This thesis is concerned with the development of new methods for analyzing life and degradation data to improve product reliability. For this purpose, Taguchi's robust design procedure can be used to make product reliability insensitive to those factors that are hard or impossible to control. Sometimes, in order to obtain life or degradation data within a reasonable time, life or degradation tests must be conducted under stressed conditions, such as higher than normal temperature or humidity levels. An important concern in using the accelerated tests is how to ensure that the control factor levels found optimum during the accelerated tests will also be optimum under normal conditions. However, previous research, including Taguchi's, did not deal with the data obtained from these accelerated conditions. In this thesis new methods are developed for analyzing life and degradation data collected from the stressed conditions as well as the normal use conditions to achieve robust reliability.
