- There are 3 major estimates of Defensive Gun Use (DGU) frequency per year:
- Gary Kleck and private surveys: approximately 2.5 million.
- National Crime Victimization Survey: approximately 100,000.
- Gun Violence Archive (based on police and media reports): less than 2,000.
- Surveys of rare events such as DGUs exaggerate their frequency due to false positives.
- While methodologically better, the NCVS estimate also suffers from false positives and is therefore likely an overestimate as well.
- Several of the crime predictions from Kleck’s survey are mathematically impossible, such as DGUs during burglaries and criminals being shot.
- Comprehensive empirical data (such as GVA’s) trumps survey data when they provide conflicting results.
The best available empirical evidence cataloging defensive gun use (DGU) comes from data compiled by the Gun Violence Archive (GVA), which found fewer than 1,600 DGUs in all of 2014, fewer than 1,400 DGUs in 2015, fewer than 2,000 in 2016, and slightly more than 2,000 in 2017. While these values represent the “floor” for DGU estimates (as they track only verified reports), the true value of DGUs is likely to be far closer to these estimates than estimates derived from surveys.
This estimate is in stark contrast to one routinely cited by the National Rifle Association (NRA) in which guns are used “millions of times a year” in self-defense – a claim which derives from a survey by Gary Kleck and Marc Gertz published in 1995 that indicated 2.5 million DGUs occur annually (which would equate to an average of 6,849 a day, or 285 an hour). This survey appeared to be corroborated by other similar small private surveys, and directly challenged estimates from the much larger National Crime Victimization Survey (NCVS) that place the total under 100,000 per year.
The discrepancy between Kleck, the NCVS, and GVA can be explained by a false positive problem, which is endemic in surveys of rare events. A false positive in this case is when somebody in the survey claims they had a DGU when they did not actually have one. A false positive can arise for a number of reasons, including social desirability bias (in which subjects are likely to lie about or exaggerate socially desirable behaviors); telescoping (in which respondents misremember when a real DGU occurred, and accidentally report one which occurred outside the time-frame asked about in the survey); and strategic reporting (in which respondents game their answers, aware that such surveys are often the basis of future policy).
In surveys of rare events, such as DGUs, these false positives are guaranteed to overwhelm any false negatives (where respondents say they didn’t have a DGU when they in fact did). As a result, Kleck’s 2.5 million DGU figure can be explained by a 1% false positive rate in his survey (and the same goes for NCVS figures, despite methodological efforts to limit them). In contrast, the hard data GVA collects from police and media reports would have to miss more than 99.9% of DGU cases in order to reconcile the empirical evidence with Kleck’s 2.5 million figure.
Further, many of the predictions from Kleck’s survey are irreconcilable with known facts about crime. According to Kleck’s estimates, guns were used defensively in 845,000 burglaries, yet we know from reliable victimization surveys there were fewer than 1.3 million burglaries in the United States at the time of the survey, and 33% had occupants in the home who were sleeping. Of those households, only 42% owned firearms. Even if burglars only targeted households that owned firearms, and those gun owners used guns in self-defense every time they were awake, the number would still be impossible to obtain (at most, only 117,000 defensive uses in response to burglaries would be even possible). Kleck’s analysis also implies hundreds of thousands of criminals are getting shot every year, yet there are no medical records to support this claim. While Kleck has claimed the majority of criminals simply never seek medical attention, data indicates more than 90% of criminals who have been wounded prior to incarceration seek medical attention.