Has gun violence gotten better or worse over time?
The answer depends largely on how you define “gun violence” and how you choose to view the data that exists.
Those who believe in the need for stronger gun reform might point out that the number of mass-shooting fatalities and incidents has risen over the past several years while opponents of new gun controls will argue that the rate of firearm homicides has decreased in recent years.
Both arguments are based in fact. They are merely different sides of the same coin.
Mass shootings: Congressional report
The Congressional Research Service defines “mass murder” as the murder of four or more victims in one incident and location. This matches the FBI’s definition, but the CRS narrows its data to victims murdered with a firearm.
The CRS analysis indicates that 317 mass shootings occurred between 1999 and 2013 in the United States, causing 1,554 fatalities and 441 injuries.
Based on five-year averages, the CRS data shows an uptick in mass shooting incidents, fatalities and injuries from 2009-2013.
“You can clearly see an increase in the number of mass shootings and also the number of victims per event,” said Dr. Cassandra Crifasi, an associate professor at the Johns Hopkins Center for Gun Policy and Research.
The “numbers [are] going up, and we’re seeing more people wounded and killed as a result of these mass shootings,” she said.
The Federal Bureau of Investigation also released a study of 160 active-shooter incidents between 2000 to 2013, noting their increased frequency.
In their study, the bureau defined an “active shooter” as an individual actively engaged in killing or attempting to kill people in a populated area.
They said the number of incidents has increased from an an average of 6.4 incidents in the first seven years studied to an average of 16.4 in the last seven years. The average number of fatalities and injured more than tripled from the first seven years to the last seven years.
Mass Shooting Tracker data
Meanwhile Mass Shooting Tracker, a crowd-sourced website, defines a mass shooting as a single incident where four or more people other than the shooter are shot or killed at the same time and location.
The Mass Shooting Tracker data shows that the number of fatalities, injuries, and incidents have all increased over the past three years.
However, the data from Mass Shooting Tracker only goes back to 2013, so it does not offer any long-term trends.
Regardless of how one chooses to define mass shootings, the data shows that mass shootings are increasing in frequency as well as in the number of fatalities and injuries.
Firearm homicide rates decreasing
Nonetheless, mass shootings make up only a small percentage of firearm homicides. While most Americans believe the number of firearm homicides has risen, the rate of firearm homicides actually has decreased in recent years.
Dr. Kun Chen, a statistics professor at the University of Connecticut, said that rates are a much better measure than the raw count.
“When comparing or analyzing the risk levels of different geographical areas or groups, it is very important to take into account the factor of population size…Using raw counts to make inference can be misleading, as the area or group of larger size will appear to be at a higher risk level,” said Chen.
Adjusting for age
The Pew Research Center found that between 1993 and 2000, the firearm homicide rate dropped by approximately half, from 7.0 homicides to 3.8 per 100,000 people. Since then, Pew states, the gun homicide rate has remained relatively steady.
However, the Centers for Disease Control and Prevention also computes the age-adjusted death rates per 100,000 people, based on populations reported in the 2000 census.
Age-adjusted death rates are preferable to crude death rates because they are a way to make fairer comparisons between groups with different age distributions, according to Crifasi.
For example, a county with a higher percentage of elderly people may have a higher rate of death than a county with a younger population, merely because the elderly are more likely to die.
Like the Pew data, the age-adjusted firearm homicide rates from the Centers for Disease Control and Prevention illustrates a decline in firearm homicide rates from 1993 to 2000.
Additionally, the Centers for Disease Control and Prevention shows that the age-adjusted firearm homicide rate has continued to decrease instead of stabilizing over the past several years from 4.3 homicides in 2006 to 3.5 in 2014.
Homicides and suicides
Despite some upticks in firearm homicide rates in urban areas, Crifasi said, there has generally been a decrease “as we have more effective strategies to deter criminal access to firearms as well as improved policing strategies, focusing on dangerous individuals as opposed to places.”
While the age-adjusted firearm suicide rate has declined overall since 1993, it has risen in recent years from 5.6 suicides in 2006 to 6.3 in 2014 per 100,000 people.
In fact, the nation’s overall gun death rate has declined 31 percent since 1993. This total includes homicides and suicides, as well as fatal police shootings, accidental shooting deaths and those of undetermined intent.