1. A method of analysing a process, the method comprising: generating a process template; determining a probabilistic model of the process, the probabilistic model specifying the process template, wherein the probabilistic model comprises: a plurality of task nodes, the task nodes being nodes for tasks of the process as specified by the process template; a plurality of observables nodes, the observables nodes being nodes for observables that may be caused by performance of the tasks; and a background activities node; wherein one or more of the observables may further be caused by background activities of the background node; measuring values of an observable corresponding to one of the observables nodes; and updating a probabilistic estimate of a process state using the measured values.