Reliability testing for non-constant MTBFs

The mean time between failures (MTBF) of new products has been found to increase with time due to the decreasing number of process problems and design problems found as test time is accumulated. The author's purpose is to show one method of considering this when developing a probability ratio sequential test plan (PRST). The method results in a shorter test time to an accept decision for a product with a high MTBF and a longer test time to a reject decision for a product with a low MTBF.<
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