Of targets and supertargets: A routine activity theory of high crime rates

Empirical work has shown that high crime areas have disproportionate amounts of repeat victimisation. However, there is inadequate theoretical explanation. As a move towards a theory we consider a mathematical model of crime rates grounded in routine activity theory. Using the binomial distribution, victimisation is measured as a series of Bernoulli trials, with crime measured for each of incidence (crimes per capita), prevalence (victims per capita), and concentration (crimes per victim). The model is then revised so that a proportion of targets progress to become chronically victimised 'supertargets'. The notion of supertargets is introduced to refer to the 3 or 4 percent of chronically victimised targets that account for around 40 percent of victimisation. We demonstrate theory-testing relating to crime requires the inclusion of the crime concentration rate to incorporate repeat victimisation and indicate how mathematical modelling may, in turn, illuminate the crime concentration predictions of routine activity theory.