Keep in mind that overall shootings and murders are down, way down. Yet here is Michael Rosenwald:
In 1975, someone walking up the street shooting people was such an alien idea that one of the officers who responded didn’t believe it and hadn’t been trained for it. The phrase “active shooter” had yet to enter the cultural lexicon. Now mass shootings are so common that the assailants draw inspiration from one another, and the degrees of separation between victims appear to be closing.
The 1966 U. Texas incident is seen as one turning point, Columbine in 1999 another. The timing doesn’t exactly coincide with a social media hypothesis, although social media likely play a big role in the echo chamber and copycat effects. Is there an increase in fame-seeking behavior of all kinds?
What other testable predictions can we come up with? The frequency of the attacks is accelerating, again while violent crime and murder are largely falling.