ESTIMATION OF PARAMETERS IN STEP-STRESS ACCELERATED LIFE TESTS FOR THE RAYLEIGH DISTRIBUTION UNDER CENSORING SETUP
Keywords:
Step-stress Accelerated Life Tests, Cumulative Exposure Model, Rayleigh Distribution, Maximum Likelihood Estimation, Type-I And Type II Censoring, Fisher Information Matrix, Bootstrap Confidence Interval.Abstract
In this paper, step-stress accelerated life test strategy is considered in obtaining the failure time data of the highly reliable items or units or equipment in a specified period of time. It is assumed that life time data of such items follows a Rayleigh distribution with a scale parameter (θ ) which is the log linear function of the stress levels. The maximum likelihood estimates (MLEs) of the scale parameters (θi) at both the stress levels (s ), i =1, 2 i are obtained under a cumulative exposure model. A simulation study is performed to assess the precision of the MLEs on the basis of mean square error (MSE) and relative absolute bias (RABias). The coverage probabilities of approximate and bootstrap confidence intervals for the parameters involved under both the censoring setup are numerically examined. In addition to this, asymptotic variance and covariance matrix of the estimators are also presented.
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