Myth #6a - "What about the University of Maryland study?"

Myth #6a - "What about the University of Maryland study?"

A recently published study by the University of Maryland's Violence Research Group, claimed that average monthly homicides by gun increased in four of five urban areas studied, after the adoption of liberalized concealed carry reform laws. This statistical "factoid" was first offered up March 13, 1995 by the Associated "Black Rhino" Press, and was widely reported (and misreported) elsewhere. However, the researchers do not attempt to argue that any of these gun-related homicides were committed by concealed carry permit holders, nor do they consider the relative proportion of concealed carry permit holders in each of the studied localities, which if one were to assume that less restrictive concealed carry is associated with increased homicide, would be a particularly important factor to consider. Information that is available from other sources, such as the state government in Florida, suggests that criminality by concealed carry permit holders is virtually unknown. If increased carry by citizens with CCW permits is responsible for any increased homicide, the researchers do not establish a plausible explanation for the change in rate, if such a change actually exists. Also the researchers selected the cities they did on the basis of their status as "large urban areas," rather than looking at the homicide rates for each state as a whole, when the concealed-carry laws were enacted statewide.

Three of the five localities studied were in Florida (where a statewide CCW reform law was enacted in 1987, and where "gun control" advocates predicted increased violent crime would make it into the "Gunshine State"). Both in Jacksonville, where the study claims that the monthly average number of gun-related homicides increased by 74 percent, and in Tampa, where the study claims the monthly average number of gun-related homicides jumped 22 percent, the study notes that the rates of homicide without firearms also increased. In Miami, a city of intermediate size relative to Tampa and Jacksonville, the study claims gun-related homicides per month increased 3 percent, but this analysis is based upon a different time span than that for Tampa and Jacksonville. The researchers claim that using a different baseline was necessary "because of an unusually sharp increase in homicide rates [in Miami] in May 1980 after an influx of Cuban refugees." Results of time series analyses such as this, and the similar study of the effects of Washington D.C.'s gun registration law by the same researchers, are highly dependent upon the time spans chosen for study. In those Florida cities for which the most dramatic results were obtained, the baseline used stretched all the way back to 1973, but for Miami, the baseline began in 1983. Presumably, given the higher initial Miami homicide rates that the researchers attribute to the Cuban refugees, starting off with same baseline year for Miami as for the other Florida cities would have produced a resulting increase less than the 3 percent observed.

Complicating any analysis of Florida's crime rates is the fact that almost immediately following the passage of Florida's 1987 CCW reforms, the state changed the manner in which it collects crime statistics, so comparisons before and after the implementation of the law can be invalid on that basis. However, the number of homicides ought not to be affected by that, since to have a homicide, you need to have a body. Statistical changes ought not to affect the ability to count bodies, which is essentially what the Maryland study does (albeit very crudely, and without distinguishing between justifiable homicides and murders). The researchers cite FBI's Uniform Crime Reports data in asserting that justifiable homicides are uncommon, but the FBI numbers actually undercount the number of justifiable homicides by civilians, since FBI statistics rely upon the initial determination made about an incident. A statewide analysis of the Florida data, reveals that the U. Maryland researchers missed the overall downward trend in murder/manslaughter rates since the Florida concealed-carry law was enacted.

The question of the direction of causality's arrow is critically important to consider. Does increased homicide lead to more people obtaining permits to carry, or does increasing the availability of permits to carry increase the homicide rate? The Maryland study's researchers seem to want to argue the latter, but they have thus far offered no evidence that CCW permit holders are doing the killing! The sampling of these particular localities, since nonrandom, can also be used to introduce bias into such a study, and sociological differences between localities also need to be controlled for.

The wide disparities in the with-gun homicide rates given in the study seem very unusual at first glance, and this is the result of the fact that the study is calculating its percent increases in absolute terms (4 going up to 7) rather than per 100,000 population, as is necessary for any realistic assessment. The attempt by the researchers to control for population changes by lumping together data from all five studied cities is a less than adequate solution if they intend to consider the homicide rates seperately for each city elsewhere in their report (and in their quotes to the press). The researchers themselves admit that "[t]he population of all five areas grew over the study period, especially in the Florida cities. Homicide counts thus may have changed after the laws in part because of increases in the populations at risk."

