A branching process starting with a single individual. At the end of that individual's life it gives rise to n further individuals. All the individuals have the same lifetime distribution and n is an observation from a specified probability distribution. The question of interest is the number of individuals in existence at a given timepoint. The process was introduced by Bellman and Harris in 1952 and has been used in biology to model the growth of populations and the spread of epidemics.
Subjects: Probability and Statistics.