Google searches, gun sales and accidental gun deaths increased in the four months after the 2012 Sandy Hook mass shooting.| Carla Schaffer/ AAAS
In the four months after the 2012 mass shooting at Sandy Hook Elementary School in Newtown, Connecticut, the number of guns purchased in the U.S. rose by 3 million compared to typical sales levels and 60 additional accidental deaths related to firearms occurred, a new study estimates.
The results, published in the December 8 issue of Science, suggest a direct relationship between increased exposure to guns and the risk of gun-related deaths, said Wellesley College researchers Phillip Levine and Robin McKnight.
On December 14, 2012, 20-year-old Adam Lanza fatally shot 20 children and six adults at Sandy Hook Elementary School. As is common in the aftermath of many mass shootings in the U.S., the tragic loss of life was closely followed by heated debate surrounding the country's gun laws.
Among the many reports that followed the shooting, a graphic published by the New York Times caught the attention of Levine and McKnight. The graphic showed a stunning spike in gun sales across the country. This spike in gun sales, and thus likely increased access and exposure to guns, prompted the researchers to explore whether there was a similar spike in accidental deaths related to firearms.
Levine noted that causal relationships — such as that between increased exposure to guns and increased risk of gun-related death — can be very difficult to pinpoint. But the trends that occurred after the Sandy Hook shooting presented an opportunity to better explore this relationship. "At precisely the time that gun sales jumped, do we see a sudden increase in accidental gun deaths? And when the spike in sales ended, did the spike in deaths end? [If we do], the exact timing makes it less likely to be a coincidence," Levine explained.
When Levine and McKnight examined Google data between 2010 and 2014, they found that weekly search volumes for the terms "buy gun" and "clean gun" surged in the four months following the shooting at Sandy Hook — with searches for "buy gun" increasing four-fold. Particularly high spikes for these search terms occurred following two occasions when President Obama spoke about the need for new gun control legislation.
"The fact that the spike in deaths is larger in states with the largest increase in gun sales reinforces the interpretation of a causal impact of the gun exposure."
Both Google search terms can be associated with increased exposure to guns, suggesting that more guns are likely to be purchased or more guns are being taken out of storage for cleaning.
To estimate gun sales during the months after the shooting, Levine and McKnight looked at the number of federal background checks on individuals seeking to purchase a firearm from a licensed dealer as a proxy. Based on the data, they estimate that an additional 3 million guns were sold during this same four-month window, compared to typical sales.
Next, Levine and McKnight looked at two different datasets capturing deaths across the country. Their results show that, as gun sales (and presumably people's exposure to guns) were increasing, accidental deaths related to firearms also increased. In total, the researchers estimate that 40 additional accidental deaths occurred among adults and 20 additional accidental deaths among children.
Levine and McKnight uncovered another factor in determining a causal relationship: spikes in accidental firearm-related deaths were concentrated in states with larger increases in per capita gun sales. "The fact that the spike in deaths is larger in states with the largest increase in gun sales reinforces the interpretation of a causal impact of the gun exposure," McKnight said.
"The public health consequences are likely to be even greater than what we identified in our study because there are roughly 12 times as many non-fatal accidental firearm injuries among children as there are deaths," explained McKnight.
Although the precise timing of increased exposure to guns and increased accidental deaths strongly suggests that the two factors are linked, Levine and McKnight emphasize that they are unable to determine the extent of this relationship.
In the same issue of Science, Philip Cook of Duke University and John Donohue of Stanford University published a Policy Forum discussing the challenges of gun research. In their article, the authors underscore that although teasing apart the intricacies between gun laws and related violence can be very difficult, evidence increasingly shows that stricter gun laws in the U.S. can reduce crime. For example, evidence suggests that additional prison time for gun use in a violent crime can reduce robberies involving guns. Bans on gun possession by those convicted of domestic violence also have resulted in a reduction in deaths among women by their partners.