Myth: A gun in the home increases personal safety.
Fact: A gun in the home make homicide 2.7 times more likely.
Summary
Keeping a gun in the home carries a murder risk 2.7 times
greater than not keeping one, according to a study by Arthur Kellermann.
The National Rifle Association has fiercely attacked this study,
but it remains valid despite its criticisms. The study found that
people are 21 times more likely to be killed by someone they know
than a stranger breaking into the house. Half of the murders were
over arguments or romantic triangles. The study also found that
the increased murder rate in gun-owning households was entirely
due to an increase in gun homicides only, not any other murder
method. It further found that gun-owning households saw an increased
murder risk by family or intimate acquaintances, not by strangers
or non-intimate acquaintances. The most straightforward explanation
is that the presence of a gun increases the possibility that a
normal family fight or drinking binge will become deadly. No other
explanation fits the above facts.
Argument
Most people keep guns in their homes for self-protection.
The image of an unknown criminal breaking into your house is an
important one for gun advocates, because it justifies keeping
a gun in the home. But to gun control advocates, a gun in the
home means that a family fight or a drinking binge is more likely
to turn deadly. Which view is more accurate?
In an attempt to answer this question, a team led by Dr. Arthur
Kellermann of Emory University conducted a survey of 388 homes
that had experienced homicides. (1) They found that 76.7 percent
of the victims were killed by a spouse, family member or someone
they knew, and there was no forced entry into the home 84.3 percent
of the time. Strangers comprised only 3.6 percent of the killers.
However, the killer was never identified in 17.4 percent of the
cases.
Of the 420 homicides they originally investigated, 96.4 percent
were illegal. Only 3.6 percent were ruled legally excusable homicide
(that is, self-defense).
After eliminating the impact of other variables like illegal drugs
and domestic violence, the researchers found that the risk of
getting killed was 2.7 times greater in homes with a gun than
without them. No protective benefit of possessing a firearm was
ever found, not even for a single one of the 14 subgroups studied.
Needless to say, the National Rifle Association and other pro-gun
advocates have fiercely attacked this survey. Kellermann's work
has been branded "junk science," "unpublishable,"
"biased," "seriously flawed," "fraudulent"
and "grand malpractice." The NRA also criticized the
Centers for Disease Control for continuing to fund such anti-gun
research, and the Republican Congress pressured the CDC to shut
it down completely. Thus, the reaction of Republicans and the
NRA to this controversial study was not to call for more studies
to clarify the issue, but to censor all further scientific research.
Pro-gun advocates respond that they are not promoting censorship,
only objecting to wasting tax dollars on blatantly biased, deeply
flawed research. Pro-gunners feel that the sound bites generated
by this study will become part of a popular mythology against
guns that will be hard to correct. But this objection is based
on a faulty view of the research method. The best way to correct
bad science is to subject it to expert criticism: namely, peer
review. Kellermann's study was, and it passed. Pro-gunners might
then wish to criticize the peer review process. For example, they
might accuse Kellermann's peer reviewers of sharing his bias (although
there are protocols in peer review to avoid this). The principled
response, then, would be to examine and reform the peer review
process. For example, Republicans in Congress might have called
for pro-gun criminologists like Gary Kleck to be included in all
future peer review of CDC-funded studies. Another principled response would be
for the NRA -- one of the richest organizations in America --
to start funding its own research by way of rebuttal. But to shut
down all further research is both censorship and anti-science.
It is apparent from the attacks on Kellermann's study that most
of his critics have not even read it. Simply reading the original
article in The New England Journal of Medicine (October
7, 1993) would answer 95 percent of their objections. The study
was well-designed and is entirely valid. Like any scientific study,
it has its limitations. It does not prove that guns cause a higher
murder rate in the home, only that the two are associated for
some reason. And there are more variables that need to be explored.
But the Kellermann study is a legitimate addition to the small
but growing scientific literature on the benefits and costs of
domestic firearms.
The rest of this essay will be divided into two parts: a detailed
description of the Kellermann survey, and a rebuttal of its criticisms.
