Term mass shooting confuses public and masks phenomenon

Jodi Upton | USA TODAY

Depending on how you're counting, the shooting deaths of 14 people in San Bernardino, Calif. Wednesday was the 22nd mass shooting this year, or one of more than 300 in a near-daily epidemic.

Big difference. But the problem is one of definitions, sometimes used sloppily and interchangeably. The result: a very confused, and possibly hyperventilating public.

There is no official definition of a mass shooting. The closest is by the Congressional Research Service, which says it is four or more people killed with a firearm, not including the killer. That's pretty similar to the FBI's definition of a mass killing, about 75% of which are committed with a firearm, according to USA TODAY research. (Other weapons include knives, a baseball bat, even one case where a father threw his children off a bridge). So far this year, there have been 29 mass killings, resulting in 155 deaths. Of those, 22 incidents were shootings.

But several other sources use alternate definitions, regardless of whether anyone dies. For example, two widely used sources on mass shootings include Stanford Mass Shootings, and Mass Shooting Tracker, The first defines a mass shooting as three or more people shot,but not necessarily fatally; the killer(s) is not counted. The second defines it as four or more people shot, not necessarily fatally. It may include the killer(s).

Researchers say headlines that suggest a 'mass shooting' occurs daily, on average, are misleading. In the eyes of the public, that translates into a San Bernardino-style shooting nearly every day.

"That definition of four or more shot, rarely translates to four or more killed. One-third of these 'mass shootings' result in no fatalities, and only 5% are mass killings," says James Alan Fox, Lipman Family Professor of Criminology, Law & Public Policy at Northeastern University. "However, this scary one-a-day statistic is rolled out whenever there is a large-scale mass killing, allowing unsophisticated readers to make the wrong connection."

Fox also points out that the one-a-day statistic is devoid of any benchmark. Since most counting of public shootings occurred after Sandy Hook almost exactly three years ago, it's difficult to make comparisons.

"Without historical context, we get hysterical response." says Fox. "If it were possible (and it really isn’t) to go back to 2005 and count number of shootings with 4+ injured, I’m sure it would be on par with today’s figures." Fox says the central problem is that the idea of a 'mass shooting' conflates how the crime occurred, with how many victims. And they are really separate hallmarks.

It also makes it really hard to understand which way such incidents are trending.

Mass killings -- by firearm or other means -- have not increased since 2006; they are consistently about two dozen a year. But there is some indication that incidents of 'active shooters' may be increasing. According to an FBI report released last year, there were 160 'active shooter' events between 2000 and 2013. An average of 6.4 incidents occurred in the first 7 years studied, and an average of 16.4 occurred in the last 7 years. But critics say early years are under counted, which likely explains the increase.

Anyone waving a gun in a public place is threatening, and should be counted to understand such episodes of violence. But the FBI is far more likely to call such incidents an 'active shooter' because it makes no distinction between whether deaths have occurred, and conveys the idea that it's an ongoing situation.

That's precisely why the Congressional Research Service report called for better data collection among government agencies.

Currently, the FBI collects data on all homicides in the U.S., though -- because of the way individual police agencies report incidents -- nearly half of the mass killing cases included in the Supplemental Homicide Report are incorrect. The report includes cases that never occurred, and leaves out cases that did, according to USA TODAY research.

Clarifying the definition and improving reporting -- whether it's mass killing, mass shooting or active shooter, is critical to understanding and responding to the phenomenon, the CRS report noted.

"Mass shootings are arguably one of the worst manifestations of gun violence," the report notes. And everyone has a different definition "contributing to a welter of claims and counter-claims about the prevalence and deadliness of mass shootings. With improved data, policymakers would arguably have additional vantage points from which to assess the legislative proposals that are inevitably made in the wake of these tragedies."