where P max is the probability of a visit for the eight groups directly neighbouring the hotspot, and R is the hotspot radius of attraction. Groups occupying cells that are farther from the hotspot than R never visit it. When a group visits the hotspot, it follows a Biased Random Walk from its home cell to the hotspot (BRW [25] ) and returns to its home cell on the same day. The length of each step of the BRW (denoted S) is held constant and the direction of the step is consistently biased towards the hotspot during the approach to the hotspot and towards the group's home cell during the return from the hotspot. Each turning angle is randomly drawn from a normal distribution N (0, s 2 ), where s is a standard deviation parameter. The list of groups residing in cells encountered along each BRW to the hotspot is recorded. Groups travel to the hotspot and come back within a single time step.