The survey
Kellermann chose to conduct this survey using the "case-control
method" (or CCM). This method examines the differences between
two groups: one that possesses a certain trait, and another that
does not. For instance, a researcher may compare a "case
group" that has lung cancer to a "control group"
that is free of the disease. After asking them questions about
their behavior and environment, he may learn that the case group
generally smokes, but the control group does not. Conclusion:
smoking is correlated to lung cancer. In this instance, the arrow
of causality is easy to determine, because it is unlikely that
lung cancer causes people to start smoking. But sometimes the
arrow of causality is more difficult to determine, as in the case
of gun ownership and murder.
Kellermann's team identified 388 victims ("case subjects")
who were killed in private homes. Surviving members of the household
("proxies") formed the case group which answered the
survey. The researchers also gave an identical survey to a control
group of 388 other people, who were matched to the victims by
age, race, sex and neighborhood.
The homicides which were studied came from three metropolitan
areas. The first two were Shelby County, Tennessee (which includes
Memphis), and King County, Washington (which includes Seattle),
both from August 1987 to August 1992. The third was Cuyahoga County,
Ohio (which includes Cleveland), from January 1990 to August 1992.
King County is predominately white and enjoys a relatively high
standard of living. Cuyahoga County is 25 percent African-American,
as is 44 percent of Shelby County. The poverty levels of these
counties were 5, 11 and 15 percent, respectively. (The national
poverty rate in 1992 was 15 percent.)
The team originally identified 444 cases of homicide in the home,
about a fourth of the total number of homicides for those counties.
This number was reduced to 420 for the study for various reasons,
then to 405 because a control couldn't be found, and then to 388
because a proxy couldn't be interviewed. The high response rate
of case proxies (92.6 percent) and matching controls (80.6 percent)
is typically considered to have minimized nonresponse bias.
The survey asked 31 questions about the subjects' environment
and behavior. The results are listed below. The first two columns
reflect the percentage of those who answered yes to the question.
The third column reflects the crude odds that a murder would be
more likely for those who answered yes. For example, for the first
question, murder was 2.4 times more likely in a household where
any member drank alcohol. An odds ratio of 1.0 represents no extra
risk. Keep in mind that the crude odds are confounded by other
variables, and by themselves do not tell the whole story. Another
analytical step is needed to arrive closer to the truth.
Case Control Crude odds
Behavioral factors Subjects Subjects Ratio
---------------------------------------------------------
Any household member drank 73.3% 55.9% 2.4
alcoholic beverages
Case subject or control drank 62.8 41.9 2.6
alcoholic beverages
Drinking caused problems 24.8 5.7 7.0
in the household
Any household member had 9.0 0.8 10.7
trouble at work because
of drinking
Case subject or control had 5.5 0.3 20.0
at work because of
drinking
Any household member 11.4 2.3 9.8
hospitalized because of
drinking
Case subject or control 7.6 0.5 14.0
hospitalized because of
drinking
Any household member used 31.3 6.0 9.0
illicit drugs
Case subject or control 20.3 4.2 6.8
used illicit drugs
Any physical fights in the 25.3 3.4 8.9
home during drinking
Any household member hit or 31.8 5.7 7.9
hurt in a fight in the
home
Any family member required 17.3 2.1 10.2
medical attention because
of a fight in the home
Any adult household member 29.9 18.8 2.1
involved in a physical
fight outside the home
Any household member arrested 52.7 23.4 4.2
Case subject or control 36.0 15.7 3.5
arrested
Environmental Factors
Home Rented 70.4 47.6 5.9
Public Housing 11.1 9.8 1.5
Case subject or control 26.8 11.9 3.4
lived alone
Deadbolt locks 68.8 75.3 0.8
Window bars 19.2 20.9 0.8
Metal Security Door 25.4 26.8 0.9
Burglar alarm 7.1 11.1 0.6
Controlled security access 13.9 9.8 2.3
to residence
Dog or dogs in home 24.2 22.4 1.1
Gun or guns in home 45.4 35.8 1.6
Handgun 35.7 23.3 1.9
Shotgun 13.6 16.8 0.7
Rifle 12.2 13.9 0.8
Any gun kept unlocked 29.6 17.8 2.1
Any gun kept loaded 26.7 12.5 2.7
Guns kept primarily for 32.6 22.2 1.7
self-defense
The above chart is an example of "univariate analysis,"
or a straight comparison between the two groups. But this analysis
is incomplete. There are many variables that simultaneously contribute
to the odds of a person being murdered: drug use, domestic violence,
criminal history, level of protection, etc. A person who answers
yes to the question "Does anyone in the house use illicit
drugs?" might be nine times more likely to be murdered, but
that doesn't eliminate all the other variables that also contribute
to the total murder risk. To isolate the risk attributed to drug
use alone, researchers need to perform "multivariate analysis,"
which zeroes out all these other factors. That way, we can learn
how drug use in and of itself raises the murder risk.
