Interparticle correlation in death processes with application to variability in compartmental models

This paper is concerned with a pure death process, starting with N individuals, with death rates μ n , n = 1, 2, …, N. It is shown that the fates of distinct individuals are positively correlated if μ n /n decreases with n, and negatively correlated if μ n /n increases with n. The application of this result to the problem of variability in compartmental models is elaborated and in particular a conjecture of Faddy (1985) is settled. Further applications to well-known death processes are also briefly described.