Early Detection Of Reliability Changes For A Non-Poisson Life Model Using Field Failure Data

This paper develops and validates a technique for identifying small changes in field reliability irrespective of how large the installed base of product is. Upper and lower limits are identified for monthly returns. This research applied the early detection procedure for a lognormal failure process although the technique described could equally be applied to other nonconstant failure rate processes. Actual field reliability data obtained over a two-year period is used to illustrate and validate the technique. The method also allows traceability back to specific months in which the product was manufactured. This allows the manufacturer to quickly recognize any improvement or deterioration in field reliability and identify how changes in production have affected field reliability.