DEFENSIVE GUN USES - NEW EVIDENCE FROM A NATIONAL SURVEY

The number of civilian defensive gun uses (DGUs) against criminal atta ckers is regularly invoked in public policy debates as a benefit of wi despread private ownership of firearms. Yet there is considerable unce rtainty for the prevalence of civilian DGUs, with estimates ranging fr om 108,000 (using the National Crime Victimization Survey) to 2.5 mill ion (using smaller telephone surveys) per year. In this paper we analy ze the results of a new national random-digit-dial telephone survey to estimate the prevalence of DGU and then discuss the plausibility of t he results in light of other well-known facts and possible sources of bias in survey data for sensitive behaviors. Because DGU is a relative ly rare event by any measure, a small proportion of respondents who fa lsely report a gun use can produce substantial overestimates of the pr evalence of DGU, even if every true defensive gun user conceals his or her use. We find that estimates from this new survey are apparently s ubject to a large positive bias, which calls into question the accurac y of DGU estimates based on data from general-population surveys. Our analysis also suggests that available survey data are not able to dete rmine whether reported DGU incidents, even if true, add to or detract from public health and safety.