ABSTRACT
This chapter explores the common ground of reliability measurement and prediction. Probabilistic reliability engineers use the constant failure rate portion of the bathtub curve for failure rate prediction in the scheduling of system maintenance, and for spare parts provisioning. The basic tool of the reliability engineer is the life distribution, which may be also called the failure distribution. Life distributions are mathematical descriptions of failures in time. They can be either probabilistic or deterministic. Both deterministic and probabilistic reliability professionals are interested in methods to measure and predict failures, although they may use them in different ways. The most commonly used forms of life distribution are the probability density function, the cumulative density function, the reliability function, and the hazard rate. Life distributions can have any shape, but some standard forms have been developed over the years, and reliability engineers generally try to fit their data to one of them so that conclusions can be drawn.
