我们为上市度量标准提供了贝叶斯一致性的简单条件。该技术的关键是三角形不等式,使我们能够明确地使用弱收敛,这是预先进行的标准Kullback-Leibler支持条件的后果。另一个条件是确保密度的平滑版本不像原始密度那么远,从而处理可以太密切地跟踪数据的密度。纸质的一个关键结果是,与目前用于保护$ \ MathBB {L} _1 $一致性的人相比,我们使用较弱的条件展示了超级一致性。
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我们研究了非参数混合模型中的一致性以及回归的密切相关的混合物(也称为混合回归)模型,其中允许回归函数是非参数的,并且假定误差分布是高斯密度的卷积。我们在一般条件下构建统一的一致估计器,同时突出显示了将现有的点一致性结果扩展到均匀结果的几个疼痛点。最终的分析事实并非如此,并且在此过程中开发了几种新颖的技术工具。在混合回归的情况下,我们证明了回归函数的$ l^1 $收敛性,同时允许组件回归函数任意地相交,这带来了其他技术挑战。我们还考虑对一般(即非跨方向)非参数混合物的概括。
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Consider $n$ points independently sampled from a density $p$ of class $\mathcal{C}^2$ on a smooth compact $d$-dimensional sub-manifold $\mathcal{M}$ of $\mathbb{R}^m$, and consider the generator of a random walk visiting these points according to a transition kernel $K$. We study the almost sure uniform convergence of this operator to the diffusive Laplace-Beltrami operator when $n$ tends to infinity. This work extends known results of the past 15 years. In particular, our result does not require the kernel $K$ to be continuous, which covers the cases of walks exploring $k$NN-random and geometric graphs, and convergence rates are given. The distance between the random walk generator and the limiting operator is separated into several terms: a statistical term, related to the law of large numbers, is treated with concentration tools and an approximation term that we control with tools from differential geometry. The convergence of $k$NN Laplacians is detailed.
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Mixtures of regression are a powerful class of models for regression learning with respect to a highly uncertain and heterogeneous response variable of interest. In addition to being a rich predictive model for the response given some covariates, the parameters in this model class provide useful information about the heterogeneity in the data population, which is represented by the conditional distributions for the response given the covariates associated with a number of distinct but latent subpopulations. In this paper, we investigate conditions of strong identifiability, rates of convergence for conditional density and parameter estimation, and the Bayesian posterior contraction behavior arising in finite mixture of regression models, under exact-fitted and over-fitted settings and when the number of components is unknown. This theory is applicable to common choices of link functions and families of conditional distributions employed by practitioners. We provide simulation studies and data illustrations, which shed some light on the parameter learning behavior found in several popular regression mixture models reported in the literature.
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Neural networks (NN) play a central role in modern Artificial intelligence (AI) technology and has been successfully used in areas such as natural language processing and image recognition. While majority of NN applications focus on prediction and classification, there are increasing interests in studying statistical inference of neural networks. The study of NN statistical inference can enhance our understanding of NN statistical proprieties. Moreover, it can facilitate the NN-based hypothesis testing that can be applied to hypothesis-driven clinical and biomedical research. In this paper, we propose a sieve quasi-likelihood ratio test based on NN with one hidden layer for testing complex associations. The test statistic has asymptotic chi-squared distribution, and therefore it is computationally efficient and easy for implementation in real data analysis. The validity of the asymptotic distribution is investigated via simulations. Finally, we demonstrate the use of the proposed test by performing a genetic association analysis of the sequencing data from Alzheimer's Disease Neuroimaging Initiative (ADNI).
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Quantifying the deviation of a probability distribution is challenging when the target distribution is defined by a density with an intractable normalizing constant. The kernel Stein discrepancy (KSD) was proposed to address this problem and has been applied to various tasks including diagnosing approximate MCMC samplers and goodness-of-fit testing for unnormalized statistical models. This article investigates a convergence control property of the diffusion kernel Stein discrepancy (DKSD), an instance of the KSD proposed by Barp et al. (2019). We extend the result of Gorham and Mackey (2017), which showed that the KSD controls the bounded-Lipschitz metric, to functions of polynomial growth. Specifically, we prove that the DKSD controls the integral probability metric defined by a class of pseudo-Lipschitz functions, a polynomial generalization of Lipschitz functions. We also provide practical sufficient conditions on the reproducing kernel for the stated property to hold. In particular, we show that the DKSD detects non-convergence in moments with an appropriate kernel.
