simultaneous inference

  • 文章类型: Journal Article
    最近已证明封闭测试对于同时进行真实发现比例控制是最佳的。是的,然而,构建真正的发现保证程序具有挑战性,因为它将权力集中在用户根据他们的特定兴趣或专业知识选择的某些特征集上。我们提出了一个程序,允许用户以预定的功能集为目标电源,也就是说,\"焦点集。“尽管如此,该方法还允许推断事后选择的特征集,也就是说,\"非焦点集,\“为此,我们推导了一个由插值限制的真正的发现较低的置信度。我们的程序是由部分真实发现保证程序与Holm\的程序相结合而构建的,是封闭测试程序的保守捷径。仿真研究证实,对于焦点集,我们方法的统计能力相对较高,以非聚焦集的功率为代价,根据需要。此外,我们研究了具有特定结构的集合的功率属性,例如,树和有向无环图。我们还在可复制性分析的背景下将我们的方法与AdaFilter进行了比较。通过基因本体分析在基因表达数据中说明了我们方法的应用。
    Closed testing has recently been shown to be optimal for simultaneous true discovery proportion control. It is, however, challenging to construct true discovery guarantee procedures in such a way that it focuses power on some feature sets chosen by users based on their specific interest or expertise. We propose a procedure that allows users to target power on prespecified feature sets, that is, \"focus sets.\" Still, the method also allows inference for feature sets chosen post hoc, that is, \"nonfocus sets,\" for which we deduce a true discovery lower confidence bound by interpolation. Our procedure is built from partial true discovery guarantee procedures combined with Holm\'s procedure and is a conservative shortcut to the closed testing procedure. A simulation study confirms that the statistical power of our method is relatively high for focus sets, at the cost of power for nonfocus sets, as desired. In addition, we investigate its power property for sets with specific structures, for example, trees and directed acyclic graphs. We also compare our method with AdaFilter in the context of replicability analysis. The application of our method is illustrated with a gene ontology analysis in gene expression data.
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  • 文章类型: Journal Article
    在精准医学中,估计预期收益(EB)子集有很大的兴趣,即,基于基线特征的集合,预期受益于新的治疗的患者的子集。有许多统计方法来估计EB子集,其中大多数都会产生“点估计”,而没有解决不确定性的信心声明。EB子集的置信区间最近才被定义,它们的构建是方法论研究的新领域。本文提出了一种用于EB子集估计和置信区间构造的伪响应方法。与现有方法相比,伪反应方法使我们能够专注于对条件治疗效应函数进行建模(与给定治疗和基线协变量的条件均值结果相反),并且能够整合来自基线协变量的信息,这些信息不参与定义EB子集.仿真结果表明,合并此类协变量可以提高估计效率并减少EB子集的置信区间大小。该方法适用于比较两种治疗HIV感染的药物的随机临床试验。
    In precision medicine, there is much interest in estimating the expected-to-benefit (EB) subset, i.e. the subset of patients who are expected to benefit from a new treatment based on a collection of baseline characteristics. There are many statistical methods for estimating the EB subset, most of which produce a \'point estimate\' without a confidence statement to address uncertainty. Confidence intervals for the EB subset have been defined only recently, and their construction is a new area for methodological research. This article proposes a pseudo-response approach to EB subset estimation and confidence interval construction. Compared to existing methods, the pseudo-response approach allows us to focus on modelling a conditional treatment effect function (as opposed to the conditional mean outcome given treatment and baseline covariates) and is able to incorporate information from baseline covariates that are not involved in defining the EB subset. Simulation results show that incorporating such covariates can improve estimation efficiency and reduce the size of the confidence interval for the EB subset. The methodology is applied to a randomized clinical trial comparing two drugs for treating HIV infection.