The two other localities examined were Jackson, Mississippi, where the average monthly gun-related homicide rate increased by 43 percent; and Portland, Oregon, where the average monthly gun-related homicide rate_fell_by 12 percent. The Portland data, the researchers note, did not provide enough homicides, so data from two adjoining counties were included as well. (Again, one presumes that if this had not been done, the Portland rate would have been seen to decline even more than the 12 percent reported.) Calculating average numbers of homicides per month serves to make the numbers smaller, and if there are few homicides in a locality to begin with, as was apparently the case in Portland, the degree of "noise" in the data can produce some "startling" percentage changes, if considered in absolute terms. (If one average has 6 homicides, and the next, 3, that's a "50% DROP!") It's also widely known in criminology that more violent crime occurs in summer months than in winter months, so averaging over the year, as a "moving average" technique does, can also serve to produce smaller numbers, more suceptible to "startling" percentage changes. This study design (and the similar study of Washington D.C.'s gun registration law) seems geared towards maximizing "noise," rather than discerning a longer-term trend.

The researchers' conclusion is tentative: "While advocates of these relaxed [carry] laws argue that they will prevent crime, and suggest that they have reduced homicides in areas that adopted them, we strongly suggest caution. When states weaken limits on concealed weapons, they may be giving up a simple and effective method of preventing firearm deaths." This quotation also points up another aspect of bias in the study. What exactly is significant about gun related homicides, versus total homicides? Does the fact that a homicide is committed with a firearm make the slain any more dead than if the homicide was committed with a knife, or with hands and feet? The researchers claim that homicides by other means remained mostly steady, yet in the two Florida cities showing the greatest increases, both gun and non-gun related homicides went up. If the increased presence of firearms in the hands of the law-abiding serves to deter murders with other weapons, this effect would be discounted when only homicides involving firearms are considered. In the case of Florida, since the murder rates have decreased when considered on a statewide basis, these supposed increases in urban areas must have been offset by drastic drops elsewhere.

The researchers do not consider Florida data later than 1991, since they say other laws, such as the 1991 passage of waiting periods and background checks on new gun purchases in Florida, would make it difficult to disentangle the results of the new laws from the concealed carry law. Yet presuming that the declines in murder rates since 1991 are attributable to background checks and waiting periods runs counter to the assumption that gun availability is a crucial factor driving murder rates. Neither background checks nor waiting periods would have any appreciable effect on the existing supply of guns available, while concealed carry opponents claim that CCW laws make guns more available in the heat of an argument. To compare the potential effects of these laws on the availability of guns is to compare apples and oranges. Concealed carry can be the ultimate test of the "gun availability" hypothesis. So far, the awful consequences that are habitually predicted by those opposed to concealed carry reform laws haven't been shown to occur. If anything, the available data is consistent with the view that concealed carry has a deterrent effect, or at the least has no direct negative effect.

The researchers attempt to speculate that increased availability of legal concealed weapons is leading to an "arms race" between criminals and their potential victims, and more criminals are using firearms than previously. They write "[g]reater tolerance for legal carrying may increase levels of illegal carrying as well. For example, criminals have more reason to carry firearms --and to use them-- when their victims might be armed." As Daniel Polsby points out in the same journal, this "arms race" hypothesis would presumably also operate when greater numbers of armed police officers are introduced into a locality. But the legitimacy of availability of concealed carry permits to the law abiding is not predicated on the frequency of misbehavior of criminals-- except in the minds of "gun control" advocates who wish to prohibit any item that could potentially be misused by criminals (chemical defense sprays and stun guns included), regardless of its effectiveness in protecting the weak from the predations of the strong. Theirs is a policy which demands that victims "lie back and enjoy it," rather than_fight_back, and reduce their risk of injury or death.

Recommended Reading:

"Easing Concealed Firearms Laws: Effects on Homicide in Three States", McDowall, David; Wiersema, Brian; and Loftin, Colin
J. of Criminal Law and Criminology v.86, n.1, pp.195-204 (1995)

"Firearms Costs, Firearms Benefits, and the Limits of Knowledge", Polsby, Daniel
J. of Criminal Law and Criminology v.86, n.1, pp.207-220 (1995)