detail later in the report, the reasons for these differences may include a variety of factors such as socioeconomic status, urban/rural factors, and crime and policing in neighborhoods. Individual factors that may influence these differences include age; substance use; engagement or association with risky, delinquent, violent, or unlawful behaviors; propensity for suicide; and whether the perpetrator of a homicide is a family member, acquaintance, or stranger. Many of these factors are confounding, and careful analysis is required to understand the independent and interactive effects, supporting the need for rigorous research.
Availability of Firearms
Guns are widely used for recreation, self-protection, and work in the United States. However, it is difficult to determine the exact number and distribution of guns currently in homes and communities due to lack of data. Between 1986 and 2010, the domestic production of firearms increased by 79 percent, firearm exports increased by 11 percent, and firearm imports increased by 305 percent (ATF, 2012). A December 2012 poll found that 43 percent of those surveyed reported having a gun in the home (Gallup, 2013).
Defensive Use of Guns
Defensive use of guns by crime victims is a common occurrence, although the exact number remains disputed (Cook and Ludwig, 1996; Kleck, 2001a). 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 (Kleck, 2001a), in the context of about 300,000 violent crimes involving firearms in 2008 (BJS, 2010). On the other hand, some scholars point to a radically lower estimate of only 108,000 annual defensive uses based on the National Crime Victimization Survey (Cook et al., 1997). The variation in these numbers remains a controversy in the field. The estimate of 3 million defensive uses per year is based on an extrapolation from a small number of responses taken from more than 19 national surveys. The former estimate of 108,000 is difficult to interpret because respondents were not asked specifically about defensive gun use.
A different issue is whether defensive uses of guns, however numerous or rare they may be, are effective in preventing injury to the gun-wielding crime victim. Studies that directly assessed the effect of actual