DOES THE NEGATIVE BINOMIAL-DISTRIBUTION ADD UP

The negative binomial distribution (NBD) is widely used to describe th e distribution of parasitic helminths in a number of host individuals and has proved a useful, though possibly overused, empirical and theor etical device! It is therefore important that the limits to the applic ability of the NBD be clearly defined. In this paper, Alan Grafen and Mark Woolhouse consider applications of the NBD in situations where ei ther the host or parasite population can be divided into subpopulation s of different types (eg. by age, sex or genotype), and they describe the relationships between the frequency distributions relevant to the different subpopulations and those relevant to the total population.