Another look at life testing

In life testing, n identical testing items are placed on test. Instead of doing a complete life testing with all n outcomes, a Type II censored life testing, consisting of the first m outcomes, is usually employed. Although statistical analysis for the life testing based on censored data is less efficient than the complete life testing, the expected length of the censored life testing is less than that of the complete life testing. In this paper, we compare censored and complete life testing and suggest ways to improve time saving and efficiency. Instead of doing a complete life testing with all n outcomes, we put N>n items on test, which continues until we observe the nth outcome. With both the censored life testing and the complete life testing containing the same number of observations, we show that the expected length of the censored life testing is less than that of the complete life testing and that the censored life testing may be also more efficient than the complete life testing with the same number of observations.