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  • 文章类型: Journal Article
    大脑有效连接分析量化一个神经元或区域对另一个神经元或区域的直接影响,了解有效的连接模式如何受到受试者条件变化的影响具有极大的科学意义。向量自回归(VAR)是解决此类问题的有用工具。然而,当存在测量误差时,解决方案很少,当有多个主题时,当焦点是转移矩阵的推断时。在这篇文章中,研究了具有测量误差和多主体的高维VAR模型下的转移矩阵推断问题。我们提出了一个同时测试程序,具有三个关键组成部分:改进的期望最大化(EM)算法,基于给定协变量的滞后自协方差的偏差校正估计器的张量回归的检验统计量,和适当的阈值同时测试。我们为修改后的EM的估计量建立了统一的一致性,并表明后续测试实现了一致的错误发现控制,它的力量渐近地接近一个。我们通过模拟和任务诱发功能磁共振成像的大脑连通性研究证明了我们方法的有效性。
    Brain-effective connectivity analysis quantifies directed influence of one neural element or region over another, and it is of great scientific interest to understand how effective connectivity pattern is affected by variations of subject conditions. Vector autoregression (VAR) is a useful tool for this type of problems. However, there is a paucity of solutions when there is measurement error, when there are multiple subjects, and when the focus is the inference of the transition matrix. In this article, we study the problem of transition matrix inference under the high-dimensional VAR model with measurement error and multiple subjects. We propose a simultaneous testing procedure, with three key components: a modified expectation-maximization (EM) algorithm, a test statistic based on the tensor regression of a bias-corrected estimator of the lagged auto-covariance given the covariates, and a properly thresholded simultaneous test. We establish the uniform consistency for the estimators of our modified EM, and show that the subsequent test achieves both a consistent false discovery control, and its power approaches one asymptotically. We demonstrate the efficacy of our method through both simulations and a brain connectivity study of task-evoked functional magnetic resonance imaging.
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  • 文章类型: Journal Article
    越来越多的现代科学问题出现在基因组学等领域,神经生物学,和空间流行病学涉及对数千个相关特征的测量和分析,这些特征可能在任意强的水平上随机依赖。在这项工作中,我们考虑特征遵循多变量正态分布的情况。我们证明了依赖性表现为特征之间共享的随机变化,标准方法可能由于依赖性而产生高度不稳定的推断,即使在过程中完全参数化和利用依赖性。我们提出了一个“跨维度推理”框架,通过建模和删除特征之间共享的变化来缓解由于依赖而导致的问题,同时也适当地正则化跨特征的估计。我们演示了从感兴趣的科学应用得出的场景中同时进行点估计和多个假设检验的框架。
    A growing number of modern scientific problems in areas such as genomics, neurobiology, and spatial epidemiology involve the measurement and analysis of thousands of related features that may be stochastically dependent at arbitrarily strong levels. In this work, we consider the scenario where the features follow a multivariate Normal distribution. We demonstrate that dependence is manifested as random variation shared among features, and that standard methods may yield highly unstable inference due to dependence, even when the dependence is fully parameterized and utilized in the procedure. We propose a \"cross-dimensional inference\" framework that alleviates the problems due to dependence by modeling and removing the variation shared among features, while also properly regularizing estimation across features. We demonstrate the framework on both simultaneous point estimation and multiple hypothesis testing in scenarios derived from the scientific applications of interest.
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  • 文章类型: Journal Article
    生存时间是许多随机对照试验的主要终点,治疗效果通常在比例风险假设下通过风险比进行量化。意识到在许多情况下,这个假设是先验违反的,例如,由于药物作用的延迟发作。在这些情况下,对风险比估计的解释是模糊的,并且有必要对替代参数进行统计推断以量化治疗效果。我们考虑里程碑生存概率或分位数的差异或比率,限制平均生存时间的差异,和平均危险比值得关注。通常,需要报告一个以上的参数以评估可能的治疗益处,在验证性试验中,根据推理程序需要针对多重性进行调整。简单的Bonferroni调整可能过于保守,因为不同的感兴趣参数通常显示出相当大的相关性。因此,需要考虑相关性的同时推理程序。通过使用上述参数的计数过程表示,我们证明了它们的估计是渐近多变量正态的,并给出了它们的协方差矩阵的估计。我们根据参数提出了多个测试程序和同时的置信区间。此外,logrank测试可能包含在框架中。通过仿真研究了有限样本I型错误率和功率。用来自肿瘤学的实例说明所述方法。在R包nph中提供了软件实现。
    Survival time is the primary endpoint of many randomized controlled trials, and a treatment effect is typically quantified by the hazard ratio under the assumption of proportional hazards. Awareness is increasing that in many settings this assumption is a priori violated, for example, due to delayed onset of drug effect. In these cases, interpretation of the hazard ratio estimate is ambiguous and statistical inference for alternative parameters to quantify a treatment effect is warranted. We consider differences or ratios of milestone survival probabilities or quantiles, differences in restricted mean survival times, and an average hazard ratio to be of interest. Typically, more than one such parameter needs to be reported to assess possible treatment benefits, and in confirmatory trials, the according inferential procedures need to be adjusted for multiplicity. A simple Bonferroni adjustment may be too conservative because the different parameters of interest typically show considerable correlation. Hence simultaneous inference procedures that take into account the correlation are warranted. By using the counting process representation of the mentioned parameters, we show that their estimates are asymptotically multivariate normal and we provide an estimate for their covariance matrix. We propose according to the parametric multiple testing procedures and simultaneous confidence intervals. Also, the logrank test may be included in the framework. Finite sample type I error rate and power are studied by simulation. The methods are illustrated with an example from oncology. A software implementation is provided in the R package nph.
