate the methodology of Kleck, then how do you account
for your posting? Are you a better analyst than Wolfgang and Kleck/Gertz
- or are you simply making up a some of this, cutting bits and pieces
from their contexts, and then changing contexts (as I have…
tlambert | June 22, 1999W A Collier writes:
How the NCVS miscounted DGUs
Undersized sample, poor methodology, bias in the questions, unsound
methods and procedures in eliminating bias, and unlike Kleck, they
started with the conclusion (there are only a small number of gun
defenses) as an objective to be proven (not the scientific method)
whereas Kleck started with the question (How many DGUs are there) and let
the numbers supply the answer, pro or con.
You need to inform yourself better about the NCVS.
The sample size is about 100 times that of Kleck's survey.
The NCVS methodology has been refined over 25 years…
tlambert | June 11, 1999I argued that the estimate of 200,000 DG woundings derived from
Kleck's survey (p163 of TG) was inconsistent the estimate of
7700-18,500 DG woundings on page 164 of TG. Kleck accuses me of
sloppy reading for not noting that the p 164 estimate is for medically
treated wounds only. However, even if we accept Kleck's generous
estimate that there are as many untreated gunshot wounds as treated
ones (chapter 1 of TG), it is quite clear that if we multiply the page
164 estimate by two to allow for this possibility, that it is still
not at all close to the estimate from Kleck's survey.
In any case…
tlambert | June 10, 1999Gary Kleck writes:
my position that estimates of DGUs with a wounding are unstable is
correct. The prevalence of DGUs with a wounding in the Kleck-Gertz
(K-G) survey was 0.0011 (1.326% of U.S. adults had a DGU of some
kind in the previous year, and 8.3% of DGUs involved a wounding --
see pp. 184-185 of K-G article; 0.083 x 0.01326 = 0.00110058).
Assuming simple random sampling, the 95% confidence interval
estimate of the national annual prevalence of DGUs with a wounding
would be 0.0011 +/- 1.96((.0011 x .9989)/4,977)) = 0.0011 +/- 0.0009,
or 0.000179-0.00202.
This is not the correct way to…
tlambert | July 29, 1998I used to believe that Kleck's estimate of DGU's was correct, but
overwhelming evidence to the contrary has convinced me otherwise.
Sam A. Kersh writes:
To the best of my knowledge, you have never accepted Kleck's DGU
estimates. At least not in the last 5 years that you and I (and Pim)
have debated guns, crime and 'Point Blank.'
Here's what I wrote about it back in 1991:
A most interesting paper! Like any good scientific paper it raises a lot of
questions. The estimate of 1M defensive uses arises from about 50 (4% of
1228) yes respondants. Don't you just want to have a follow-up survey…
tlambert | June 5, 1998Dr. Paul H. Blackman writes:
Just a very few comments: Folks can report an incident to the police
without reporting gun use. I once fetched a gun to encourage some
burglars to leave, and reported the burglary but not the gun use,
since the gun possession was unlawful.
The Kleck estimate is not just inconsistent with police records of gun
use against crime, but with police records of crime. There were
300,000 DGUs amongst the robberies known to the police? Are we to
suppose that criminals seek out armed victims.
Kleck/Gertz have a nice response to the ludicrous Hemenway reliance
on…
tlambert | June 3, 19980. Introduction
Volume 87:4 of the Journal of Criminal Law and Criminology contains
three articles on the issue of the frequency of defensive gun use.
The first presents David Hemenway's critique of Gary Kleck's 2.5
million estimate, the second is Kleck and Gertz's reply and finally
Tom Smith of the National Opinion Research Center comments on both
papers.
I'll try to summarize the arguments and comment where I think they are
wrong.
1. Hemenway's critique
1a. False Positives
Hemenway's critique has two main arguments. The first is the problem
of false positives. Let me define some terms…
tlambert | May 8, 1998John Briggs writes:
Also, the Crime Incident Report that follows the Basic Screen Questionnaire
seems to elicit details (including defensive responses) regarding only the
most recent of multiple similar reported crime incidents. Questions 2 and 3
ask about the when and where of "this/the first incident" and question 4
asks "Altogether, how many times did this type of incident happen during
the last 6 months?" Then, item 5a states "The following questions refer
only to the most recent incident" and the rest of the questions in the CIR,
including those regarding defensive actions, appear to be…
tlambert | May 7, 1998Note that even if you are in love with Kleck's estimate for DGUs, you
can't honestly compare it with the NCVS estimate for gun crimes, since
it is not possible for both Kleck's estimate for DGUs and the NCVS
estimate for gun crimes to be correct.
Dr. Paul H. Blackman writes:
Why not? NCVS's purpose is to measure crimes, not defensive gun
uses. Why can't one think the NCVS does a pretty good job measuring
what it's trying to measure, and Kleck-Gertz did a pretty good job
measuring what they were trying to measure? Kleck did, of course;
Kleck does not seem to have noticed that his "generous…
tlambert | September 24, 1997A large number of criminal shootings are
"drive-bys" --- fired from long range and more likely to hit an
extremity than a self-defence shooting at close range. These factors
suggest that defensive shootings would be more lethal than criminal ones.
