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arXiv 1709.08720stat.CO
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随机截尾情形下的极值指数估计

On Extreme Value Index Estimation under Random Censoring

Richard Minkah, Tertius de Wet, Kwabena Doku-Amponsah

摘要:

删失条件下的极值分析在许多学科中得到了广泛的应用,包括生存和可靠性研究。极端值指数(EVI)的估计是最重要的,因为它是估计极端事件(如分位数和重复概率)所需的关键参数。本文综述了随机截尾数据下极值指标的几种估计。此外,提出了四个估计,一个基于对数间距的指数回归近似,一个基于Zipf估计和两个基于矩估计的变体。在相同的仿真条件下,对所提出的估计器和现有的估计器进行了比较。估计量的性能度量包括置信区间长度和覆盖概率。模拟结果表明,没有估计是普遍最好的估计依赖于EVI参数的大小,截尾的右尾和潜在的分布的百分比。然而,某些估计,如建议的减少偏差估计和自适应矩估计被发现在大多数情况下表现良好。此外,我们提出了一个bootstrap算法,用于在删失情况下获得极值分析的样本。一些在模拟研究中表现良好的估计器使用来自医学研究的实际数据集进行说明

英文摘要:

Extreme value analysis in the presence of censoring is receiving much attention as it has applications in many disciplines, including survival and reliability studies. Estimation of extreme value index (EVI) is of primary importance as it is a critical parameter needed in estimating extreme events such as quantiles and exceedance probabilities. In this paper, we review several estimators of the extreme value index when data is subject to random censoring. In addition, four estimators are proposed, one based on the exponential regression approximation of log spacings, one based on a Zipf estimator and two based on variants of the moment estimator. The proposed estimators and the existing ones are compared under the same simulation conditions. The performance measures for the estimators include confidence interval length and coverage probability. The simulation results show that no estimator is universally the best as the estimators depend on the size of the EVI parameter, percentage of censoring in the right tail and the underlying distribution. However, certain estimators such as the proposed reduced-bias estimator and the adapted moment estimator are found to perform well across most scenarios. Moreover, we present a bootstrap algorithm for obtaining samples for extreme value analysis in the context of censoring. Some of the estimators that performed well in the simulation study are illustrated using a practical dataset from medical research

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