A graphical method for comparing trends in series of events

Abstract

This paper describes a new graphical method for comparing trends in two or more series of events. The method is applicable,e.g., to observations such as the successive times to failure of two or more devices and the arrival times on succeeding days at a service facility. The graphs provide information about the rela-tive trend and can be used to order several series with respect to rates of occurrence of events. The series are assumed independent of one another and are assumed to follow nonhomogeneous Poisson processes with mean functions and rate functions unspeci-fied.

Keywords:

• comparing trends
• convex composition
• ordering
• nonhomoqeneous poisson process
• relative trend