defensive gun ownership and lower suicide rates (Hemenway et al., 2001). Neighborhood levels of gun ownership could even conceivably be affected by neighborhood suicide rates: suicide rates might contribute to a community’s perceived level of violence, whether people are aware of making such a link or not.
This concern is not unique to ecological studies, but has been generally ignored in this literature. There have been few systematic efforts to explore or model possible confounders of the association between gun ownership and suicide risk. Two studies by Hemenway and associates are suggestive. First, Hemenway et al. (2001) investigated the hypothesis that persons who live in communities with higher levels of mutual trust may be at lower risk of suicide (because of increased social support), and lower risk of gun ownership and less likely to own firearms (because of decreased motivation for defensive gun ownership). They found that, across U.S. states, lower levels of mutual trust and civic engagement, as reported on the General Social Survey and on the Needham Lifestyle Survey, were associated with a higher fraction of suicides committed with a gun. This study did not examine the association between social capital, firearm ownership, and overall suicide rates. Hemenway and Miller (2000) investigated the hypothesis that regions with higher rates of firearm ownership were characterized by higher rates of major depression, which is known to be an important independent risk factor for suicide. They found that the cross-sectional, regional association between firearm ownership and suicide rates was not explained by differences in the regional prevalence of major depression and serious suicidal thoughts.
Research linking firearms to suicide (and violence more generally) is limited by the lack of detailed information on firearms ownership (see Chapter 2). The existing surveys cannot be used to link ownership to outcomes of interest and, for that matter, cannot generally be used to draw inferences about ownership in more precise geographic areas (e.g., counties) that are often of interest in ecological studies. The GSS, which collects individual and household information on firearms ownership over time, is representative of the nine census regions and the nation as whole. Other surveys—the Behavioral Risk Factor Surveillance System (BRFSS) and the Harvard Injury Control Research Center Survey (HICRC)—collect information on gun ownership prevalence rates representative of individual states in certain years.2