Check out this provocative open-access paper titled Contagion in Mass Killings and School Shootings (Towers, et al., 2015). Here is an extended excerpt (footnotes omitted): “We fit a mathematical contagion model to the data sets, with model terms that take into account temporal trends due to possible exogenous non-contagion factors, and a contagion term that takes into account the fact that a school shooting or mass murder may temporarily increase the probability of a similar event in the immediate future. We model the contagion process assuming an exponential decay in contagiousness after an event. Contagion models have been applied to financial markets, spread of YouTube videos on social networks, burglary, civilian deaths in Iraq, and terrorist attacks, but this is the first instance in which these models have been applied in the context of mass murders and school shootings.” Hat tip: Tyler Cowen, via Marginal Revolution.

Credit: Towers, et al.