By some accounts, there is an average of at least one mass shooting in the United States each day. But tied to that is a definition that contrasts with a more traditional definition of a mass shooting.
On Wednesday, two shooters killed 14 people and injured at least 21 in San Bernardino, California -- the 355th mass shooting this year alone, according to a Washington Post analysis. That leaves many wondering when we'll see the same headline repeated -- and if mass shootings can be stopped.
The Washington Post analysis uses data from Mass Shooting Tracker, a database started by Redditors, and reflects the number of incidents in which four or more people were killed or injured by a shooter (including the shooter).
This stands in contrast with the FBI's definition of a mass shooting, which is one of the most commonly accepted ones: an incident in which three or more people are killed as part of a single shooting, excluding the shooter. (Prior to 2013, that number was four.)
microcontent">That means if 40 people were shot but only two died, the FBI would not consider it a mass shooting -- such as the Virginia shooting during a live TV broadcast.
Other definitions, however, draw a more detailed picture.
Data suggest a upward trend in the frequency of mass shootings. A study conducted by researchers from Harvard's School of Public Health and Northeastern University found that the frequency of mass shootings has tripled since 2011; a more detailed 2014 FBI analysis shows an uptick in active shooter situations, or incidents in which "an individual [is] actively engaged in killing or attempting to kill people in a confined and populated area." However, that data should be read with a caveat.
The Harvard/Northeastern study relied on a definition of mass shooting which excluded domestic violence incidents. They looked only at incidents in which the shooter and victims did not know each other, and in which the shooter murdered four or more people.
It may seem unnecessarily picky to argue over what constitutes a mass shooting, but these definitions matter. That's why there is a need for more distinct vocabulary, says Deborah Azrael, the associate director of the Harvard Youth Violence Prevention Center.
One problem, Azrael notes, is that these varying definitions complicate the public comprehension of "mass shooting" headlines. "In some ways, it’s a mess because everyone calls these mass shootings," she says.
Databases like Mass Shooting Tracker should be approached with a degree of caution, Azrael added, given the data is not vetted in a systematic way -- but the information they capture, which tracks injuries as well as deaths, offers data that is not available from the FBI. "To focus only on mortality is to lose an important part of the damage that guns inflect," she says.
James Fox, a professor of criminology at Northeastern University, argues that mass shooting incidents have not increased, according to the FBI's historical definition of four or more killed. Fox says on average, there are about 20 incidents annually that follow this definition, and that has not changed.
"One can take virtually any period of months or years during the past few decades and find a series of shootings that seemed at the time to signal a new epidemic," Fox wrote in an op-ed for USA Today.
“The only increase has been in fear, and in the perception of an increase,” Fox said in an interview with the New York Times this week.
But that would mean Fox is working off a definition that "all mass shootings are alike," Azrael tells Mashable. We can, in fact, distinguish among them, Azrael says. A majority of mass shootings -- 57% -- were incidents of domestic or family violence, according to a recent report from Everytown for Gun Safety, a gun-control advocacy group.
Instead, we need a new vocabulary and more research to determine whether cases in which four people are shot are really different than cases in which four people are killed.