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我们为随机梯度Langevin动态(SGLD)建立了泛化误差界,在耗散度和平滑度的假设下,在采样/优化文献中得到了增加的环境。与非凸面设置中的SGLD的现有范围不同,由于样本大小的增加,我们的SGLD与SGL的界限不同,并且随着样本量的增加而衰减至零。利用均匀稳定性框架,我们通过利用Langevin扩散的Wasserstein收缩属性来建立无关的界限,这也允许我们规避需要使用LipsChitz的假设来绑定渐变的渐变。我们的分析还支持使用不同离散化方法的SGLD的变体,包括欧几里德投影,或使用非各向同性噪声。
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高斯平滑的最佳运输(GOT)框架,在Goldfeld等人开创。 (2020)并随后被一系列后续文件,在统计,机器学习,信息理论和相关领域的研究人员中迅速引起了注意。在其中做出的一个关键观察是,通过适应Get框架而不是其未平滑的对应物,可以提升用于使用经验测量来近似于近似真实数据生成分布的维度的诅咒。目前的论文表明,相关观察适用于离散指数家庭模型中非参数混合分布的估计,在Get成本下,非参数MLE的估计精度可以加速到多项式速率。这与基于无缝度量的经典子多项式速率鲜明对比,这不能从信息理论的角度来改进。我们分析中的一个关键步骤是建立高斯复杂的LipsChitz函数的新杰克逊型近似。这种洞察力弥补了分析非参数MLES和新的框架的现有技术。
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我们调查了一定类别的功能不等式,称为弱Poincar的不等式,以使Markov链的收敛性与均衡相结合。我们表明,这使得SubGoom测量收敛界的直接和透明的推导出用于独立的Metropolis - Hastings采样器和用于棘手似然性的伪边缘方法,后者在许多实际设置中是子表芯。这些结果依赖于马尔可夫链之间的新量化比较定理。相关证据比依赖于漂移/较小化条件的证据更简单,并且所开发的工具允许我们恢复并进一步延长特定情况的已知结果。我们能够为伪边缘算法的实际使用提供新的见解,分析平均近似贝叶斯计算(ABC)的效果以及独立平均值的产品,以及研究与之相关的逻辑重量的情况粒子边缘大都市 - 黑斯廷斯(PMMH)。
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我们在客观函数是多模态和/或具有鞍点的情况下,在某些情况下介​​绍了一个新的在线算法,以便在术语G-PFSO。支撑G-PFSO的关键元件是概率分布,该概率分布,其被示出为集中在目标参数值上,因为样品大小增加并且可以通过标准粒子滤波算法有效地估计(B)。该分布取决于学习速率,其中学习速率越快,它将更快地集中在搜索空间的所需元素上,但是G-PFSO的可能性不太可能从目标函数的局部最优值逃逸。为了实现具有慢的学习速率的快速收敛速度,G-PFSO利用平均的加速性,在随机梯度文献中众所周知。考虑到几个具有挑战性的估计问题,数值实验表明,具有高概率,G-PFSO成功地找到了目标函数的最高模式,并以最佳速率收敛到其全球最大化器。虽然这项工作的重点是预期的对数似然最大化,但所提出的方法及其理论更普遍适用于优化通过期望定义的函数。
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在本文中,我们研究了可分离的希尔伯特空间的回归问题,并涵盖了繁殖核希尔伯特空间的非参数回归。我们研究了一类光谱/正则化算法,包括脊回归,主成分回归和梯度方法。我们证明了最佳,高概率的收敛性在研究算法的规范变体方面,考虑到对假设空间的能力假设以及目标函数的一般源条件。因此,我们以最佳速率获得了几乎确定的收敛结果。我们的结果改善并推广了先前的结果,以填补了无法实现的情况的理论差距。
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广义贝叶斯推理使用损失函数而不是可能性的先前信仰更新,因此可以用于赋予鲁棒性,以防止可能的错误规范的可能性。在这里,我们认为广泛化的贝叶斯推论斯坦坦差异作为损失函数的损失,由应用程序的可能性含有难治性归一化常数。在这种情况下,斯坦因差异来避免归一化恒定的评估,并产生封闭形式或使用标准马尔可夫链蒙特卡罗的通用后出版物。在理论层面上,我们显示了一致性,渐近的正常性和偏见 - 稳健性,突出了这些物业如何受到斯坦因差异的选择。然后,我们提供关于一系列棘手分布的数值实验,包括基于内核的指数家庭模型和非高斯图形模型的应用。
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三角形流量,也称为kn \“{o}的Rosenblatt测量耦合,包括用于生成建模和密度估计的归一化流模型的重要构建块,包括诸如实值的非体积保存变换模型的流行自回归流模型(真实的NVP)。我们提出了三角形流量统计模型的统计保证和样本复杂性界限。特别是,我们建立了KN的统计一致性和kullback-leibler估算器的rospblatt的kullback-leibler估计的有限样本会聚率使用实证过程理论的工具测量耦合。我们的结果突出了三角形流动下播放功能类的各向异性几何形状,优化坐标排序,并导致雅各比比流动的统计保证。我们对合成数据进行数值实验,以说明我们理论发现的实际意义。
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We consider the problem of estimating the optimal transport map between a (fixed) source distribution $P$ and an unknown target distribution $Q$, based on samples from $Q$. The estimation of such optimal transport maps has become increasingly relevant in modern statistical applications, such as generative modeling. At present, estimation rates are only known in a few settings (e.g. when $P$ and $Q$ have