Kellermann's team found only six variables that were strong enough
to be included in the final model. They found that the following
variables were associated with the following increased murder
risks:
Murder risk,
Variable Odds adjusted ratio
---------------------------------------------------
Illicit drug use 5.7 times
Being a renter 4.4
Household member hit or
hurt in a fight in the home 4.4
Living alone 3.7
Guns in the house 2.7
Household member arrested 2.5
If there were a protective benefit to having a gun in the home,
this survey would have found it. After all, if the survey could
detect an increased murder risk from the presence of a
gun in the home, there's no reason it couldn't from the absence
of one as well. But the team found no protective benefits of a
gun in the home whatsoever, for any of the subgroups studied.
Of all the methods of murder, guns were responsible for 49.8 percent
of the victims killed at home. In homes that kept a gun, the overall
murder risk was 2.7 times greater, but for gun homicides it was
4.8, while for non-gun homicides it was 1.2. Notice that 1.2 is
not significantly different from 1, so there was no increased
risk for non-gun homicides. In other words, people who kept a
gun in the home were at higher risk for gun homicides only,
not any other type of homicide. This is an important point, because
it strongly suggests that gun availability tends to turn ordinary
family arguments into something fatal, rather than the murder
victims knew they were at risk and armed themselves with a gun.
Alcohol was not included in the multivariate analysis, despite
its strong association in the univariate analysis, because alcohol
was also related to all the other variables in the final model.
Including alcohol in the final model did not substantially alter
the results. Furthermore, the odds-adjusted ratio of alcohol was
not significantly greater than 1.
The researchers also conducted a stratified analysis of their
final model, which found that the link between guns and homicide
existed in all 14 subgroups studied. This included women as well
as men, whites as well as blacks, and the old as well as the young.
Most tellingly, they found the strongest association between guns
and homicide among family members and intimate acquaintances (7.8
times more likely). Guns were much less associated to homicides
by acquaintances, unidentified intruders, or strangers (1.8 times).
Again, this supports the interpretation that guns allow family
fights to turn deadly. Here is a complete list of the murder risk
by subgroup:
Murder risk,
Subgroup Adjusted odds ratio
---------------------------------------------
Sex
Female 3.6 times
Male 2.3
Race
White 2.7
Black 2.9
Age
15-40 3.4
Over 40 2.3
Suspect related to or
intimate with victim:
Yes 7.8
No 1.8
Evidence of forced entry
Yes 2.5
No 2.8
Victim resisted assailant
Yes 3.0
No 3.1
Method of homicide
Firearm 4.8
Other 1.2
Also revealing are the circumstances surrounding the 420 homicides:
Characteristic Percent of victims
---------------------------------------------------
Scene
Inside residence 88.8%
Within immediate property 11.2
Sex of victim
Female 36.9
Male 63.1
Race or ethnic group of victim
White 33.3
Black 61.9
Native American, Eskimo, Aleut 1.0
Asian or Pacific Islander 1.7
Other 2.1
Age of victim (years)
15-24 13.8
25-40 40.7
41-60 25.2
Over 61 20.2
Circumstances
Altercation or quarrel 44.0
Romantic triangle 6.9
Murder-suicide 4.5
Felony-related 21.9
Drug-dealing 7.6
Homicide only 13.3
Other 1.7
Relationship of offender to victim
Spouse 16.7
Intimate acquaintance 13.8
First-degree relative 9.5
Other relative 2.9
Roommate 2.9
Friend or acquaintance 31.0
Police officer 1.0
Stranger 3.6
Unknown (unidentified suspect) 17.4
Other 1.4
Method of homicide
Handgun 42.9
Rifle 2.4
Shotgun 3.6
Unknown firearm 1.0
Knife or sharp instrument 26.4
Blunt instrument 11.7
Strangulation or suffocation 6.4
Burns, smoke, scalding 2.4
Other 3.3
Victim resisted assailant
Yes 43.8
No 33.3
Not noted 22.9
Evidence of forced entry
Yes 14.0
No 84.3
Not noted 1.7
Legally excusable homicide
Yes 3.6
No 96.4
Several points about this chart are noteworthy. The first is that
at least 76.7 percent of the murderers were relatives, friends
or acquaintances of the victim. In fact, the victim's murderer
was 21 times more likely to be a relative or acquaintance than
a stranger. Even in the 14 percent of the cases involving forced
entry, the vast majority of the intruders were known to the victim.