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  • 文章类型: Journal Article
    当存在多种类型的事件或研究受试者集群时,会出现多变量间隔删失数据。使得事件时间潜在地相关,并且当每个事件仅已知在特定时间间隔内发生时。我们通过边际比例风险模型制定了潜在时变协变量对多变量事件时间的影响,同时未指定相关事件时间的依赖结构。我们在所有事件时间都是独立的工作假设下构造了非参数伪似然,我们提供了一个简单而稳定的EM型算法。所得到的回归参数的非参数最大伪似然估计量显示为一致且渐近正态,具有极限协方差矩阵,该矩阵可以在相关事件时间的任意依赖结构下通过三明治估计器进行一致估计。我们通过广泛的模拟研究来评估所提出方法的性能,并将其应用于社区动脉粥样硬化风险研究的数据。
    Multivariate interval-censored data arise when there are multiple types of events or clusters of study subjects, such that the event times are potentially correlated and when each event is only known to occur over a particular time interval. We formulate the effects of potentially time-varying covariates on the multivariate event times through marginal proportional hazards models while leaving the dependence structures of the related event times unspecified. We construct the nonparametric pseudolikelihood under the working assumption that all event times are independent, and we provide a simple and stable EM-type algorithm. The resulting nonparametric maximum pseudolikelihood estimators for the regression parameters are shown to be consistent and asymptotically normal, with a limiting covariance matrix that can be consistently estimated by a sandwich estimator under arbitrary dependence structures for the related event times. We evaluate the performance of the proposed methods through extensive simulation studies and present an application to data from the Atherosclerosis Risk in Communities Study.
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  • 文章类型: Journal Article
    形态测量(即,形状和大小)皮质结构解剖结构的差异与神经发育和神经精神疾病有关。这种差异可以通过称为标记皮质距离图(LCDM)的强大工具进行量化和检测。LCDM方法为特定皮质结构(或组织)提供标记的灰质(GM)体素与GM/白质(WM)表面的距离。在这里,我们描述了一种使用LCDM距离分析特定组织中形态测量变异性的方法。为了提取LCDM距离提供的更多信息,我们执行LCDM距离的汇集和审查。特别是,我们在LCDM距离上采用了Brown-Forsythe(BF)方差齐性(HOV)检验。混合距离的HOV分析提供了由于所讨论的疾病引起的LCDM的形态测量变异性的总体分析。而审查距离的HOV分析表明这些差异的显著变化的位置(即,在距GM/WM表面的距离上,形态测量变异性开始显着)。我们还检查假设违规对LCDM距离的HOV分析的影响。特别是,我们证明了BFHOV检验对于假设违规是稳健的,例如对于合并和删失距离,残差与中位数的非正态性和样本内依赖性,并且对于在删失距离分析中发生的数据聚集是稳健的.我们建议将HOV分析作为分析分布/位置差异的补充工具。我们还将该方法应用于模拟的正常和指数数据集,并在满足更多基本假设时评估方法的性能。我们在一个真实的数据例子中说明了方法,即,腹侧内侧前额叶皮质(VMPFCs)中GM体素的LCDM距离,以观察抑郁症或抑郁症高风险对VMPFCs形态计量学的影响。此处使用的方法也适用于其他皮质结构的形态计量学分析。
    Morphometric (i.e., shape and size) differences in the anatomy of cortical structures are associated with neurodevelopmental and neuropsychiatric disorders. Such differences can be quantized and detected by a powerful tool called Labeled Cortical Distance Map (LCDM). The LCDM method provides distances of labeled gray matter (GM) voxels from the GM/white matter (WM) surface for specific cortical structures (or tissues). Here we describe a method to analyze morphometric variability in the particular tissue using LCDM distances. To extract more of the information provided by LCDM distances, we perform pooling and censoring of LCDM distances. In particular, we employ Brown-Forsythe (BF) test of homogeneity of variance (HOV) on the LCDM distances. HOV analysis of pooled distances provides an overall analysis of morphometric variability of the LCDMs due to the disease in question, while the HOV analysis of censored distances suggests the location(s) of significant variation in these differences (i.e., at which distance from the GM/WM surface the morphometric variability starts to be significant). We also check for the influence of assumption violations on the HOV analysis of LCDM distances. In particular, we demonstrate that BF HOV test is robust to assumption violations such as the non-normality and within sample dependence of the residuals from the median for pooled and censored distances and are robust to data aggregation which occurs in analysis of censored distances. We recommend HOV analysis as a complementary tool to the analysis of distribution/location differences. We also apply the methodology on simulated normal and exponential data sets and assess the performance of the methods when more of the underlying assumptions are satisfied. We illustrate the methodology on a real data example, namely, LCDM distances of GM voxels in ventral medial prefrontal cortices (VMPFCs) to see the effects of depression or being of high risk to depression on the morphometry of VMPFCs. The methodology used here is also valid for morphometric analysis of other cortical structures.
