A Method of Determining a Confidence Interval for Availability

摘要

This report presents a method of determining a confidence interval for availability when it is estimated from the mean time between equipment failures and the mean time to repair these failures. When the failure rate and repair rate of a system are constants independent of time, it can be shown that the estimates of mean time between failures and of mean time to repair the failures can be combined to have the variance ratio density. The estimated availability can be shown to have a density which is a function of the variance ratio density. This relation can then be used to obtain equations for a confidence interval for availability. An example is included to demonstrate the procedure of placing a confidence interval about the estimated availability. (Author)