densities bounded above and below and when the transport map lies in a H\"older class), which are often not reflected in practice. We present a unified methodology for obtaining rates of estimation of optimal transport maps in general function spaces. Our assumptions are significantly weaker than those appearing in the literature: we require only that the source measure $P$ satisfies a Poincar\'e inequality and that the optimal map be the gradient of a smooth convex function that lies in a space whose metric entropy can be controlled. As a special case, we recover known estimation rates for bounded densities and H\"older transport maps, but also obtain nearly sharp results in many settings not covered by prior work. For example, we provide the first statistical rates of estimation when $P$ is the normal distribution and the transport map is given by an infinite-width shallow neural network.
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量化概率分布之间的异化的统计分歧(SDS)是统计推理和机器学习的基本组成部分。用于估计这些分歧的现代方法依赖于通过神经网络(NN)进行参数化经验变化形式并优化参数空间。这种神经估算器在实践中大量使用,但相应的性能保证是部分的,并呼吁进一步探索。特别是,涉及的两个错误源之间存在基本的权衡:近似和经验估计。虽然前者需要NN课程富有富有表现力,但后者依赖于控制复杂性。我们通过非渐近误差界限基于浅NN的基于浅NN的估计的估算权,重点关注四个流行的$ \ mathsf {f} $ - 分离 - kullback-leibler,chi squared,squared hellinger,以及总变异。我们分析依赖于实证过程理论的非渐近功能近似定理和工具。界限揭示了NN尺寸和样品数量之间的张力,并使能够表征其缩放速率,以确保一致性。对于紧凑型支持的分布,我们进一步表明,上述上三次分歧的神经估算器以适当的NN生长速率接近Minimax率 - 最佳,实现了对数因子的参数速率。
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找到Reset中的参数的最佳配置是一个非凸显最小化问题,但一阶方法尽管如此,找到了过度分辨率制度的全局最优。通过将Reset的训练过程转化为梯度流部分微分方程(PDE)和检查该限制过程的收敛性能,我们研究了这种现象。假设激活函数为2美元 - 最佳或部分$ 1 $-homerence;正则Relu满足后一种条件。我们表明,如果Reset足够大,则深度和宽度根据代数上的准确性和置信水平,一阶优化方法可以找到适合培训数据的全局最小化器。
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离散状态空间代表了对统计推断的主要计算挑战,因为归一化常数的计算需要在大型或可能的无限集中进行求和,这可能是不切实际的。本文通过开发适合离散可怜的可能性的新型贝叶斯推理程序来解决这一计算挑战。受到连续数据的最新方法学进步的启发,主要思想是使用离散的Fisher Divergence更新有关模型参数的信念,以代替有问题的棘手的可能性。结果是可以使用标准计算工具(例如Markov Chain Monte Carlo)进行采样的广义后部,从而规避了棘手的归一化常数。分析了广义后验的统计特性,并具有足够的后验一致性和渐近正态性的条件。此外,提出了一种新颖的通用后代校准方法。应用程序在离散空间数据的晶格模型和计数数据的多元模型上介绍,在每种情况下,方法论都以低计算成本促进通用的贝叶斯推断。
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We develop and analyze M -estimation methods for divergence functionals and the likelihood ratios of two probability distributions. Our method is based on a non-asymptotic variational characterization of f -divergences, which allows the problem of estimating divergences to be tackled via convex empirical risk optimization. The resulting estimators are simple to implement, requiring only the solution of standard convex programs. We present an analysis of consistency and convergence for these estimators. Given conditions only on the ratios of densities, we show that our estimators can achieve optimal minimax rates for the likelihood ratio and the divergence functionals in certain regimes. We derive an efficient optimization algorithm for computing our estimates, and illustrate their convergence behavior and practical viability by simulations. 1
