Forty-five respondents reported a defensive gun use
in 1994 against a person (exhibit 7). Given the
sampling weights, these respondents constitute 1.6
percent of the sample and represent 3.1 million
adults. Almost half of these respondents reported
multiple DGUs during 1994, which provides the basis
for estimating the 1994 DGU incidence at 23
million. This surprising figure is caused in part
by a few respondents reporting large numbers of
defensive gun uses during the year; for example,
one woman reported 52!
A somewhat more conservative NSPOF estimate is
shown in the column of exhibit 7 that reflects the
application of the criteria used by Kleck and Gertz
to identify "genuine" defensive gun uses.
Respondents were excluded on the basis of the most
recent DGU description for any of the following
reasons: the respondent did not see a perpetrator;
the respondent could not state a specific crime
that was involved in the incident; or the
respondent did not actually display the gun or
mention it to the perpetrator.
Applying those restrictions leaves 19 NSPOF
respondents (0.8 percent of the sample),
representing 1.5 million defensive users. This
estimate is directly comparable to the well-known
estimate of Kleck and Gertz, shown in the last
column of exhibit 7. While the NSPOF estimate is
smaller, it is statistically plausible that the
difference is due to sampling error. Inclusion of
multiple DGUs reported by half of the 19 NSPOF
respondents increases the estimate to 4.7 million
DGUs.
Some troubling comparisons. If the DGU numbers are
in the right ballpark, millions of attempted
assaults, thefts, and break-ins were foiled by
armed citizens during the 12-month period.
According to these results, guns are used far more
often to defend against crime than to perpetrate
crime. (Firearms were used by perpetrators in 1.07
million incidents of violent crime in 1994,
according to NCVS data.)
Thus, it is of considerable interest and importance
to check the reasonableness of the NSPOF estimates
before embracing them. Because respondents were
asked to describe only their most recent defensive
gun use, our comparisons are conservative, as they
assume only one defensive gun use per defender. The
results still suggest that DGU estimates are far
too high.
For example, in only a small fraction of rape and
robbery attempts do victims use guns in
self-defense. It does not make sense, then, that
the NSPOF estimate of the number of rapes in which
a woman defended herself with a gun was more than
the total number of rapes estimated from NCVS
(exhibit 8). For other crimes listed in exhibit 8,
the results are almost as absurd: the NSPOF
estimate of DGU robberies is 36 percent of all
NCVS-estimated robberies, while the NSPOF estimate
of DGU assaults is 19 percent of all aggravated
assaults. If those percentages were close to
accurate, crime would be a risky business indeed!
NSPOF estimates also suggest that 130,000 criminals
are wounded or killed by civilian gun defenders.
That number also appears completely out of line
with other, more reliable statistics on the number
of gunshot cases.[14]
The evidence of bias in the DGU estimates is even
stronger when one recalls that the DGU estimates
are calculated using only the most recently
reported DGU incidents of NSPOF respondents; as
noted, about half of the respondents who reported a
DGU indicated two or more in the preceding year.
Although there are no details on the circumstances
of those additional DGUs, presumably they are
similar to the most recent case and provide
evidence for additional millions of violent crimes
foiled and perpetrators shot.
False positives. Regardless of which estimates one
believes, only a small fraction of adults have used
guns defensively in 1994. The only question is
whether that fraction is 1 in 1,800 (as one would
conclude from the NCVS) or 1 in 100 (as indicated
by the NSPOF estimate based on Kleck and Gertz's
criteria).
