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Graph of the day: Perhaps mass shootings aren’t becoming more common

Last Friday, I wrote a post noting that mass shootings appeared to be on the upswing in the United States — even as other types of crimes were going down. I was largely relying on data from this Mother Jones investigation finding an uptick in mass shooting casualties since 1982:

And it wasn't just casualties. Mother Jones found that 24 of the last 62 worst mass shootings have taken place in the past seven years alone. That seemed like a clear increase.

But is this the right way of looking at things? Over at Reason, Jesse Walker criticizes my post and points to data from James Allan Fox, a criminologist at Northeastern, who has found that there's been no discernible increase in mass shootings since 1980:

Why the difference? Fox is looking at all mass shootings involving four or more victims — that's the standard FBI definition. Mother Jones, by contrast, had a much more restrictive definition, excluding things like armed robbery or gang violence. They were trying to focus on spree killings that were similar in style to Virginia Tech or Aurora or Newtown. The definitions make a big difference: On Fox's criteria, there's no uptick. On Mother Jones', there's a clear increase.

Meanwhile, by either criteria, there does seem to be a surge in mass shootings in 2012. But it's unclear whether that's a one-year blip or not.

So, duly noted. One final point, though: Even if mass shootings are simply staying constant, and not actually increasing, that might still be of interest given that the overall rate of gun violence and homicide in the United States appears to be on the downswing.