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Testing the significance of a variable or group of variables $X$ for predicting a response $Y$, given additional covariates $Z$, is a ubiquitous task in statistics. A simple but common approach is to specify a linear model, and then test whether the regression coefficient for $X$ is non-zero. However, when the model is misspecified, the test may have poor power, for example when $X$ is involved in complex interactions, or lead to many false rejections. In this work we study the problem of testing the model-free null of conditional mean independence, i.e. that the conditional mean of $Y$ given $X$ and $Z$ does not depend on $X$. We propose a simple and general framework that can leverage flexible nonparametric or machine learning methods, such as additive models or random forests, to yield both robust error control and high power. The procedure involves using these methods to perform regressions, first to estimate a form of projection of $Y$ on $X$ and $Z$ using one half of the data, and then to estimate the expected conditional covariance between this projection and $Y$ on the remaining half of the data. While the approach is general, we show that a version of our procedure using spline regression achieves what we show is the minimax optimal rate in this nonparametric testing problem. Numerical experiments demonstrate the effectiveness of our approach both in terms of maintaining Type I error control, and power, compared to several existing approaches.
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当回归函数属于标准的平滑类时,由衍生物的单变量函数组成,衍生物到达$(\ gamma + 1)$ th由Action Anclople或Ae界定的常见常数,众所周知,最小的收敛速率均值平均错误(MSE)是$ \左(\ FRAC {\ SIGMA ^ {2}} {n} \右)^ {\ frac {2 \ gamma + 2} {2 \ gamma + 3}} $ \伽玛$是有限的,样本尺寸$ n \ lightarrow \ idty $。从一个不可思议的观点来看,考虑有限$ N $,本文显示:对于旧的H \“较旧的和SoboLev类,最低限度最佳速率是$ \ frac {\ sigma ^ {2} \ left(\ gamma \ vee1 \右)$ \ frac {n} {\ sigma ^ {2}} \ precsim \ left(\ gamma \ vee1 \右)^ {2 \ gamma + 3} $和$ \ left(\ frac {\ sigma ^ {2}} {n} \右)^ {\ frac {2 \ gamma + 2} $ \ r \ frac {n} {\ sigma ^ {2}}} \ succsim \ left(\ gamma \ vee1 \右)^ {2 \ gamma + 3} $。为了建立这些结果,我们在覆盖和覆盖号码上获得上下界限,以获得$ k的广义H \“较旧的班级$ th($ k = 0,...,\ gamma $)衍生物由上面的参数$ r_ {k} $和$ \ gamma $ th衍生物是$ r _ {\ gamma + 1} - $ lipschitz (以及广义椭圆形的平滑功能)。我们的界限锐化了标准类的古典度量熵结果,并赋予$ \ gamma $和$ r_ {k} $的一般依赖。通过在$ r_ {k} = 1 $以下派生MIMIMAX最佳MSE率,$ r_ {k} \ LEQ \ left(k-1 \右)!$和$ r_ {k} = k!$(与后两个在我们的介绍中有动机的情况)在我们的新熵界的帮助下,我们展示了一些有趣的结果,无法在文献中的现有熵界显示。对于H \“较旧的$ D-$变化函数,我们的结果表明,归一渐近率$ \左(\ frac {\ sigma ^ {2}} {n}右)^ {\ frac {2 \ Gamma + 2} {2 \ Gamma + 2 + D}} $可能是有限样本中的MSE低估。
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