Determining the optimal spatial scan of Prospective space-time scan statistics (PSTSS) for crime hotspot prediction

The input value for the maximum spatial scan extent (K) of a prospective space-time scan statistical (PSTSS) technique is one important parameter that ensures accurate detection of the predictive hotspot of a geographical point events. Currently, there is no general consensus on how to determine the optimal value of K that maximises the predictive accuracy, especially in crime hotspot prediction. To address this issue, this study proposes a strategy in which different values of K are used to generate accuracy profiles that can be compared to determine optimal value of K. A case study presented shows that the best accuracy is obtained at K=250m, which is equivalent to the spatial aggregation of the crime dataset used. It is contended that this strategy could be extended to other geographical surveillance tasks.