The threat of forced entry is the most commonly cited reason for
possessing a domestic firearm, but the researchers found no protective
benefit for this subgroup either.
The researchers write: "Efforts to increase home security
have largely focused on preventing unwanted entry, but the greatest
threat to the lives of household members appears to come from
within."
Of the 388 homicides surveyed, 21 victims died while unsuccessfully
trying to defend themselves with a gun. Only 15 of the deaths
were ruled justifiable homicide or legal self-defense, and four
of these were by the police.
The authors did present their study with several limitations.
First, they acknowledged that they limited their study of homicides
to those which occurred in the home, their goal simply being to
measure the effectiveness of gun protection in the home. Homicides
at other locations (such as bars, work or the streets) were not
counted. Therefore, the dynamics of homicide in these locations
might be quite different.
Second, they acknowledged that their research was conducted in
urban settings that lacked a substantial Hispanic population.
The dynamics of homicide in that community therefore might be
quite different.
Third, they acknowledged that the arrow of causality could point
in the opposite direction in some of the cases. For example, a
person might acquire a gun in response to a specific threat. If
the threat was then carried out, the correlation between the gun
and the murder could be partly attributed to the failure of the
weapon to provide protection.
Fourth, they acknowledged that a third, unidentified factor might
be responsible for both gun possession and murder risk.
For example, the victims may have had violent, aggressive personalities
or some other psychological disorder that predisposed them to
both greater gun possession and murder. The authors note that
they included several behavioral markers for aggression and violence
in their survey, but they did not conduct a full "psychological
autopsy" given the impractical nature of such a task. Still,
they note that "a link between gun ownership and any psychological
tendency toward violence or victimization would have to be extremely
strong to account for an adjusted odds ratio of 2.7."
So, what are the study's conclusions? The authors write:
"Despite the widely held belief that guns are effective for
protection, our results suggest that they actually pose a substantial
threat to members of the household. People who keep guns in their
homes appear to be at greater risk of homicide at the hands of
a family member or intimate acquaintance. We did not find evidence
of a protective effect of keeping a gun in the home, even in the
small subgroup of cases that involved forced entry."
It is important to note that Kellermann's findings agree with
many other studies. For example, the FBI reports that in 1993,
only 1.7 percent of all handgun murders were justifiable homicides.
Kellermann's team found that only 3.6 percent of the 420 homicides
it studied were justifiable. The FBI found 19.1 percent of all
homicides to be felony-related; Kellermann found 21.9 percent
of those in the home to be felony-related. In 1994, the FBI found
that only 13 percent of all murder victims were killed by strangers.
Kellermann found that 3.6 percent of the domestic homicides were
strangers and 17.4 percent were never identified. The FBI found
that 12 percent of all killers in 1994 were related to the victim;
Kellermann found this figure to be 12.4 percent in domestic homicides.
(2)
Kellermann's research also confirms numerous studies like the
one done by Linda Saltzman, which found that assaults by family
members or intimate acquaintances are far more fatal when the
weapon is a gun. (3) There are also many cohort and interrupted
time-series studies that demonstrate a strong link between gun
availability and homicide rates in the community. (4) Kellermann's
study has now confirmed this correlation at the individual household
level as well.
Criticisms of the study
Pro-gun advocates have raised a number of objections to this
survey. The following are actual arguments taken from the Internet
and the NRA: (5)
1. "99.8 percent of the protective uses of guns do not
involve homicides," says Paul Blackman of the NRA. Defensive
gun uses include waving the weapon, firing warning shots, wounding
the intruder, etc.
