A total of 373 mass shootings occurred in the United States in 2015, creating an average of more than one per day, according to two online databases.

The sources, Gun Violence Archive (GVA) and a Reddit thread called GunsAreCool, both define mass shootings as an incident in which four or more people were shot at the same general time in the same general location, which is documented in the video above. The GVA, however, stipulates that all four individuals must be victims of the shooting, whereas the Reddit thread includes perpetrators in its final count. 

This broad definition means that an array of dissimilar events fall into the same category: large-scale attacks, like the San Bernardino shooting, in which 14 random people died and 17 were hurt; targeted murders, such as the shooting of a journalist during a live broadcast in Virginia, which killed three (including the gunman) and wounded one; alleged gang-related violence in Chicago that resulted in no fatalities, but four injuries.

Evidence tags and debris surround the SUV thought to be the getaway vehicle of the husband and wife gunmen in the San Bernardino mass shooting

Neither database is an official source of information and they collect statistics differently. GunsAreCool crowdsources info from Reddit users, while the GVA employs 14 staff members fulltime who work on an array of research related to gun violence.

Furthermore, the sites either contain minor errors themselves or have discrepancies between them. GunsAreCool, for instance, lists 372 mass shootings as of December 30, but skips numbers 124 and 336, meaning that it contains a total of 370 incidents. The GVA, however, documents 329 events throughout the course of 2015. The above map of each shooting contains a cross-referenced combination of the two in chronological order.

Despite these small inaccuracies or differences, both sources hope that this information helps redefine the term altogether.

“The most obscene incidents of gun violence usually do not make the mainstream news at all. Why? Because their definition is incorrect,” GunsAreCool explains, referring to the FBI’s metric for mass killing – an event in which four or more people die, excluding the shooter. By this standard, the November incident in New Orleans that wounded 17 people but killed no one does not count as a mass shooting.

But according to some experts, trying to create a new definition is problematic. When neither circumstances nor the degree of injury is taken into account, they claim that inaccurate conclusions can be drawn.

“Without historical context, you can encourage hysterical responses,” explained James Alan Fox, a professor of criminology, law & public policy at Boston’s Northeastern University.

He also pointed out that these statistics are often only released in the wake of a significant mass murder, which clouds the public’s perception of the issue even more.

Because of these broad definitions, Mr Fox doesn’t see much value in the databases.

“Why don’t we talk about people killed by gunfire – 40 or 50 a day. And we have data on that – data going back decades,” he said.

People fill the street in front of the historic Emanuel African American Methodist Church during the Sunday morning service, four days after nine of its members were shot to death in the building in Charleston, South Carolina

“So why are we searching for this new definition, which has no historical context, which is very misleading?”

But while organisations the like GVA are attempting to do just that - redefine mass shootings - even its executive director agrees that the conversation needs to shift from the terminology to the events themselves.

"The discussion on definition takes away from the problem of victims," explained Mark Bryant by phone. "Each day a group of lives gets disrupted and a group of families gets disrupted."