Do assault weapons bans work?

Published 8:14 pm Friday, November 29, 2019

This summer, I appeared on VICE News to talk about my research on the national assault weapons ban. That prompted a Pennsylvania politician’s office to contact me to ask if I would analyzed whether statewide assault weapons bans would work or not. Similarly, retiring US Senator Johnny Isakson (R-Georgia), a frequent Skype guest of our class, made a similar push for the CDC to study gun violence. I got my LaGrange College students to research the topic, and here’s what we found.

My freshman students gathered data from The Washington Post on whether or not a particular state had an assault weapons ban on all mass casualty shootings in recent years, from the 1980s to today.

We found that there were eight states of 51 entities (50 states plus Washington D.C.) had a statewide or district assault weapons ban, while 43 did not. We also noted that 27 of 51 cases had a mass casualty shooting, while 24 did not.

Among the eight states with a ban, half of them had a mass casualty shooting and the other four did not. Among the 43 states or districts without an assault weapons ban, 23 had a mass casualty shooting, and the other 20 did not.

Running a chi-square test, we found that there was no difference in results between states with a ban and those without a ban, when it came to mass casualty events. States with a ban were just slightly less likely to have such a shooting (states without a ban were a little more likely to have a shooting), but results were not statistically significant. Reports often indicate that the shooter purchased the gun from a state without such a ban, but we’ll have to look into that next time.

My research methods students noted that not all mass shootings had an assault weapon involved. So, I double-checked the numbers. Indeed, they are right. Analysis of 81 mass shootings since the assault weapons ban was allowed to expire in 2004 revealed 12 cases where an assault weapon was involved, along with 50 semiautomatic gun cases, and 19 cases where the gun or guns used were fully automatic or semi-automatic, which was very interesting. I discovered that only two states with a ban had mass casualty shootings, while the other six states with a ban did not. The results were still not statistically significant in a new chi-square test, however.

I reran the numbers from 1982 to 2019, and found that before the assault weapons ban, there were five mass casualty shootings in 12 years, while there were three mass casualty shootings in the 10 years that the assault weapons ban was in effect (1995-2004). Since the ban was allowed to expire, there have been 12 mass casualty killings in the 14 plus years since then. It seems the Federal Assault Weapons Ban was more effective at reducing these killings than statewide bans.

Freshmen students Andrue Davis, Ashton Kincaid, Briana Whiteside, Cameron Rockmore, Christopher Taylor, DeQueze Fryer, Gabriel Pallo, Hayleigh Reeves, James Thrailkill, Jeremiah Thurmond, Katelyn Peters, Kylie Neal, Len Spivey, Malachi Parker, Morgan Ciesla, Natalie Gigli, Peter Anderson, Ronnell Coleman, Scott Kondroik, Sierra Hall, Stoney Cheeks, William Covington, and my teaching assistant Peter Alford all contributed to the data collection. 

My research methods students Tia Braxton, Melanie Chambers, Natalie Glass, Porter Law, Jaydon Parrish, Elijah Robertson, Payton Smith, Jason Timms, Caleb Tyler, Andrew Valbuena and Benjamin Womack contributed to the data analysis.