The White and Pagano (WP) estimator uses maximum likelihood estimation to estimate <em>R</em><sub>0</sub>.
In this method, the serial interval (SI) is either known, or can be estimated along with <em>R</em><sub>0</sub>.
It is assumed that the number of infectious individuals are observable at discrete time points (ie. daily or weekly).
Further, this method also assumes an underlying branching process, which means that throughout, the population size “available” to be infected remains constant.
We note that this assumption does not hold for the SIR/SEIR/SEAIR compartmental models.
As such, WP estimates should only really be considered early on in an epidemic, ie. before the inflection point of an epidemic, if the dataset being used follows these models.