Mass shootings are associated with a jump in the number of federal background checks for gun purchases, according to research published in The Social Science Journal in 2015.

Lacey N. Wallace, an assistant professor of criminal justice at Penn State Altoona and the author of the study, decided to investigate the topic after discovering how little research had been done on guns.

“Years ago, I was teaching an Introduction to Criminology class. One of my students asked a question about Castle Doctrine laws. I didn’t know the answer to his question, but I assured him I would check into it and have an answer for him the next class,” she explained to PsyPost.

“I was stunned to discover that there was basically no research on the topic, and a lack of research on many other gun-related topics. That motivated me to start studying gun policy and gun behavior.”

Wallace used data from the National Instant Criminal Background Check System to approximate the number of gun sales in the U.S between 2000 and 2010.

She found that mass shootings were associated with an increase in the number of monthly background checks. This was true even after controlling for monthly violent crime counts, state demographics, the election of President Obama, and the relative frequency of Google searches for gun control and related terms.

But the effects of mass shootings on gun acquisition appeared to fade after about 3 to 4 months.

“After a mass shooting, fear can lead people to purchase firearms. Some people are afraid of being a victim themselves, or fear for the safety of those they love. Other fear stricter gun control and worry that their ability to purchase or own a firearm might be threatened,” Wallace explained.

Another study, published in the Annals of Internal Medicine in 2017, appears to have confirmed the trend. That study found large increases in handgun acquisitions in California immediately following the mass shootings in Newtown, Connecticut in 2012 and San Bernardino, California in 2015.

Currently, the National Instant Criminal Background Check System provides some of the best data on gun purchases. But it also has significant limitations. Some gun sales do not result in a background check and a background check may be used to issue a concealed carry permit rather than to authorize the purchase of a new firearm.

“Background checks don’t give a complete view of gun purchasing since private sales often do not require a background check. We need a lot more research on how and when people purchase gun accessories, like bump stocks,” Wallace said.

“I think it is important that we, as researchers, don’t shy away from discussing guns and gun violence. While the topic is controversial, it is also important to public health. While federal funding for gun research is still severely limited, that doesn’t mean we should not try to get a better understanding of who owns guns and why.”

The study was titled “Responding to violence with guns: Mass shootings and gun acquisition“.