Can Internet search data illuminate the gun policy debate?

Gun violence is a major cause of death in the United States, yet the data necessary for informing the gun policy debate is woefully incomplete. Internet search patterns have the potential to serve as a valuable complementary information source to existing approaches.

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Gun violence is a major public health issue in the United States, responsible for tens of thousands of deaths annually. Even though gun control continues to be a major focus of public policy debate, the data necessary to inform this debate is woefully incomplete.  The current main source of information relating to gun purchases draws from the Federal Bureau of Investigation’s National Instant Criminal Background Check System (NICS). These mandatory background checks cover formal purchases at gun stores, but exclude the large number of guns purchased at gun shows or in private transactions. Without an accounting of these sales channels, the United States is veritably flying blind when it comes to gauging the overall demand for firearms.

We sought to examine the use of Internet search data as a potential complementary data source for informing the gun policy debate. Internet search data have the advantage of being freely available in near-real time at fine geographic resolutions, and have the potential to capture multiple types of gun transactions -- not just those taking place at official gun stores.

In our recent paper in npj Digital Medicine, we found a strong correlation between a range of key Internet search terms and gun background checks, gun deaths, and gun policies. We found that these correlations hold over both space and time, and that they are even stronger when stratified according to gun type (long guns vs. handguns).

Since submitting our paper for publication, these data have continued to fascinate. Looking at gun-related searches in 2020, we see significant spikes in search volumes for a number of key search terms (9mm, pistol, rifle, shotgun, ammo) around the time of the first wave of lockdowns in March, 2020, and a general increase since the election in early November, 2020 (Figure 1).

Figure 1 Relative Internet search volumes for gun-related search terms during the 12 months from December, 2019 to November, 2020. Search terms include: “9mm” (blue), “pistol” (red), “rifle” (yellow), “shotgun” (green), and “ammo” (violet). Spikes are seen during the first wave of lockdowns in mid-March, 2020 and following the elections in early November, 2020. (Source: Google Trends).

Looking more broadly at the last 5 years, the recent spikes in searches for “ammo” are very significant (Figure 2). These trends can give us a real time view of gun and ammunition purchases and provide a glimpse into the impact of external events such as pandemics and elections. The results can provide key metrics in informing highly impactful gun policy decisions.

Figure 2 Relative Internet search volumes for “ammo”  during the 5 years  from December, 2015 to November, 2020. A major spike is seen during the first wave of lockdowns in mid-March, 2020 and following the elections in early November, 2020. (Source: Google Trends).

We had previously studied whether Internet search data could be used to inform another major policy debate: abortion. There, we found an inverse relationship between reported abortion rates and Internet searches related to abortion - likely due to abortion-seeking individuals in states with restrictive polices using the Internet to search for out-of-state options.  Conversely, here we find a direct relationship between gun policy permissiveness and Internet searches related to guns: The more permissive the gun policies, the more Internet searches related to guns. One possible interpretation is that there is indeed higher demand for guns among the population of states with more permissive gun policies -- local policies reflect local preferences.

Gun policy is an important public policy debate with serious public health implications.  We call on policymakers to encourage and enable broader data collection from diverse information sources in order to inform this important public health debate. In the meantime, Internet search data can serve as a valuable complementary resource for tracking these vital societal trends.

Ben Reis

Director, Predictive Medicine Group, Harvard Medical School and Boston Children's Hospital