Trends in Mass Shootings

Right-wing ideologue S.E. Cupp recently challenged left-wing ideologue Michael Moore,

Mass shootings are also down... yes they are! It is true! Mass shootings are... It is fact! They are down, as is gun crime. That's a fact.... Look it up, I'm not the first person who said it.

Well, facts are important, but they're not something I find to strongly correlate with Cupp's arguments. So let's take a look. If you apply a narrow definition that excludes "things like armed robbery or gang violence", as did Mother Jones, you find an increase in casualties and that "24 of the last 62 worst mass shootings have taken place in the past seven years alone". If you apply a broad definition, Fox News found that mass shootings are holding steady.

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.

I would wonder what Cupp was looking at, but she seems like the type who believes that anything she says magically becomes true if she argues forcefully or claims "It's a fact!"

When Moore challenged her, specifically in relation to school shootings, Cupp added to (or is it amended) her claim,

There have been fewer mass shootings over the past thirty years. That's just a fact.

It's certainly not a fact in relation to school shootings. I have not yet found data predating 1976, but it's also not true in relation to homicides with multiple victims going back to 1976. Perhaps she's alluding to lynchings and prohibition-era violence associated with organized crime? One can only guess - but when you're addressing a relatively rare type of crime (homicide with multiple victims) such factors can easily skew the trend.

At this point, I'm comfortable concluding that Cupp was either making stuff up or was cherry-picking a source in order to present what she knows to be a distorted, fundamentally untrue statement of "fact". I'm prepared to be proved wrong. Anybody?