Past exam of the mathematics course of the University of Cambridge / 2017 / iii / Paper 207 / 3 / c / i / Solution

For a treated patient the recovery transition intensity is ${\mu }_T=0.25\times 2=0.5$ per year. A symptoms spell is a holding time with an exponential distribution of rate ${\mu }_T$, soThe treatment multiplier for onset affects how often symptoms begin, not the duration of a spell once the patient is in state 2, under this homogeneous continuous-time Markov chain.