A recent mathematical development in maintenance theory

This paper introduces the mathematics of delay-time analysis and places it in context. Both the nature of and the scope for delay-time models are indicated, and example prototype models developed in the context of inspection policies. The essential role of subjective estimation is indicated, and the need to consider revisions of both the prior delay-time distribution and the delay-time model highlighted. An unavoidable bias that arises when estimating delay-time is discussed and the appropriate distribution of biased estimates deirved. A mechanism for correcting this bias when estimating a delay-time distribution is proposed, based upon maximum-likelihood considerations. Finally, general comments are made concerning other developments and applications of the technique.