A temporal Hawkes process model for shooting occurrences in Sweden

Sammanfattning: The Hawkes process, also referred to as a self-exciting point process, is a class of point processes where the intensity is conditioned on previous events. More specifically, an event occurrence excites the process, temporarily increasing the probability of more events occurring. One application of Hawkes processes is to model occurrences of crimes, such as burglaries or shootings. The present thesis attempts to apply the theory of Hawkes processes to shooting occurrences in Sweden, by exploring whether a temporal Hawkes process model is suitable to model shooting occurrences in the Police regions of Stockholm, V¨ast (West) and Syd (South). The results indicate that although there is reason to believe that shooting occurrences in the regions exhibit self-exciting tendencies, a temporal Hawkes process model with time invariant parameters is not adequate. The present thesis suggests that the reason for this lie in the parameters not being constant over time. Furthermore, based on previous research it is likely that a spatial component is needed to adequately capture the underlying process.