New research from the Harvard School of Public Health “demonstrates that mass shootings in public have become far more frequent. The Harvard findings are also corroborated by a separate report issued recently by the FBI,” according to a Mother Jones report.

Instead of simply finding the yearly number of mass shootings in this country, Harvard researchers Amy Cohen, Deborah Azrael, and Matthew Miller determined that their frequency is best measured by keeping track of the time between each incident.

“This method, they explain, is most effective for detecting meaningful shifts in relatively small sets of data, such as the 69 mass shootings we documented,” writes Mark Follman. “Their analysis of the data shows that from 1982 to 2011, mass shootings occurred every 200 days on average. Since late 2011, they found, mass shootings have occurred at triple that rate—every 64 days on average.”

A clear, universally accepted definition of “mass shooting” does not exist. But data collected by the FBI on “active shooter incidents” is nearly identical to that which Mother Jones collected. “That the results of the two studies are so similar,” the Harvard researchers say, “reinforces our finding that public mass shootings have increased.”

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