title: Effect of a guarantee time on sample size determination for testing the ratio of means from two lifetime distributions.
abstract: This paper studies the problem of sample size determination for testing the ratio of means from two lifetime distributions when thresholds, or guarantee times, are present in the survival distributions. We consider several different approaches of sample size determination based on different distributional assumptions and discuss the role that guarantee times play in these sample size computations. We show that the guarantee times, if they exist, can significantly affect the sample size computations. The Aging Intervention Testing Program from the National Institute on Aging is used to demonstrate our results.
authors.affiliation: Division of Biostatistics, Washington University in St. Louis, St. Louis, Missouri 63110, USA. chengjie@wubios.wustl.edu
authors.forename: Chengjie
authors.initials: C
authors.lastname: Xiong
authors.forename: J Philip
authors.initials: JP
authors.lastname: Miller
authors.forename: Yan
authors.initials: Y
authors.lastname: Yan
authors.forename: Ming
authors.initials: M
authors.lastname: Ji
mesh_terms: D002986:Clinical Trials as Topic / Q000379:methods / Q000706:statistics & numerical data*; D006801:Humans; D018401:Sample Size; D013997:Time Factors