Sample sizes for comparing means of two lifetime distributions with type II censored data: Application in an aging intervention study

Sample size determination is a very important part of planning for clinical trials. Most clinical trials do not follow all their subjects to the terminal event, resulting in censored observations. This article presents a method of computing sample sizes required to achieve adequate statistical power to compare the means of two lifetime distributions when both samples are subject to type II censoring. Our approach is based on the location-scale family of log-transformed lifetime distributions as compared to that based on the log-rank test and the family of proportional hazards. Specific applications to log-normal distribution and Weibull distribution are also discussed.