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  • 文章类型: Journal Article
    我们建议使用t过程的高斯运动学公式(tGKF)为任意维紧凑域上的功能参数构造同时置信带(SCB)。尽管tGKF依赖于高斯性,我们证明,即使观测值是非高斯过程,感兴趣参数的中心极限定理(CLT)也足以获得渐近精确的覆盖。作为概念证明,我们研究了功能信号加噪声模型,并得出了Lipshitz-Killing曲率估计器的CLT,tGKF中唯一的数据相关量。我们使用回归分析的尺度空间思想进一步讨论了具有加性观测噪声的离散采样的扩展。我们的理论工作伴随着一项模拟研究,比较了为人口均值构建SCB的不同方法。我们证明了tGKF优于最先进的方法,对小样本量具有精确的覆盖,并且只有Rademacher乘数-tbootstrap表现类似。另一个好处是,即使对于维度大于1的域,我们的SCB也可以快速计算。讨论了SCB在扩散张量成像(DTI)纤维(1D)和时空温度数据(2D)中的应用。
    We propose a construction of simultaneous confidence bands (SCBs) for functional parameters over arbitrary dimensional compact domains using the Gaussian Kinematic formula of t-processes (tGKF). Although the tGKF relies on Gaussianity, we show that a central limit theorem (CLT) for the parameter of interest is enough to obtain asymptotically precise covering even if the observations are non-Gaussian processes. As a proof of concept we study the functional signal-plus-noise model and derive a CLT for an estimator of the Lipshitz-Killing curvatures, the only data-dependent quantities in the tGKF. We further discuss extensions to discrete sampling with additive observation noise using scale space ideas from regression analysis. Our theoretical work is accompanied by a simulation study comparing different methods to construct SCBs for the population mean. We show that the tGKF outperforms state-of-the-art methods with precise covering for small sample sizes, and only a Rademacher multiplier-t bootstrap performs similarly well. A further benefit is that our SCBs are computational fast even for domains of dimension greater than one. Applications of SCBs to diffusion tensor imaging (DTI) fibers (1D) and spatio-temporal temperature data (2D) are discussed.
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  • 文章类型: Journal Article
    在过去的60年左右的时间里,关于多重比较和同时推断的许多研究都是为了比较几种人口手段。Spurrier似乎是第一个使用同时置信带研究几个简单线性回归线的多重比较的人。在本文中,我们扩展了Liu等人的工作。使用同步置信带对几个单变量线性回归模型进行有限比较,使用同步置信管对几个多变量线性回归模型进行有限比较。与当前的假设检验方法相比,我们展示了如何构建同步置信度管,以便为比较几个多元线性回归模型提供更多的信息推断。通过实例说明了这些方法。
    Much of the research on multiple comparison and simultaneous inference in the past 60 years or so has been for the comparisons of several population means. Spurrier seems to have been the first to investigate multiple comparisons of several simple linear regression lines using simultaneous confidence bands. In this paper, we extend the work of Liu et al. for finite comparisons of several univariate linear regression models using simultaneous confidence bands to finite comparisons of several multivariate linear regression models using simultaneous confidence tubes. We show how simultaneous confidence tubes can be constructed to allow more informative inferences for the comparison of several multivariate linear regression models than the current approach of hypotheses testing. The methods are illustrated with examples.
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  • 文章类型: Journal Article
    This paper studies simultaneous inference for factor loadings in the approximate factor model. We propose a test statistic based on the maximum discrepancy measure. Taking advantage of the fact that the test statistic can be approximated by the sum of the independent random variables, we develop a multiplier bootstrap procedure to calculate the critical value, and demonstrate the asymptotic size and power of the test. Finally, we apply our result to multiple testing problems by controlling the family-wise error rate (FWER). The conclusions are confirmed by simulations and real data analysis.
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