Point Blank, by Gary Kleck, pg 165, citing a study by Wilson and Sherman, 1961:
“At least one medical study compared very similar sets of wounds (‘all were
penetrating wounds of the abdomen’), and found that the mortality rate in
pistol wounds was 16.8%, while the rate was 14.3% for ice pick wounds and
13.3% for butcher knife wounds.
The study is in Annals of Surgery Vol 153 pp 639-649 “Civilian
Penetrating Wounds of the Abdomen” by Wilson and Sherman. It covers stab
(5% mortality) and gun shot wounds (17% mortality) to the abdomen.
The numbers Kleck quotes above come from Table 7 of the article which
contains mortality data by weapon. The implication seems to be that
“knives are almost as deadly as guns”. This is extremely misleading.
There are two basic questions to be answered:
Exactly what was measured?
Is the result statistically significant?
(1) The data is from 452 admissions with abdominal wounds to a
hospital in Memphis, Tennessee over the period 1948-1959.
(1a) People who died before reaching hospital are NOT counted. In the
discussion following the paper it is stated that “the preponderance of
stab wounds is more apparent than real because a significant
percentage of patients wounded by gunshot die before reaching the
hospital.”, so this will make the mortality rate for gunshot wounds
appear to be less.
(1b) The wounds include self-inflicted and accidental cases. Someone
attempting suicide with a gun will probably aim at the head, but a
a would-be knife suicide may well attempt disembowelment.
(1c) Mortality rates for wounds to other parts of the body may well be
very different. For example, a low velocity weapon like a knife is
far less likely to penetrate a skull than a high velocity projectile.
(1d) The distribution of wounds is different for knife assaults and
gun assaults, since victims of knife assaults have more chance to
dodge and block.
(1e) Medical treatment has improved since 1948. More recent results
on abdominal wound mortality (Annals of Surgery 179 pp 639) show that
stab wounds are 1% lethal and gun shot wounds are 13% lethal.
(1f) The weapon used was known for only some of the cases. The
mortality rate for gunshot wounds where the type of gun was unknown
was 29%, so this made the mortalities for each type of gun appear to
be lower than they really were.
(2) The 13.3% death rate for butcher knife wounds is based on a mere 15
cases. This is far too few to give a meaningful mortality rate. The
death rate for rifle wounds was 7.7% (based on only 26 cases). Do
you think rifles are half as lethal as handguns?
I have calculated 95% confidence intervals for each of the weapons in
the paper. Here are the results:
Weapon Cases Deaths % Deaths 95% conf for mortality rate Shotgun 49 10 20.4 11%-34% Pistol 101 17 16.8 11%-25% Ice Pick 14 2 14.3 4%-40% Butcher Knife 15 2 13.3 4%-38% Rifle 26 2 7.7 2%-24% Switch-blade knife 17 1 5.9 1%-27% Pocket knife 44 0 0 0%-8% Unknown GSW 14 4 28.6 12%-55% Other stab 172 9 5.2 3%-10% All GSW 190 33 17.4 13%-23% All stab 262 14 5.3 3%-9%
We see that mortalities for each pointed weapon are not significantly
different from mortalities for all pointed weapons, but that
mortalities for stab wounds are significantly less than mortalities from gun
95% confidence intervals for mortalities calculated from (Annals of
Surgery 179 pp 639) are 1%-2% for abdominal stab wounds, and 11%-15%
for abdominal gun shot wounds.