This was a great article, but I'm not convinced mass shootings are completely independent. Given the media attention, it is very likely that event n+1 was, in some way, impacted by event n.
I don't have any evidence to back this up, so I could be (and I hope I am) completely wrong. But if I'm right, then I think it would imply we need to reduce the correlation between events. And it is likely the media that provides that correlation. Instead of reporting about the <insert your word here> that causes these events, report on the impacts of these events. It would, hopefully, stop deifying the perpetrator, which might reduce the likelihood of other perpetrators from doing the same.
There should be some way to formalize this into a hypothesis. Testable with the same data I mean. If you were correct we should see more clustering then we do with a random sample.
You'd get weird mixture model type systems. There are certain subclasses: school-based vs non-school-based. You'd have to control for this since school-based shootings are highly temporally correlated. But then maybe there's crossover too. Like everything, estimating these things with more complex models is hard to do right, and findings are usually overstated.
I don't have any evidence to back this up, so I could be (and I hope I am) completely wrong. But if I'm right, then I think it would imply we need to reduce the correlation between events. And it is likely the media that provides that correlation. Instead of reporting about the <insert your word here> that causes these events, report on the impacts of these events. It would, hopefully, stop deifying the perpetrator, which might reduce the likelihood of other perpetrators from doing the same.