It is simply untrue that researchers cannot measure the nonfatal
protective benefits of firearms, or that Kellermann's survey failed
to detect such a benefit. If firearms deter, scare away or wound
intruders, then the murder victimization rate of gun owners should
be lower than non-gun owners. The absence of a gun in the
home would have been recognized as a murder risk, rather than
the presence of a gun.
Kellermann's case-control method was ideally suited to detect
such benefits, if they existed. For example, suppose that guns
save 100,000 lives a year, through nonfatal means. Assuming a
perfect protection rate, we would see no homicides in households
with guns, and 100,000 in households without them. A case-control
survey would find the risk associated with guns to be 0.0 -- a
perfect benefit. But suppose (more realistically) that guns protect
their owners only half the time. There might then be, say, 100,000
homicides in homes with guns and 200,000 in homes without them.
A researcher using the case-control method would find that 33
percent of the cases and 50 percent of the controls owned guns,
for an odds ratio of .50. Being less than 1, that's a very strong
benefit.
Of course, Kellermann's survey found quite the opposite -- a risk
2.7 times greater.
2. Guns do not emit magic rays that control people's minds,
or magnetize murderers to the doorstep.
This strawman argument is based on a false stereotype. Over 76
percent of the homicides were committed by a relative or acquaintance
of the victim, and only 3.6 percent were verified as strangers
breaking in. Furthermore, arguments and romantic triangles comprised
half the homicides. But the most important point here is that
a gun in the home only raised the risk of gun homicide
-- not homicide by any other means. The most straightforward explanation
is that greater gun availability transformed a normal family fight
into something much more deadly.
3. People threatened by violence bought guns to defend themselves,
hence the correlation between gun ownership and murder.
This is possible, but the number would only be very small,
for the following reasons. The study already controlled for domestic
violence, so the only way this could happen is if the murderer
threatened the life of the victim before things escalated into
violence. The victim would then have to buy a gun, which would
fail to protect.
Several things make this unlikely. First, we would expect a history
of violence to precede any threats or attempts on a person's life,
which is, after all, the ultimate form of violence. Second, the
study showed that gun ownership resulted in an increased risk
in gun homicides only, not any other type of homicides.
Why would the murderer restrict himself to a gun, and then only
if the victim had a gun? Third, this makes a poor case for gun
deterrence, since the correlation is only possible when the gun
fails to protect. Again, the researchers found no protective benefits
of gun ownership.
4. Kellermann's study didn't document whether a firearm used
in a particular homicide was the same one kept in the home, or
whether it might have been carried in by the murderer.
True, the study doesn't say, but the study's findings make
it logically impossible for a significant number of these guns
to have been brought in from the outside. The study found that
keeping a gun in the house raised the chances of gun homicide
only, not any other kind of homicide. It also found that it raised
the chances of being killed by a family member or intimate acquaintance,
not a stranger or non-intimate acquaintance. We can therefore
eliminate the possibility that owning a gun raises the risk of
a stranger breaking in (and then only with a gun!). The only alternative
is that a family member or intimate acquaintance brought a second
gun into the house on the day of the murder (any longer-term storage
would have classified it as a "gun in the house"). That
all murderers using handguns would do this seems highly implausible.
It is also unlikely that these live-in murderers would restrict
themselves to guns; we should expect to see other murder methods
employed as well. The only plausible conclusion is that the vast
majority of the guns used for homicide were the ones kept in the
house.
Pro-gun advocates might try a different tack. If an angry spouse
has a gun, the other might seek protection by buying a gun also.
However, this strategy had to fail for the survey to find a correlation
between gun ownership and homicide. This does nothing to rescue
the pro-gunner's point that guns protect their owners.
5. Proxies for the murder victim were not asked if the gun
had previously been used for self-defense.
What this objection is asking us to imagine is this: a gun
prevents a murder from happening in, say, nine cases. But on the
tenth it fails (by necessity, to produce the murder victim in
question). If guns really provided this kind of protection, we
could easily imagine that one of the previous nine murder attempts
would have been successful, had the victim not possessed a gun.
In that case, non-gun owners would have seen a higher murder rate.
