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arXiv 1005.3573stat.AP
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极端Value Distributions中分位数的特征似然区间

Profile Likelihood Intervals for Quantiles in Extreme Value Distributions

A. Bolívar, E. Díaz-Francés, J. Ortega, E. Vilchis

摘要:

极值分布中大分位数的剖面似然区间提供了一种很好的方法来估计这些感兴趣的参数,因为它们考虑了在小样本量和中等样本量样本量的情况下似然曲面的不对称性;然而,它们在实践中很少使用。相反,通常使用极大似然渐近(mla)区间,而不考虑样本量。它在这里示出的配置文件似然区间实际上是一个很好的替代估计的分位数的样本量$25 \leq n\leq 100$的块最大值,因为他们提出了足够的覆盖频率相比,这些样本量,这也往往低估了分位数,因此可能是一个危险的统计实践的MLA区间的覆盖频率差。此外,极大似然估计可以呈现问题时,威布尔模型被认为是中等或小的样本量,由于奇异性的相应的密度函数时,形状参数小于1。这些估计问题可以追溯到常用的连续近似的似然函数,并可以避免使用精确或正确的似然函数,至少在这里考虑的设置。最后,以一个降雨资料为例,验证了本文提出的基于剖面似然分析的推理方法。

英文摘要:

Profile likelihood intervals of large quantiles in Extreme Value distributions provide a good way to estimate these parameters of interest since they take into account the asymmetry of the likelihood surface in the case of small and moderate sample sizes; however they are seldom used in practice. In contrast, maximum likelihood asymptotic (mla) intervals are commonly used without respect to sample size. It is shown here that profile likelihood intervals actually are a good alternative for the estimation of quantiles for sample sizes $25 \leq n\leq 100$ of block maxima, since they presented adequate coverage frequencies in contrast to the poor coverage frequencies of mla intervals for these sample sizes, which also tended to underestimate the quantile and therefore might be a dangerous statistical practice. In addition, maximum likelihood estimation can present problems when Weibull models are considered for moderate or small sample sizes due to singularities of the corresponding density function when the shape parameter is smaller than one. These estimation problems can be traced to the commonly used continuous approximation to the likelihood function and could be avoided by using the exact or correct likelihood function, at least for the settings considered here. A rainfall data example is presented to exemplify the suggested inferential procedure based on the analyses of profile likelihoods.

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