Who was the infector { probabilities in the presence of individual variability

The probability that an observed infection has been transmitted from a particular member of a set of potential infectors is calculated. The calculations only use knowledge of the infection times. It is shown that the probabilities depend on the variability of individual infectivity. The analyses are based on dierent background information and dierent assumptions on the progress of infectivity. The results are illustrated by numerical calculations and simulations.