Describing a “mass shooting”: the role of databases in understanding burden

Abstract

BackgroundThe mass shooting phenomenon has gained much attention lately as this form of gun violence appears to increase in frequency. Although many organizations collect information on mass shootings (fatal and nonfatal injuries), no federal definition of this phrase exists. The purpose of this study was to highlight the different statistics that result among databases that define and track “mass shootings.” Establishing definitive guidelines for a mass shooting definition could improve research credibility when presenting evidence to policy makers.MethodsWe obtained data for mass shootings that occurred in 2017 from four sources: Gun Violence Archive, Mother Jones Investigation, Everytown for Gun Safety, and FBI’s Supplemental Homicide Report. We also examined FBI’s Active Shooter Report to compare the mass shootings datasets with active shooter situations, which have been federally defined. First, we examined the overlap among databases. Then, we applied the strictest fatal mass shooting definition to the mass shooting datasets to determine whether the differences in databases could be contributing to differences in fatalities and injuries recorded.ResultsGun Violence Archive recorded the most mass shooting incidents at 346 incidents in 2017, while Mother Jones only recorded 11 cases. Only 2 events were found in all four mass shooting datasets. When the strictest definition – four or more individuals fatally shot – was applied to all datasets, the number of mass shootings in 2017 ranged from 24 (Gun Violence Archive) to 5 (Mother Jones), but incidents collected still varied.ConclusionsThere is much variety in statistics obtained from the different sources that have collected mass shooting information, with little overlap among databases. Researchers should advocate for a standard definition that considers both fatalities and nonfatalities to most appropriately convey the burden of mass shootings on gun violence.

Evidence concerning the regulation of firearms design, sale, and carrying on fatal mass shootings in the United States

“…We also only examined fatal mass shootings, in which the number of fatalities rather than casualties determined whether an incident was included in the analysis. Booty, O'Dwyer, Webster, McCourt, and Crifasi () have raised the issue of inconsistencies in mass shooting databases that define “mass shooting” differently, and we acknowledge that our results are influenced by the definition that we have chosen.…”

Psychotic symptoms in mass shootings v. mass murders not involving firearms: findings from the Columbia mass murder database

“…First, relying on descriptive data, without incorporating a comparison group, renders the results particularly susceptible to various biases, including selection bias. Second, the definition of mass shooting as involving three v. four victims have been inconsistent across studies, with no attempts within a given report to determine whether alternative definitions alter results (Booty, O'Dwyner, Webster, McCourt, & Crifasi, 2019). Additionally, reports have generally focused on mass shootings occurring in the USA alone and no earlier than 1966, yielding varied sample sizes limited to several hundred events.…”

Firearm Purchasing and Firearm Violence in the First Months of the Coronavirus Pandemic in the United States

“…We use the term ‘injuries’ to include both nonfatal injuries and deaths. GVA data have been used for research on legal intervention shootings, 17 firearm homicides, 18 mass shootings, 19,20 and community violence 21 and have performed well relative to other sources. 17,19…”

“…GVA data have been used for research on legal intervention shootings, 17 firearm homicides, 18 mass shootings, 19,20 and community violence 21 and have performed well relative to other sources. 17,19 We developed a directed acyclic graph to identify a minimum set of time-varying covariates needed to control for confounding ( Supplementary Figure 1). Covariates include monthly COVID-19 cases and deaths per population, state stay-at-home orders, average monthly movement (a measure of adherence to social distancing recommendations), and average monthly temperature and precipitation.…”