How Frequent Are Mass Shootings?

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A reader writes:

During your participation in last night’s AC360 Later, Emily Miller took issue with Anne-Marie Slaughter when she said there have been mass shootings “every couple of months” since Newtown, to which Miller countered strongly by saying that was not factual.

Here are the facts. According to an investigation by Emily Thomas (published yesterday, coincidentally), there have been “at least” 17 mass shootings in 2013 alone [defined by the FBI standard of four victims or more]. So not only is it factually accurate to say there have been mass shootings “every couple of months”, it’s factually MORE accurate to say there have been mass shootings every couple of weeks. In fact, Monday’s tragic Navy Yard shooting was the second mass shooting in September alone, and the month’s not even over. So, as a matter of fact, Anne-Marie was right and Emily was wrong. Chilling graphic here.

Paul Campos looks at a different standard over a longer period of time:

[Looking at shootings in which at least 14 victims died], it turns out that the rate of this type of mass shooting in America was nearly twice as high in the 25 years between 1966 and 1991 as it has been in the 22 years since (there were four such shootings in the former period, and two in the latter). Or we could use the FBI’s definition of a mass shooting: one in which at least four people, not including the perpetrator, are killed. This is a vastly larger category … : there were about 600 such incidents in the United States between 1980 and 2010.  As James Alan Fox, a professor of criminology at Northeastern University points out, the rate of such mass shootings does not appear to be rising

Another reader comments on a related post:

I agree with most of what Frum says about some moderate gun regulations based on personal behavior, but then he crosses into crazy land, both in terms of policy and politics. There are approximately 16,000 homicides each year in the US, 11,000 involving a gun.  How many of those deaths are the result of mass shootings?  Less than 100*. So when Frum says, “The classes of weapons associated with mass casualty shooting could be more strictly controlled,” he is basing a policy decision on a class of homicide that represent only .625% of all homicides.

In my class on risk assessment 20 years ago, this would be called example bias.  Mass shootings are traumatic, random events with huge media coverage that also happen to be very rare when compared to boring, and common, shootings related to criminal activities.  People will incorrectly claim that more people die in fires than in drownings for the same reason – the media covers fires because they are visual, and most people find dying in a fire more horrific than drowning.  Mass shootings are an edge case.  I would be fired as an engineer if I had a large problem to solve and I spent time obsessing on an edge case.

From a political point of view, spending time on the modern sporting rifle ban (technically they are not assault rifles because they cannot fire in fully automatic) is a bad idea not only because the votes do not exist but because the slippery slope arguments stops being crazy if the opposition walks up to the line and leans as far over that line as they can without crossing it.  Banning a gun is as close as you can get to taking guns as you can get.  Nothing riles up the pro-gun base more than the thought of people taking their guns, so even mentioning a ban is close enough to confiscation that you might as well be saying that you will take their guns.

So a word of advice for the gun-control crowd: never mention a gun ban again if you want to pass something like universal background checks that have a chance of actually saving a significant number of lives.  It ain’t gonna happen, and it will likely torpedo any chance of getting any other gun regulation.

*The FBI defines a mass shooting as one involving 4 or more deaths, committed within a 24hr period at a single location not related to criminal activity.  2012 was an exceptional year for mass shootings and exceeded 100, but generally it’s less than 100.

The above map by Jan Diehm is also based on that FBI standard for mass shootings.