This is something the study would have found (see point 1), but
it did not; it found a higher murder rate among gun owners. Pro-gunners
might then argue that an individual facing a likely threat sought
protection by buying a gun, hence the higher correlation. But
this is the same argument rebutted in point 3. Ultimately, the
pro-gunners starting assumption is incorrect. Guns do not prevent
a series of threats, one of which ultimately succeeds; rather,
guns enhance the possibility of murder.
6. "These people were highly susceptible to homicide,"
says Paul Blackman of the NRA. "We know that because they
were killed."
If there is an Illogic Hall of Shame, this remark deserves to
be emblazoned above its front entrance. By this reasoning, we
should not put seat belts in cars, because people killed in car
crashes were susceptible to those accidents anyway.
What Blackman is doing here is evoking a general risk for murder,
while ignoring its specific risk multipliers. You may, in general,
have an antagonistic person in your life given to flashes of murderous
temper. But there are specific factors that may increase the risk
of murder. Does he drink? Use drugs? Commit crime? Own a gun?
Increasing any of these behaviors increases the risk. But it makes
no sense to increase the risk multiplier, let someone get murdered,
and then argue that the multiplier was not at fault, since the
victim was obviously susceptible to murder anyway.
This argument also ignores one of the study's findings, that a
gun in the home increased the risk of gun homicide only, and not
any other method of homicide.
7. Of course if someone gets shot in their home, there's bound
to be a gun in the home. And drowning victims are always found
near water.
This is a variation of the Blackman argument above. Water is not
the only thing correlated with drowning. There are all the usual
risk multipliers, such as a lack of lifeguards, life jackets,
warning signs, adult supervision, etc. And notice that this analogy
is incorrect. The analogy of guns isn't to water; it's to a lack
of lifeguards. The analogy to water is actually murder in general.
8. The majority of the homicides were not committed by guns,
so could not have been committed by Kellermann's scary "guns
in the home."
Homes that kept guns experienced an increase in homicides, but
this increase was entirely due to gun-related homicides, not homicides
by any other method. This objection misses the point.
9. The researchers did not include in their analysis those
cases where the home-owner shot a non-resident intruder.
These cases were rare, but even so, this objection is irrelevant.
The protective benefits of a gun would have still shown up in
the different victimization rates of gun-owning and gun-less households.
(See point 1.)
10. This study was conducted by medical doctors who were out
of their league; this is an issue best left for criminologists.
Epidemiologists are highly experienced at using the case-control
method to determine risk factors. This is how cigarette smoking
was linked to lung cancer, for example. The statistical method
is the same no matter what the risk factor, be it cigarettes,
a virus, a missing vitamin or a gun. A good analogy is that of
an astronomer using optics technology to make a breakthrough in
optometry.
11. The use of the case-control method allows for spurious
associations.
This objection is bogus, since it ignores the role of multivariate
analysis.
12. A disproportionate number of survey respondents were criminals,
hence the correlation between gun ownership and murder.
But the survey controlled for criminal backgrounds and domestic
violence. The gun/murder correlation was reached after multivariate
analysis factored these variables out.
13. The study was conducted in urban areas, which have high
crime. This would promote both gun ownership and death in violent
crimes.
But the survey controlled for neighborhoods. The researchers matched
the control subjects by neighborhood to the case subjects.
14. Most of the victims were black, and blacks have a higher
murder rate.
Irrelevant. The study controlled for race.
15. The victims typically had stunningly different lifestyles
from the controls: more drinking, crime, drug use, domestic violence,
etc.
Again, this objection ignores that multivariate analysis factored
out all these variables. The "2.7 times" statistic measures
gun possession alone (within the limits of the study's
31 variables).
16. The survey failed to ask about other variables.
The survey asked questions about 31 variables, but in a complex
world it's always possible to think up more. Kellermann asked
about the most obvious ones; even then, only six retained significance
in the final analysis. If there were indeed a "missing variable,"
it would have to be extremely strong -- and probably extremely
obvious as well -- to produce a murder risk of 2.7.
17. The survey failed to determine the strength of the variables
(severity of drug use, domestic violence, crime, etc.)
Indeed, the study asked only "yes or no" questions about
problems in the home. For example, it asked whether any member
of the household had been arrested, without determining the severity
of the criminal charge. However, just because the individual questions
did not control for severity does not mean the entire study didn't,
since it asked a total of 15 questions about behavior, many closely
related to each other. But this is really an argument about refining
the study's results, not overturning its conclusions, which would
be highly unlikely.
