Friday, December 28, 2012

Statistical bias from specification error

ANN COULTER: We know how to stop school shootings | The Daily Caller:

Coulter takes on a study of mass shootings carried out by Mother Jones Magazine that claims to demonstrate that armed citizens never stop mass shootings. The reason, as Coulter makes clear, is that the study's definition of a mass shooting is one that excludes any mass shooting that was successfully stopped by an armed citizen (or armed anyone, for that matter). The Mother Jones study defines mass shootings as cases where four or more people were killed. As it turns out, there are several cases where the assailant clearing intended to kill large numbers of people but was successfully stopped by armed citizens, often merely by pointing the gun at the perpetrator.

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