A Second Look at a Controversial Study About Defensive Gun Use

Criminologist Gary Kleck revises his paper on the incidence of the use of firearms for self-protection.

In April, criminologist Gary Kleck reported that he had uncovered evidence supporting his contention that Americans use firearms in self defense over 2 million a times a year. The survey he discovered had not been previously analyzed, but he reported that it matched what he found in the 1993 survey he conducted with Marc Gertz and published in 1995, known as the National Self-Defense Survey (NSDS).

His new report was based on surveys conducted by the Centers for Disease Control (CDC) in its Behavioral Risk Factor Surveillance System (BRFSS) survey in the years 1996-98. This finding was touted by many outlets—including Reason—as evidence in support of the utility of private gun ownership.

Shortly after that study was released, however, Robert VerBruggen of National Review (who has been of inestimable help in thinking through these issues) tweeted that he noticed, by studying the raw survey data himself, that Kleck had mistaken what were in fact surveys limited to small numbers of states per year for a national survey, analogous to Kleck/Gertz’s own national surveys.

in direct response to queries from Reason, who first directly notified Kleck of his error, he worked through and has since issued a revised version of the paper, published as was the original as a working paper on the Social Science Research Network. In the new version, Kleck re-analyzes the BRFSS survey data accurately as limited to a small number of states, and ultimately concludes, when their surveys are analyzed in conjunction with his NSDS, that their surveys indicate likely over 1 million defensive uses of guns (DGUs) a year nationally, compared to the over 2 million of his own NSDS.

Here’s how Kleck got to that new conclusion. The BRFSS, as Kleck describes it in his paper, “are high-quality telephone surveys of very large probability samples of U.S. adults…even just the subset of four to seven state surveys that asked about DGU in 1996-1998 interviewed 3,197-4,500 adults, depending on the year. This is more people than were asked about this topic in any other surveys, other than the National Self-Defense Survey conducted in 1993 by Kleck and Gertz (1995), who asked DGU questions of 4,977 people.” The BRFSS asked about defensive uses of guns in seven states in 1996, seven in 1997, and four in 1998.

Trying to get  valid DGU numbers is as complicated and as much of a fools errand as climatologists trying to get a “world temperature.”

The simple fact is that there are people that have personal firearms that are used to prevent themselves from being crime victims and there is no way that they can be properly accounted.