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Journal of Applied Mathematics
Volume 2013 (2013), Article ID 273954, 8 pages
http://dx.doi.org/10.1155/2013/273954
Research Article

Weighted Wilcoxon-Type Rank Test for Interval Censored Data

1Department of Applied Mathematics, National Sun Yat-sen University, Kaohsiung 80424, Taiwan
2Center for Fundamental Sciences, Kaohsiung Medical University, Kaohsiung 80708, Taiwan
3Graduate School of Human Sexuality, Shu-Te University, Kaohsiung 82445, Taiwan

Received 8 November 2012; Accepted 19 December 2012

Academic Editor: Jen Chih Yao

Copyright © 2013 Ching-fu Shen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

Interval censored (IC) failure time data are often observed in medical follow-up studies and clinical trials where subjects can only be followed periodically, and the failure time can only be known to lie in an interval. In this paper, we propose a weighted Wilcoxon-type rank test for the problem of comparing two IC samples. Under a very general sampling technique developed by Fay (1999), the mean and variance of the test statistics under the null hypothesis can be derived. Through simulation studies, we find that the performance of the proposed test is better than that of the two existing Wilcoxon-type rank tests proposed by Mantel (1967) and R. Peto and J. Peto (1972). The proposed test is illustrated by means of an example involving patients in AIDS cohort studies.