title: Comparing survival curves based on medians.
abstract: BACKGROUND
  Although some nonparametric methods have been proposed in the literature to test for the equality of median survival times for censored data in medical research, in general they have inflated type I error rates, which make their use limited in practice, especially when the sample sizes are small.
  
  
  METHODS
  In this paper, we propose a new nonparametric test with a simple test statistic to compare median survival times.
  
  
  RESULTS
  The results from our comprehensive simulation study show the new test controls type I error rate very well under all situations considered, even for small sample sizes. In addition, it has comparable detecting power compared to existing methods. Another advantage of the proposed test is its relatively simple formula that requires less computation.
  
  
  CONCLUSIONS
  We propose a new statistical method for comparing survival curves based on their medians. The new method can be easily implemented and applied to censored event time data.
authors.affiliation: Department of Epidemiology and Biostatistics, School of Public Health, Indiana University Bloomington, 1025 E. 7th street, SPH C104, Bloomington, IN, 47405, USA. zc3@indiana.edu.
authors.forename: Zhongxue
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Department of Mathematics and Statistics, University of New Mexico, Albuquerque, NM, 87131, USA.
authors.forename: Guoyi
authors.initials: G
authors.lastname: Zhang
mesh_terms: D001699:Biometry / Q000379:methods*; D003198:Computer Simulation; D005260:Female; D006801:Humans; D053208:Kaplan-Meier Estimate; D008297:Male; D015233:Models, Statistical; D018401:Sample Size; D012680:Sensitivity and Specificity; D016019:Survival Analysis; D013997:Time Factors
keywords: Censored data; Cochran test; Nonparametric test; Survival analysis