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This paper is concerned about the concept os asymmetry. The different types of asymmetry for univariate and multivariate distributions have introduces been considered as well as some of usual asymmetry criteria. A brief overview of method for adding the capability of modeling asymmetry to a symmetry distribution is also a secondary purpose of this paper.

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In this article introduce the sequential order statistics. Therefore based on multiply Type-II censored sample of sequential order statistics, Bayesian estimators are derived for the parameters of one- and two- parameter exponential distributions under the assumption that the prior distribution is given by an inverse gamma distribution and the Bayes estimator with respect to squared error loss is calculated. Moreover, prediction of future failure time is considered. Finally in example Bayesian estimator and non-bayesian estimatores, namely the Best Linear Unbiased Estimator (BLUE) and Approximate Maximum Likelihood Estimator (AMLE) are derived.