John Briggs writes:
Any data on the proportions of such long range shootings? I confess I have
not seen a serious treatment of the topic. News acounts leave one with the
impression that such shootings involve whole carloads of machinegun
equipped gangbangers. Our streets aren't that wide here in the US. We
aren't talking 100 yard firefights.…
tlambert | September 15, 1997John Briggs writes:
[Calculation of number of justifiable shootings deleted]
This would suggest 15,000 to
20,000 civilian justifiable woundings or 17,500 to 22,500 incidents in
which a civilian shot and hit an assailant.
Kleck does a similar calculation in "Point Blank" to get an estimate
of 10,000 to 20,000.
For reasons I allude to below I am inclined to believe that civilian DGUs
would be likely to result in a significantly lower killed-to-wounded ratio
than would criminal gun use. The 10% to 15% lethality ratio of gunshots may
lump together much higher kill-ratio criminal shootings…
tlambert | September 10, 1997John Briggs writes:
[Calculation of number of justifiable shootings deleted]
This would suggest 15,000 to
20,000 civilian justifiable woundings or 17,500 to 22,500 incidents in
which a civilian shot and hit an assailant.
Kleck does a similar calculation in "Point Blank" to get an estimate
of 10,000 to 20,000.
(This represents an awfully
high figure if there are only 80,000 civilian DGUs as the NCVS reports--of
course, the NCVS could be low.)
As you have noted, if we know A, the fraction of DGUs where the
defender shot at the criminal, and B, the fraction of DGUs where one
or more of the…
tlambert | September 9, 1997SFBearCop wrote:
I can think of a number of reasons, none of them noble, why someone would
fabricate a DGU, starting with giving the pollster what they thought was
wanted. People do it all the time, so a friend in the public-opinion-counting
game told me thirty or more years ago.
John Briggs writes:
This would account for some false positives in the DGU surveys. It would
also be present, presumably, in NCVS responses. The question is why are the
response rates so different?
The DGU question appears quite early in Kleck`s survey. It's not hard
for a person to guess that it is the important…
tlambert | September 7, 1997Peter Boucher writes:
Just in case anyone's interested.
Copied from Kleck/Gertz, here are the polls from table 1
(minus those with no estimate of annual DGUs):
Survey, Where, What year, What kinds of guns, # DGUs
Field, California, 1976, just handguns, 3.1M
Bordua, Illinois, 1977, all guns, 1.4M
DMIa, U.S., 1978, all guns, 2.1M
DMIb, U.S., 1978, all guns, 1.1M
Hart, U.S., 1981, just handguns, 1.8M
Ohio, Ohio, 1982, just handguns, 0.8M
Mauser, U.S., 1990, all guns, 1.5M
Gallup, U.S., 1991, all guns, 0.8M
Gallup, U.S., 1993, all guns, 1.6M
L.A.Times, U.S., 1994, all guns, 3.6M
Tarrance, U.S.,…
tlambert | September 4, 1997"Eugene Volokh" writes:
but I was wondering what you thought about the NCVS
point I raised again a few days ago. To my knowledge, waiting for
respondents to volunteer information is generally considered rather
bad survey practice; and we saw that with the rape statistics
shifting to a direct question changed the total by about a factor of
2.5 or 3, if I recall correctly.
I have even been told -- entirely outside the defensive gun use
context -- that the trick is cuing as often as possible: Asking the
question directly, several times, in subtly different ways, to
trigger people's memories…
tlambert | September 4, 1997Dr. Paul H. Blackman writes:
I was curious about the suggestion that hardly
anyone could possibly still believe the Kleck
data now that NSPOF had become the 15th or 16th
such survey in the same general category.
Then you seem to have misunderstood. Kleck's estimate (not his data -
I have no problem with his data, just his interpretation of it) is not
credible because it fails every single cross check of its validity.
It is inconsistent with:
CDC counts of homicides
UCR counts of homicides
Kleck's own, earlier, estimate of defensive woundings
Kleck's own, earlier, estimates of defensive…
tlambert | August 14, 1997Peter Boucher writes:
Tim wrote that he, at first, agreed with the Kleck DGU estimates, but has
since been convinced by the evidence that they were wrong.
Tim, I've known you (well, sort of) for over 5 years, and I've never
seen you post anything that indicated that you agreed with Kleck's DGU
estimates. Did you change your mind more than five years ago? What
was the evidence that forced you to change it?
I first encountered one of Kleck's estimates in his paper published in
"Social Problems". This was in 1989, soon after I first started
posting to talk.politics.guns. In this paper he…
tlambert | August 10, 1997"Eugene Volokh" writes:
I should say that I agree with some of your criticisms of the Kleck
& Gertz results, and of the 1.5 million count arrived at by the
NSPOF study;
In case anyone remains who finds the Kleck estimate credible, let me
make a couple more observations:
On page 170 Kleck "generously" estimates that there are about 550,000
gun crimes each year. According to his survey, in about 18% of his
2.5M DGUs, the offender was armed with a gun. That's about 450,000
gun crimes. Apparently we are supposed to believe that in 90% of gun
crimes the victim gets to use a gun for…