First, the timing of attacks in each conflict proved to be remarkably similar. Rather than occurring randomly, they came in a characteristic “bursty” distribution over time; days of extreme violence were clustered as well. This would be easy to explain if the attacks were coordinated–as they are in traditional command-and-control warfare–but in these conflicts, insurgent groups were acting largely independent of one another, without direct communication.
Even stranger, the distribution of violence within each conflict closely followed a power law, a relationship between two quantities often seen in physical phenomena such as metabolic rates and earthquakes. For example, the power law distribution of earthquakes allows scientists to predict the likelihood of an earthquake of a given magnitude over a given time period. Similarly, a power law seems to determine the chance of a terrorist attack of any given magnitude: such as 10, 100, or 1000 deaths