ABSTRACT
Much of the theory of reliability deals with nonrepairable systems or devices, and it emphasizes the study of lifetime models. It is important to distinguish between models for repairable versus nonrepairable systems. A nonrepairable system can fail only once, and a lifetime model such as the Weibull distribution provides the distribution of the time at which such a system fails. On the other hand, a repairable system can be repaired and placed back in service. Thus, a model for repairable systems must allow for a whole sequence of repeated failures, and it must be capable of reflecting changes in the reliability of the system as it ages. As in the case of failure truncated data, it is possible with time truncated data to test for goodness-of-fit of the Weibull process by transforming to the exponential model. Any test of exponentiality with unknown mean and based on the order statistics will provide a goodness of fit test for the Weibull process.
