The Danger Of The CDC Cherry Picking Gun Use Research

posted on August 10, 2018

Gary Kleck is the David J. Bordua Professor Emeritus of Criminology at Florida State University. In 1993, his book, Point Blank: Guns and Violence in America, won the Michael J. Hindelang Award, given by the American Society of Criminology to authors that have made “the most outstanding contribution to research in criminology.” His studies of crime, self-defense and firearms were cited by the U.S. Supreme Court’s ruling in District of Columbia v. Heller.

In 1995, he and Professor Marc Gertz published the results of the most comprehensive survey undertaken on defensive uses of guns, which polled around 5,000 American households. The study concluded that Americans were using firearms to defend against criminals approximately 2.5 million times per year.

The article appeared with a preface by Marvin Wolfgang, the “Dean of American Criminology,” who described himself as “as strong a gun control advocate as can be found among the criminologists in this country.” Yet Wolfgang praised the study: “The Kleck and Gertz study impresses me for the caution the authors exercise and the elaborate nuances they examine methodologically. I do not like their conclusions that having a gun can be useful, but I cannot fault their methodology. They have tried earnestly to meet all objections in advance and have done exceedingly well.”

Recently, Kleck discovered that, shortly after his survey results were released, the Centers for Disease Control (CDC) took an interest in defensive gun uses, leading to results it buried for 20 years.

A1F: How did you discover the CDC surveys?

Kleck: I was looking for state-level data on gun ownership levels, and I knew that CDC’s surveys, the Behavioral Risk Factor Surveillance System, or BRFSS, had asked for that data and broken it down to the state level a few times. I accessed the CDC’s website and looked for the questionnaires it had used.

The BRFSS has a long list of standard questions that all states use in their surveys, and it also has optional modules that states can ask, or not ask, as they choose. I found that the CDC had three times—in 1996, 1997 and 1998—had an optional module on gun ownership that included questions on defensive gun use. Depending upon the year, four to seven states had chosen to ask these questions.

What struck me about the CDC questions was that they were very carefully worded. Some surveys have asked questions that were unduly restrictive: “Have you used a handgun in self-defense?” which would leave out uses of shoulder guns, or “Have you used a firearm to defend yourself in your home?” which would leave out defenses that occurred outside the home. CDC did not make these mistakes; their questions were very well-worded.

Once CDC saw that its own surveys implied huge numbers of defensive gun uses, it appears to have lost all interest in the subject.

It was disappointing that so few states had responded, but I could extrapolate those results to the entire nation by using the results that Marc Gertz and I had obtained in our survey. For example, if we had found in our survey that the national DGU rate was 60 percent of the rate in the set of states that asked the DFU question in the BRFSS, we could multiply the DGU rate for those states by 60 percent to roughly extrapolate what the results would have been if CDC had asked the question nationwide.

A1F: You mention in your paper that there have been 21 prior national surveys on defensive gun use. How does the CDC survey add to what you already knew?

Kleck: A lot of those surveys were not very good. For instance, some had a small sample size. The CDC has a huge sample size. Even though the optional modules on defensive gun use were only asked in four to seven states, depending upon the year, the questions were nevertheless asked of 3,200 to 4,500 persons. Also, the questions asked were very well-phrased—any defensive use of a firearm, whether it was actually fired or not, whether it was used in the home or not, but excluding uses in military service or law enforcement. They were really carefully worded.

A1F: Do the CDC results confirm the results of prior studies?

Kleck: The best prior national studies have concluded that there are about 1 to 3 million defensive gun uses per year. The CDC results, adjusted and extrapolated to the entire country, indicate from 600,000 to 1.9 million defensive uses of a gun per year. This probably reflects that violent crime, and thus the need to defend against it, dropped steeply during the 1990s, and the CDC surveys were fielded in the late 1990s.

There is also one factor that I could not adjust for: The people surveyed may have been reluctant to admit defensive gun uses to the CDC. We know that many gun owners are reluctant to admit gun ownership to a telephone pollster. In states that have firearm registration or, like Illinois, require gun owners to obtain a state identification card, polls have been taken of persons who are known gun owners and up to 12 percent of them deny that they own guns. And that is of people whose ownership is legal, and who know that the government already knows about it!

Also, the NRA over this period was criticizing CDC for funding only studies that supported gun control. To the extent that gun owners knew that, it might have made some of them unwilling to tell CDC about defensive gun uses. It wouldn’t be something they’d want to tell a government agency that they suspected was opposed to gun ownership. The actual number of defensive gun uses might thus be higher than what cdc found, but I couldn’t adjust for that.

A1F: Was there anything interesting about the timing of the CDC studies?

Kleck: The CDC had shown no interest in estimating the frequency of defensive gun uses prior to 1996. Marc Gertz and I conducted our DGU survey in spring of 1993, and found there were about 2.5 million annual defensive uses of guns. We announced that at an academic conference in 1994, and published it in an academic journal in 1995. There are individuals in my field who react to any research results they don’t like by ignoring them, so I had Florida State University send out a press release on our results. This generated a huge amount of publicity and made it impossible to ignore the results.

Suddenly the CDC took an interest in defensive gun uses. The National Institute of Justice also sponsored its own survey, and got results almost exactly the same as our own. Once CDC saw that its own surveys implied huge numbers of defensive gun uses, it appears to have lost all interest in the subject. After 1998, it didn’t even make questions about defensive gun use part of an optional module.

A1F: How relevant is this to the debate over gun ownership?

We have 1 to 3 million defensive gun uses per year. And there are around 600,000 gun-related crimes annually, including cases where the criminal didn’t actually use a gun, but the victim reported the criminal possessed one during the offense. Even by that generous standard, defensive gun uses far outnumber criminal gun uses. The results do not imply anything about the merits of gun control measures that would not disarm noncriminals who might become crime victims, since such measures would not significantly reduce DGU by noncriminals. On the other hand, high estimates of DGU frequency are very relevant to prohibitionist controls that would deny guns to noncriminals as well as criminals, since these kinds of controls would reduce the injury-reducing benefits that accrue from large numbers of crime victims using guns for self-protection.

David T. Hardy is a Tucson, Ariz., firearm attorney and Second Amendment author who wrote the book, I’m from the Government, and I’m Here to Kill You: The Human Cost of Official Negligence. It’s available on Amazon.


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