Power Law & The Hawkes Process

Scientists have been using a mathematical model called the Hawkes Process to study terrorist attacks. The concept is a Power Law, i.e. it assesses the relationship between two quantities wherein a change in one quantity results in a proportional relative change in the other. The idea is that terror attacks don’t always occur independently. More often than not, a major attack boosts the likelihood of a follow-up terror attack. However, the chances of a repeat attack keep diminishing with time.