A configurational analysis of 44 US mass shootings: 1975-2015

This study identifies the conditions under which civilian shooter events in the United States become mass episodes of killing. Hitherto, researchers have examined many individual-level variables associated with mass shootings including personal deprivation, family problems, mental illness, among others. Apart from a handful of quantitative studies, scholars have yet to provide a comparative scope to the multiplicity of factors that are influential in bringing about a mass murder. Adopting fuzzy-set qualitative comparative analysis, this study analyses (n = 44) civilian acts of violence that took place from 1975 to 2015 in which some shootings resulted in few deaths and others turned into mass bouts of killing. Empirical results reveal that no variables on their own are sufficient or necessary in accounting for the outcome of a mass shooting. Rather, configurations of causal conditions provide sufficient pathways and new insight into the particular circumstances under which a mass shooting is apt to take place in. The most salient of configurations tell us that mass shootings are prominently influenced by the combination of severe/multiple mental illnesses, a large number/high-powered guns and weak state gun law legislation. Another pathway reveals that mass shootings are also influenced by the interaction of radical ideology, severe/multiple mental illnesses, and high-state level gun ownership.