Article ID Journal Published Year Pages File Type
1150026 Journal of Statistical Planning and Inference 2007 12 Pages PDF
Abstract

For exponentially distributed failure times under general progressive censoring schemes, testing procedures for ordered failure rates are proposed using the likelihood ratio principle. Constrained maximum likelihood estimators of the failure rates are found. The asymptotic distributions of the test statistics are shown to be mixtures of chi-square distributions. When testing the equality of the failure rates, a simulation study shows that the proposed test with restricted alternative has improved power over the usual chi-square statistic with an unrestricted alternative. The proposed methods are illustrated using data of survival times of patients with squamous carcinoma of the oropharynx.

Related Topics
Physical Sciences and Engineering Mathematics Applied Mathematics
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