weak dependence

弱依赖性
  • 文章类型: Journal Article
    多重检验一直是统计研究中的一个突出课题。尽管在这方面做了大量的工作,控制错误发现仍然是一项具有挑战性的任务,特别是当检验统计量表现出依赖性时。已经提出了各种方法来估计在测试统计量之间的任意依赖性下的错误发现比例(FDP)。一种关键方法是将任意依赖转化为弱依赖,并随后建立FDP的强一致性和弱依赖下的错误发现率。因此,FDP在弱依赖框架内收敛到相同的渐近极限。然而,我们已经观察到,FDP的渐近方差可以显著影响的依赖结构的检验统计,即使它们只表现出微弱的依赖性。量化这种可变性具有非常重要的实际意义,因为它可以作为从数据中评估FDP质量的指标。据我们所知,文献中对这方面的研究有限。在本文中,我们的目标是通过量化FDP的变化来填补这一空白,假设检验统计量表现出弱依赖性,服从正态分布。我们首先推导FDP的渐近展开,然后研究FDP的渐近方差如何受到不同依赖结构的影响。基于从这项研究中获得的见解,我们建议在使用FDP的多个测试程序中,报告FDP的均值和方差估计值可以为研究结果提供更全面的评估.
    Multiple testing has been a prominent topic in statistical research. Despite extensive work in this area, controlling false discoveries remains a challenging task, especially when the test statistics exhibit dependence. Various methods have been proposed to estimate the false discovery proportion (FDP) under arbitrary dependencies among the test statistics. One key approach is to transform arbitrary dependence into weak dependence and subsequently establish the strong consistency of FDP and false discovery rate under weak dependence. As a result, FDPs converge to the same asymptotic limit within the framework of weak dependence. However, we have observed that the asymptotic variance of FDP can be significantly influenced by the dependence structure of the test statistics, even when they exhibit only weak dependence. Quantifying this variability is of great practical importance, as it serves as an indicator of the quality of FDP estimation from the data. To the best of our knowledge, there is limited research on this aspect in the literature. In this paper, we aim to fill in this gap by quantifying the variation of FDP, assuming that the test statistics exhibit weak dependence and follow normal distributions. We begin by deriving the asymptotic expansion of the FDP and subsequently investigate how the asymptotic variance of the FDP is influenced by different dependence structures. Based on the insights gained from this study, we recommend that in multiple testing procedures utilizing FDP, reporting both the mean and variance estimates of FDP can provide a more comprehensive assessment of the study\'s outcomes.
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  • 文章类型: Journal Article
    变化点是观察或数据遵循两个不同模型的位置或时间:前后。在真正的问题中,我们可能知道一些关于变化点位置的先验信息,在序列的右边或左边。如何将先验信息纳入当前累积和(CUSUM)统计量?我们提出了一类新的加权CUSUM统计量,具有三种不同类型的二次权重,可考虑变化点的不同先验位置。权重的一种解释是随机游走中的平均持续时间。在已知方差的正态模型下,这些统计数据的确切分布明确表示为特征值。关于分布的显式差异的理论结果是有价值的。将渐近分布的扩展与Cramér-vonMises统计量以及Anderson和Darling统计量的极限分布的扩展进行了比较。我们提供了从独立正态响应到更有趣模型的一些扩展,如图形模型,法线的混合物,Poisson,和弱依赖模型。仿真表明,所提出的测试统计信息比基于图的统计信息具有更好的功能。我们说明了它们在视频数据检测问题中的应用。
    A change point is a location or time at which observations or data obey two different models: before and after. In real problems, we may know some prior information about the location of the change point, say at the right or left tail of the sequence. How does one incorporate the prior information into the current cumulative sum (CUSUM) statistics? We propose a new class of weighted CUSUM statistics with three different types of quadratic weights accounting for different prior positions of the change points. One interpretation of the weights is the mean duration in a random walk. Under the normal model with known variance, the exact distributions of these statistics are explicitly expressed in terms of eigenvalues. Theoretical results about the explicit difference of the distributions are valuable. The expansions of asymptotic distributions are compared with the expansion of the limit distributions of the Cramér-von Mises statistic and the Anderson and Darling statistic. We provide some extensions from independent normal responses to more interesting models, such as graphical models, the mixture of normals, Poisson, and weakly dependent models. Simulations suggest that the proposed test statistics have better power than the graph-based statistics. We illustrate their application to a detection problem with video data.
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  • 文章类型: Journal Article
    Dependent phenomena, such as relational, spatial and temporal phenomena, tend to be characterized by local dependence in the sense that units which are close in a well-defined sense are dependent. In contrast with spatial and temporal phenomena, though, relational phenomena tend to lack a natural neighbourhood structure in the sense that it is unknown which units are close and thus dependent. Owing to the challenge of characterizing local dependence and constructing random graph models with local dependence, many conventional exponential family random graph models induce strong dependence and are not amenable to statistical inference. We take first steps to characterize local dependence in random graph models, inspired by the notion of finite neighbourhoods in spatial statistics and M-dependence in time series, and we show that local dependence endows random graph models with desirable properties which make them amenable to statistical inference. We show that random graph models with local dependence satisfy a natural domain consistency condition which every model should satisfy, but conventional exponential family random graph models do not satisfy. In addition, we establish a central limit theorem for random graph models with local dependence, which suggests that random graph models with local dependence are amenable to statistical inference. We discuss how random graph models with local dependence can be constructed by exploiting either observed or unobserved neighbourhood structure. In the absence of observed neighbourhood structure, we take a Bayesian view and express the uncertainty about the neighbourhood structure by specifying a prior on a set of suitable neighbourhood structures. We present simulation results and applications to two real world networks with \'ground truth\'.
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