Estimating the Global Prevalence of Mass Public Shootings

• Published date: 01 December 2023
• DOI: http://doi.org/10.1177/0306624X221139070
• Author: Grant Duwe,Nathan E. Sanders,Michael Rocque,James Alan Fox
• Date: 01 December 2023
• Subject Matter: Articles

https://doi.org/10.1177/0306624X221139070

International Journal of

Offender Therapy and

Comparative Criminology

2023, Vol. 67(16) 1642 –1658

© The Author(s) 2022

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DOI: 10.1177/0306624X221139070

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Article

Estimating the Global

Prevalence of Mass Public

Shootings

Grant Duwe1, Nathan E. Sanders2,

Michael Rocque3, and James Alan Fox4

Abstract

Previous studies have yielded widely divergent conclusions about the percentage of

all mass public shootings globally that take place in the US, ranging from a low of 3%

to a high of 36%. Because of documented underreporting of lower-severity attacks

involving fewer than 10 victim fatalities in US cases in these studies, it is reasonable

to assume that this underreporting issue also applies to their measurement of

mass public shootings outside the US. To estimate the total number of mass public

shootings worldwide, we use multiple assumptions and modeling approaches,

including a hierarchical Bayesian model. Our estimates show the US accounted for

anywhere between 16% and 26% of the world’s mass public shootings during the

1976 to 2012 period. These estimates suggest the US share of the total is between

four and six times higher than its 4% share of the world’s population.

Keywords

comparative criminology, gun violence, hierarchical Bayesian modeling, lethal mass

violence, mass public shootings

Are mass public shootings, in which four or more victims are fatally shot in a public

space within 24 hours, a uniquely American phenomenon? Or is this type of violence

just as likely to occur outside the United States? Prior research has offered widely

1Minnesota Department of Corrections, St. Paul, USA

2NSanders LLC, North Andover, MA, USA

3Bates College, Lewiston, ME, USA

4Northeastern University, Boston, MA, USA

Corresponding Author:

Grant Duwe, Minnesota Department of Corrections, 1450 Energy Park Drive, Suite 200, St. Paul, MN

55108-5219, USA.

Email: grant.duwe@state.mn.us

1139070IJOXXX10.1177/0306624X221139070International Journal of Offender Therapy and Comparative CriminologyDuwe et al.

research-article2022

Duwe et al. 1643

divergent assertions about the prevalence of mass public shootings in the United States

relative to the rest of the world. For example, one study found the US, which makes up

about 4% of the global population, accounts for only 3% of all mass shootings (Lott &

Moody, 2019). Other research, however, reports the US share of mass public shootings

is six to nine times higher than its percentage of the world’s population (Lankford,

2016, 2019, 2020; Silva, 2023). When the focus has been on developed countries,

previous studies have reported the US accounts for 66% to 73% of all mass public

shootings (Lemieux, 2014; Silva, 2023).

To measure the incidence of mass public shootings in the US and abroad, existing

research has relied exclusively on news coverage or on published lists (e.g., Active

Shooter reports by the NYPD and FBI and the Global Terrorism Database) that have, in

turn, relied almost exclusively on news coverage as a data source. As numerous studies

have shown, however, using the news media as the sole source of data results in under-

reporting (Duwe, 2007; Fox et al., 2021; Krouse & Richardson, 2015; Overberg et al.,

2013). In this study, we use an approach relatively new to criminology to estimate the

extent to which mass public shootings occurring outside the US have been underre-

ported. Recent research has shown that mass public shootings generally follow a heavy-

tailed distribution in which only a small number of incidents are at the extreme end of

the right tail in terms of severity (with sizes several times the mean) while most events

are of relatively low severity (Duwe et al., 2022). Because the rarest and most severe

cases generally receive greater news coverage (Fox et al., 2021), it is likely that previ-

ous studies have accurately accounted for these cases both in the US and abroad.

As we demonstrate below, however, most prior studies have not identified a sub-

stantial number of the less severe, but also more frequent, mass public shootings that

occurred in the US. To estimate the extent to which this underreporting problem has

affected their documentation of mass public shootings outside the US, we leverage

what is known about the distribution of US cases by incidence and severity. More

specifically, we apply heavy-tailed distributions to generate estimates of the overall

number of mass public shootings that took place outside the US between 1976 and

2012 and the completeness of the observed data. In doing so, this study provides a

more accurate estimate of the global prevalence of mass public shootings and, more

narrowly, the extent to which these incidents have occurred outside the US.

Defining and Measuring Mass Public Shootings

While some global mass public shooting research (e.g., Lemieux, 2014) do not define

“mass shootings” or describe how data were collected, the research by Lankford

(2016, 2019, 2020), Lott and Moody (2019, 2020) and Silva (2022) has generally

provided such information. For example, borrowing heavily from the “active shooter”

definition advanced by the Department of Homeland Security, Lankford (2016, p. 4)

defined mass public shootings as attacks that “must have (a) involved a firearm, (b)

appeared to have struck random strangers or bystanders and not only specific targets,

and (c) not occurred solely in domestic settings or have been primarily gang-related,

drive-by shootings, hostage-taking incidents, or robberies.” In addition to focusing