Guns Save Lives

That Time The CDC Asked About Defensive Gun Uses

Paul HsiehContributor 

Healthcare

I cover health care and economics from a free-market perspective.

Last month, I discussed the need for more robust and intellectually balanced research into gun use in the United States. In particular, I proposed that “Any Study Of ‘Gun Violence’ Should Include How Guns Save Lives.”

In particular, a 2013 study ordered by the Centers for Disease Control and Prevention (CDC) and conducted by The National Academies’ Institute of Medicine and National Research Council reported that, “Defensive use of guns by crime victims is a common occurrence”:

Almost all national survey estimates indicate that defensive gun uses by victims are at least as common as offensive uses by criminals, with estimates of annual uses ranging from about 500,000 to more than 3 million, in the context of about 300,000 violent crimes involving firearms in 2008.

Subsequently, I learned of a recent paper by Florida State University professor Gary Kleck, “What Do CDC’s Surveys Say About the Frequency of Defensive Gun Uses?“

Kleck looked at some previously unpublished results from the CDC surveys conducted in the 1990s and concluded:

Today In: Opinion

In 1996, 1997, and 1998, the Centers for Disease Control and Prevention (CDC) conducted large-scale surveys asking about defensive gun use (DGU) in four to six states. Analysis of the raw data allows the estimation of the prevalence of DGU for those areas. Estimates based on CDC’s surveys confirm estimates for the same sets of states based on data from the 1993 National Self-Defense Survey (Kleck and Gertz 1995). Extrapolated to the U.S. as a whole CDC’s survey data imply that defensive uses of guns by crime victims are far more common than offensive uses by criminals. CDC has never reported these results.

Subsequently, Kleck removed this version of the paper, although a copy of the original can be found here. As reported by Reason editor Brian Doherty:

PROMOTED

You will note the original link doesn’t work right now. It was pointed out to me by Robert VerBruggen of National Review that Kleck treats the CDC’s surveys discussed in this paper as if they were national in scope, as Kleck’s original survey was, but they apparently were not. From VerBruggen’s own looks at CDC’s raw data, it seems that over the course of the three years, the following 15 states were surveyed: Alaska, Colorado, Hawaii, Kentucky, Louisiana, Maryland, Mississippi, Montana, Ohio, New Hampshire, New Jersey, New York, North Dakota, Pennsylvania, and West Virginia. (Those states, from 2000 census data, contained around 27 percent of the U.S. population.) Informed of this, Kleck says he will recalculate the degree to which CDC’s survey work indeed matches or corroborates his, and we will publish a discussion of those fresh results when they come in. But for now Kleck has pulled the original paper from the web pending his rethinking the data and his conclusions.

Furthermore, economist Alex Tabarrok has noted an interesting issue of statistics in his blog post, “Defensive Gun Use and the Difficult Statistics of Rare Events“:

People answering surveys can be mistaken and some lie and the reasons go both ways. Some people might be unwilling to answer because a defensive gun use might have been illegal (Would these people refuse to answer?). On the other hand, mischievous responders might report a defensive gun use just because that makes them sound cool.

The deep problem, however, is not miscodings per se but that miscodings of rare events are likely to be asymmetric. Since defensive gun use is relatively uncommon under any reasonable scenario there are many more opportunities to miscode in a way that inflates defensive gun use than there are ways to miscode in a way that deflates defensive gun use...

The bottom line is that it’s good to know that the original Kleck and Gertz survey replicated — approximately 1% of adult Americans did report a defensive gun use in the 1990s — but the real issue is the interpretation of the survey and for that a replication doesn’t help.

So what can Americans interested in rational gun policy make of this?

My own preliminary conclusions:

1) We still don’t really know how many defensive gun uses (DGUs) there are each year.

Doherty offers his own analysis of reasons why reported numbers might be both too low or too high in his 2015 article, “How to Count the Defensive Use of Guns.”

2) The number of DGUs has likely increased since the 1990s.

The numbers of Americans with legal concealed weapons permits has increased dramatically from the 1990s to today, as more states have adopted laws allowing such permits. It would make sense that the numbers of DGUs has likely increased as well.

CDC′s “Tom Harkin Global Communications Center” located on the organization′s Roybal Campus in... [+]

 (PUBLIC DOMAIN IMAGE, COURTESY WIKIPEDIA.)

3) We don’t know why the CDC chose not to publish that data from the 1990s.

Kleck offers some ideas in his original paper. One possible explanation:

Another factor, however, might also have played a role in the decision of CDC personnel to not report the DGU findings. For CDC’s own surveys to generate high estimates of DGU prevalence was clearly not helpful to efforts to enact stricter controls over firearms, since it implies that some such measures might disarm people who otherwise would have been able to use a gun for self-protection.

One CDC official in the 1990s openly told the Washington Post that his goal was to create a public perception of gun ownership as something “dirty, deadly — and banned.” Given that history, I can’t dismiss Kleck’s critique.

4) The right to self-defense does not depend on statistics (echoing a point I made last month).

I especially like Doherty’s discussion on this:

However interesting attempts to estimate the inherently uncountable social phenomenon of innocent DGUs (while remembering that defensive gun use generally does not mean defensive gun firing, indeed it likely only means that less than a quarter of the time), when it comes to public policy, no individual’s right to armed self-defense should be up for grabs merely because a social scientist isn’t convinced a satisfyingly large enough number of other Americans have defended themselves with a gun.

In summary, the topics of “gun violence” and defensive gun uses are still topics worthy of objective scientific research. And again, any study of ‘gun violence’ should include how guns save lives.