18. The study underestimated the amount of drug use or other
domestic problems, which was really the cause of an increased
murder risk for gun owners.
Not true. After the researchers controlled for these other risks,
the murder risk associated with guns increased, from 1.6
in the univariate analysis to 2.7 in the multivariate analysis.
If the study had underestimated the amount of drug use or other
domestic problems, then the true risk associated with guns would
be even greater.
19. The number of guns in the control homes were underreported.
If this were true, this would indeed artificially raise the murder
risk of having a gun in the home. Conversely, if the number of
guns in the case homes were underreported, then this would
artificially lower the murder risk associated with guns.
But the authors do not believe this was a problem. First, in two
of the three counties they studied, they compared their survey
results to a pilot study of homes listed as the addresses of owners
of registered handguns. The survey respondents' answers were found
to be generally valid. Second, the rate of gun ownership by the
control respondents in all three counties was comparable to estimates
derived by previous social surveys and Cook's gun-prevalence index.
(6)
Of course, respondents might not have disclosed possession of
illegal guns. Pro-gunners argue that the case subjects
were prevented from underreporting the possession of such guns,
because murder itself is almost impossible to underreport. (It's
difficult to hide either a corpse or a person's absence). And
a murder causes the police to search -- and usually find -- the
murder weapon, so the truth about gun ownership in the case homes
probably came out. However, control subjects have not been investigated
by the police for guns, nor do they desire such a search, so they
may lie about possessing an illegal gun. The researchers were
aware of this possibility, and they assured the respondents that
their answers were confidential, and that they could freely refuse
to answer any questions. Even so, only a very few respondents
refused to answer a question. Ultimately, the possibility of underreporting
remains pure speculation at the moment, and further research needs
to clarify this question.
Conclusion
The Kellermann study is valid, if incomplete -- as any study
must necessarily be. More research needs to be done on other possible
variables contributing to the murder rate, although Kellermann
has apparently identified the most important ones. The results
could be refined by determining the severity of some factors,
like criminal background. And it would be good to reconfirm the
honesty of the respondents' answers. But the study itself is sound,
and gun-control advocates can use it with confidence.
Return to Overview
Endnotes:
1. Arthur Kellermann et. al., "Gun Ownership as a Risk
Factor for Homicide in the Home," The New England Journal
of Medicine, October 7, 1993, pp. 1084-1091.
2. Federal Bureau of Investigations, Crime in the United States,
annual.
3. Linda Saltzman, et. al., "Weapon Involvement and Injury
Outcomes in Family and Intimate Assaults," Journal of
the American Medical Association, 1992;267, pp. 3043-7.
4. A.J. Reiss, Jr. and J.A. Roth, eds., Understanding and Preventing
Violence: Panel on the Understanding and Control of Violent Behavior
(Washington D.C.: National Academy Press, 1993), pp. 42-97; P.J.
Cook, "The Effect of Gun Availability on Robbery and Robber
Murder: A Cross Section Study of Fifty Cities," Policy
Stud Rev Annu 1979;3, pp. 743-81; J.H. Sloan, A.L. Kellermann,
D.T. Reay, et. al., "Handgun Regulations, Crime, Assaults,
and Homicide: a Tale of Two Cities," New England Journal
of Medicine, 1988;319, pp. 1256-62; C. Loftin, et. al., "Effects
of Restrictive Licensing of Handguns on Homicide and Suicide in
the District of Columbia," New England Journal of Medicine,
1991;325, pp. 1615-20.
5. I am deeply indebted to Tim Lambert of the University of New
South Wales for providing many of these objections and rebuttals,
which came from his archived postings to the Internet newsgroup
talk.politics.guns. Many of the responses here are based
on his answers.
6. J.D. Wright, P. Rossi, K. Daly, E. Weber-Burdin, "Weapons,
crime and violence in America: a literature review and research
agenda," (Washington, D.C.: Government Printing Office, 1983),
pp. 212-60, 361-411; P.J. Cook, "The effect of gun availability
on robbery and robber murder: a cross section study of fifty cities,"
Policy Stud Rev Annu 1979; 3, pp. 743-81.