ABSTRACT
The main purpose of fitting a chain binomial model to size of outbreak data is to gain insight into the nature of disease spread. The binomial distributions in chain binomial epidemic models arise as a result of the underlying assumption that each of the exposures which arise during the course of the epidemic chain is an independent Bernoulli trial, whose outcome is either infection or escape from infection. The chain binomial model assumes its simplest form when all individuals are equally susceptible and infected individuals reach the same level of infectiousness as well as remaining infectious for the same duration of time. Infectious disease data are observational data, rather than data from planned experiments. There are difficulties with the classification of cases of the common cold into generations, because the latent period for the common cold tends to be shorter than its infectious period.
