An analysis of recent school shootings suggests a way to make them less likely: Mandatory background checks.

States that required background checks for gun buyers were about half as likely to experience a school shooting compared with states with no such requirement, a new study reports. In addition, the handful of states that forced people to submit to background checks before purchasing ammunition had dramatically lower odds of a school shooting.

The findings are based on an examination of 154 school shootings that occurred in the United States between Jan. 1, 2013, and Dec. 31, 2015. The results were published Tuesday in the journal Injury Prevention.

Researchers from Boston University, Columbia University and the University of Texas Southwestern School of Medicine combed through media reports to identify as many school shootings as they could. For the study, they defined a school shooting as “an incident when a firearm was discharged inside a school building or on a school campus or grounds.”


After searching through more than 18,000 news sources in the LexisNexis Academic database, they tallied 35 school shootings in 2013, 55 in 2014 and 64 in 2015. Among those 154 incidents, 45 resulted in the death of someone other than the shooter, and the remaining 109 involved non-fatal injuries. (The researchers suspect there were actually more instances of guns being fired on school grounds, but they didn’t make the news because they didn’t result in any injuries.)

More than half (55%) of these 154 school shootings occurred on K-12 campuses, and most (66%) were intentional, the researchers found. Nearly all (99%) of the shooters were boys, and more than one-third (36%) were known to be students. Students also accounted for 59% of the victims who died of gunshot wounds.

The school shootings were spread among 39 states. Most of these states had shootings in the single-digit range, but Georgia had 15, Florida and Texas each had 14, North Carolina had 12 and Tennessee had 10. Eleven states — Alaska, Connecticut, Hawaii, New Hampshire, New Jersey, New York, North Dakota, Rhode Island, Vermont, West Virginia and Wyoming — had no school shootings between 2013 and 2015.

During the study period, 17 states (California, Colorado, Connecticut, Delaware, Hawaii, Illinois, Iowa, Maryland, Massachusetts, Michigan, Nebraska, New Jersey, New York, North Carolina, Pennsylvania, Rhode Island and Washington) and the District of Columbia had laws requiring background checks for at least some kinds of gun purchases at least some of the time.


Those background checks may have made a difference — the incidence of school shootings was 45% lower in states that required them compared with states that didn’t, the researchers reported.

In addition, four states (Connecticut, Illinois, Massachusetts and New Jersey) required mandatory background checks for would-be ammunition buyers during some or all of the study period. The risk of a school shooting was 89% lower in these four states than in the rest of the country, the research team found.

These associations aren’t proof that background checks reduced the risk of school shootings. All they show is a correlation, not a causal relationship.

And even these correlations should be considered preliminary, said study leader Bindu Kalesan, director of the Center for Clinical Translational Epidemiology and Comparative Effectiveness Research at Boston University.


Although 154 school shootings may sound like a lot, it’s not enough for a statistical analysis that takes account of the many other factors that could plausibly influence the risk of a school shooting, Kalesan said. If the team did have enough data to do the proper adjustments, they might see the relationship between background check laws and school shootings weaken, or even disappear altogether, she added.

“It is important to interpret our results in the light of these limitations,” Kalesan said.

Still, with school shootings occurring at a rate of about one per week, it’s important to learn more about the factors that might make these incidents less common.

For instance, preliminary study results suggest that state spending on K-12 education and mental health services were inversely correlated with the risk of a school shooting. Perhaps mental health professionals are able to identify people at risk of using guns to harm themselves or others, the researchers wrote. It’s also possible that the well-known relationship between investment in education and reduction in crime extends to school shootings, they noted.


More research — and more data — will be necessary to get a clearer picture, Kalesan said.

“What we really need is [a] national registry and granular information” about school shootings, she said.

karen.kaplan@latimes.com

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