Jim McCulloch wrote:

> In article , "Paul Barnett"
>  wrote:
>
> > With or without the presence of strict gun control in a city, Colin Loftin
> > and Ellen MacKenzie have estimated that as few as only 3% of rapes are
> > actually measured by the NCVS.  As has been noted by other people, since the
> > NCVS doesn't ask about any defensive gun use if the interviewee refuses to
> > talk about the crime, this results in a significant under-reporting.
>
> What you are saying makes no sense, Paul. First of all, the NCVS is
> precisely designed to elicit reports of crimes underreported to law
> enforcement, like rape.  Second, suppose the views of some feminists, and
> others, are correct, that rape is so horrible a crime that a vast majority
> of victims will not talk about it, even to the Bureau of the Census (or
> for that matter, if you think about it, to Kleck).  If so, then the true
> extent of rape is likely unknowable.  But (third) the unknowable is not at
> issue.  We have two figures, both derived from people who *are* willing to
> talk about it. First, we have the people who are willing to talk about it
> to the NCVS, and from that we can deduce that there are x number of
> thousands of rape victims a year. There is no reason to suppose that 40%
> of them (which I seem to remember, without looking it up, is implied by
> Kleck) resisted with guns, or that *more than 100% of them*, as a study
> says which uses Kleck's own methodology, resisted with guns.

If the NCVS doesn't survey incarcerated individuals it certainly *under* estimates
rapes, though there shouldn't be any DGUs by prisoners ;)  IIRC, prison rapes are
a substantial proportion of total rapes.  Back to non-prisoner rapes, NCVS, and
Kleck.

If the rapes are of the spousal variety and successfully fended off, again, the
NCVS respondent may decide no crime was committed and therefore not be asked about
DGU.  In some sub-cultures some domestic violence appears to be considered normal
or at least tolerated.

Second, if the respondent felt reporting a rape that was successfully defended
might lead to prosecution over the means of defense, they have a disincentive to
accurately respond to the NCVS survey.  This is true of all of the NCVS covered
crimes.  I know if I had a DGU in Chicago or New York, I wouldn't want to report
it to someone working for the government.  I *might* report it to an independent
researcher.


> What these anomalies tell us is not that the NCVS significantly
> underreports rapes, which is probably untrue, but in any case irrelevant
> (since all of the surveys under consideration derive their results from
> people who *are* willing to talk about the crime), but that studies using
> Kleck's methods are susceptible to extreme inflation in DGUs produced by a
> relatively small number of false positives.

I think it should also be noted that since Kleck & Gertz do not necessarily define
crimes the same way the NCVS does, that we should expect some discrepancies as the
definitions vary.

The NCVS was not primarily designed for estimating DGUs.  It was designed to
estimate crimes.  The design choices made (specifically the lack of anonymity
encouraging false negatives) suggest that the NCVS count is probably biased
downward in their attempt to avoid false positives.  The Kleck & Gertz methodology
has the possibility of either direction - as Jim notes in other messages, some
might not answer Kleck & Gertz for fear that the survey is really an FBI or ATF
sting.

Jim, you seem to be greatly worried about the possibility of false positives.  How
do you suggest changing the Kleck & Gertz methodology, reducing the likelihood of
false positives without encouraging (additional?) false negatives?  Or perhaps, if
you believe that false positives are such a problem and lead to significant bias,
you could devise a way to estimate the amount of bias.  Or you could work on a way
to estimate the false negatives for the NCVS data.  Bias estimation has been done
in Economics for revealed valuation, but this is a much more difficult problem.
My only suggestion would be to have the two surveys' overlap the same respondents
and see what information could be gleaned from any resulting discrepancies.


John M. Wildenthal
mailto:j-wildenthal@tamu.edu
--
"But don't do it out of emotion, and don't do it out of panic, and don't do it on
anecdotal information.  Go to experts, and then make your decision." - Sarah
Brady, responding to a query about personal defense to The Detroit Women's
Economic Club, March 11, 1997

"Much of the contemporary crime that concerns Americans is in poor black
neighborhoods and a case can be made that greater firearms restrictions might
alleviate this tragedy.  But another, perhaps stronger case can be made that a
society with a dismal record of protecting a people has a dubious claim on the
right to disarm them.  Perhaps a re-examination of this history can lead us to a
modern realization of what the framers of the Second Amendment understood: that it
is unwise to place the means of protection totally in the hands of the state, and
that self-defense is also a civil right." - Robert J. Cottroll and Raymond T.
Diamond, "The Second Amendment: Towards an Afro-Americanist Reconsideration,"
_Georgetown Law Journal,_ vol. 80, p. 361 (1991)

"If you've got to resist, you're chances of being hurt are less the more lethal
your weapon.  If that were my wife, would I want her to have a .38 Special in her
hand?  Yeah." - Dr. Arthur Kellerman, Health Magazine (March/April 1994)

"The available information does not indicate that gun control will reduce violent
crime against women.  Much of the information actually points in the opposite
direction ... gun control measures ... actually hurt women by restricting or
removing the most effective method of self-defense available ...." - "Why Annie
Can't Get Her Gun:  A Feminist Perspective on the Second Amendment," Univ. of
Illinois Law Review, 1996