摘要：Objectives. We examined the relationship between gun ownership and stranger versus nonstranger homicide rates. Methods. Using data from the Supplemental Homicide Reports of the Federal Bureau of Investigation’s Uniform Crime Reports for all 50 states for 1981 to 2010, we modeled stranger and nonstranger homicide rates as a function of state-level gun ownership, measured by a proxy, controlling for potential confounders. We used a negative binomial regression model with fixed effects for year, accounting for clustering of observations among states by using generalized estimating equations. Results. We found no robust, statistically significant correlation between gun ownership and stranger firearm homicide rates. However, we found a positive and significant association between gun ownership and nonstranger firearm homicide rates. The incidence rate ratio for nonstranger firearm homicide rate associated with gun ownership was 1.014 (95% confidence interval = 1.009, 1.019). Conclusions. Our findings challenge the argument that gun ownership deters violent crime, in particular, homicides. Firearms cause more than 31 000 deaths annually in the United States. 1 Since the tragic shooting of 20 children and 7 adults in Newtown, Connecticut, in 2012, several states have enacted or debated legislation to restrict the availability of firearms. 2 Some gun rights advocates have argued that restricting the availability of guns might cause harm by removing an effective deterrent to crime. 3-5 Lott, for example, has suggested that reducing the number of guns held by law-abiding citizens might increase homicides because “it would be easier for criminals to prey on the weakest citizens, who would find it more difficult to defend themselves.” 5 (p11) Understanding whether increased gun ownership increases or decreases homicides is essential to inform public policy regarding measures to address firearm violence. Of particular interest is the question of whether higher gun ownership is associated with lower rates of stranger homicide (i.e., homicide committed by a person unknown to the victim) because such a relationship is consistent with the hypothesis that increased household ownership of guns deters violent crime by strangers who might otherwise have killed the potential victim. Multiple cross-sectional studies have demonstrated a correlation between higher gun ownership at the state level and higher overall state-specific rates of firearm homicide. 6-18 Most recently, we reported a strong and robust relationship between estimated gun ownership in the 50 states and firearm homicide rates over the period 1981 to 2010, while controlling for 20 potential state-level confounding variables. 19 None of these studies distinguished between stranger and nonstranger homicides. We are not aware of any published studies that have examined the relationship between gun ownership and stranger versus nonstranger homicide rates. Although the US Department of Justice regularly provides national statistics on rates of stranger versus nonstranger homicide, 20,21 we are aware of no published studies that report state-specific data on stranger versus nonstranger homicide. Understanding state-specific patterns of victimization in terms of the relationship between homicide victims and offenders, and identifying the trends in these patterns, would inform state efforts to reduce homicide rates. 22 Several studies have examined the relationship between homicide victims and offenders in specific settings, such as national youth homicides 22 ; national homicides 23,24 ; Allegheny County, Pennsylvania, homicides 25 ; adolescent homicides in North Carolina 26 ; homicides in Contra Costa County, California 27 ; and national homicides among intimate partners. 28 Nationally, between 1980 and 2008, of the homicides for which the relationship between victim and offender was known (63.1% of all homicides), approximately one fifth (21.9%) were stranger homicides. 20 We are not aware of any published data on how this may vary among states. In this article, we report and analyze stranger and nonstranger homicides at the state level during the period 1981 to 2010 and examine the relationship between those rates and state-specific household gun ownership during the same years. To the best of our knowledge, ours is the first study to report state-specific data on stranger and nonstranger homicide rates and examine the relationship between state-level gun ownership and stranger and nonstranger homicide rates, while controlling for differences in a wide range of state-level factors associated with homicide.
