title: Sample size calculation for the van Elteren test adjusting for ties.
abstract: In this article we study sample size calculation methods for the asymptotic van Elteren test. Because the existing methods are only applicable to continuous data without ties, in this article we develop a new method that can be used on ordinal data. The new method has a closed form formula and is very easy to calculate. The new sample size formula performs very well because our simulations show that the corresponding actual powers are close to the nominal powers.
authors.affiliation: Lilly Research Laboratories, Eli Lilly and Company, Indianapolis, Indiana 46285, USA. yzhao@lilly.com
authors.forename: Yan D
authors.initials: YD
authors.lastname: Zhao
authors.forename: Dewi
authors.initials: D
authors.lastname: Rahardja
authors.forename: Yajun
authors.initials: Y
authors.lastname: Mei
mesh_terms: D002986:Clinical Trials as Topic / Q000706:statistics & numerical data*; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D006801:Humans; D015233:Models, Statistical; D015203:Reproducibility of Results; D018401:Sample Size; D018709:Statistics, Nonparametric; D016896:Treatment Outcome