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arXiv 2209.05795stat.ME
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双变量数据的主体与尾部联合建模

Joint modelling of the body and tail of bivariate data

Lídia M. André, Jennifer L. Wadsworth, Adrian O'Hagan

AI总结:

针对双变量场景下同时刻画数据主体与尾部依赖的模型稀缺问题,提出一种结合两类copula与动态加权函数的混合依赖模型,经数值分析、模拟及英国气温-臭氧数据验证,拟合效果更优且能捕捉复杂依赖结构。

摘要:

在极端数据与非极端数据均受关注的场景中,对整个数据集进行准确建模十分重要。在单变量框架下,分布的主体(bulk)与尾部建模此前已得到广泛研究。但当涉及多个变量时,文献中专门针对同时准确刻画这两个区域的模型仍较为稀缺。本文提出一种依赖模型,该模型在数据支撑集的整个范围内混合两种具有不同特征的copula(连接函数):一种copula适配主体区域,另一种适配尾部区域,并采用动态加权函数实现二者之间的平滑过渡。研究通过数值方法分析了尾部依赖特性,并借助模拟实验验证了该混合模型具备足够灵活性,能够捕捉多种多样的依赖结构。研究将该模型应用于英国两个站点的气温与臭氧浓度之间的依赖关系研究,并与单一copula拟合结果进行对比。结果表明,所提出的模型对数据的拟合效果更优、灵活性更强,且能够捕捉复杂的依赖结构。

英文摘要:

In situations where both extreme and non-extreme data are of interest, modelling the whole data set accurately is important. In a univariate framework, modelling the bulk and tail of a distribution has been extensively studied before. However, when more than one variable is of concern, models that aim specifically at capturing both regions correctly are scarce in the literature. A dependence model that blends two copulas with different characteristics over the whole range of the data support is proposed. One copula is tailored to the bulk and the other to the tail, with a dynamic weighting function employed to transition smoothly between them. Tail dependence properties are investigated numerically and simulation is used to confirm that the blended model is sufficiently flexible to capture a wide variety of structures. The model is applied to study the dependence between temperature and ozone concentration at two sites in the UK and compared with a single copula fit. The proposed model provides a better, more flexible, fit to the data, and is also capable of capturing complex dependence structures.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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