A flexible method is developed to construct a confidence interval for the frequency of a queried object in a very large data set, based on a much smaller sketch of the data. The approach requires no knowledge of the data distribution or of the details of the sketching algorithm; instead, it constructs provably valid frequentist confidence intervals for random queries using a conformal inference approach. After achieving marginal coverage for random queries under the assumption of data exchangeability, the proposed method is extended to provide stronger inferences accounting for possibly heterogeneous frequencies of different random queries, redundant queries, and distribution shifts. While the presented methods are broadly applicable, this paper focuses on use cases involving the count-min sketch algorithm and a non-linear variation thereof, to facilitate comparison to prior work. In particular, the developed methods are compared empirically to frequentist and Bayesian alternatives, through simulations and experiments with data sets of SARS-CoV-2 DNA sequences and classic English literature.
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A flexible conformal inference method is developed to construct confidence intervals for the frequencies of queried objects in very large data sets, based on a much smaller sketch of those data. The approach is data-adaptive and requires no knowledge of the data distribution or of the details of the sketching algorithm; instead, it constructs provably valid frequentist confidence intervals under the sole assumption of data exchangeability. Although our solution is broadly applicable, this paper focuses on applications involving the count-min sketch algorithm and a non-linear variation thereof. The performance is compared to that of frequentist and Bayesian alternatives through simulations and experiments with data sets of SARS-CoV-2 DNA sequences and classic English literature.
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本文开发了新型的保形方法,以测试是否从与参考集相同的分布中采样了新的观察结果。以创新的方式将感应性和偏置的共形推断融合,所描述的方法可以以原则性的方式基于已知的分布式数据的依赖侧信息重新权重标准p值,并且可以自动利用最强大的优势来自任何一级和二进制分类器的模型。该解决方案可以通过样品分裂或通过新颖的转置交叉验证+方案来实现,该方案与现有的交叉验证方法相比,由于更严格的保证,这也可能在共形推理的其他应用中有用。在研究错误的发现率控制和在具有几个可能的离群值的多个测试框架内的虚假发现率控制和功率之后,提出的解决方案被证明通过模拟以及用于图像识别和表格数据的应用超过了标准的共形P值。
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对未来观察的预测是一个重要且具有挑战性的问题。分别量化预测不确定性使用预测区域和预测分布的两种主流方法,后者认为更具信息性,因为它可以执行其他与预测相关的任务。有效性的标准概念(我们在这里称为1型有效性)着重于预测区域的覆盖范围,而与预测分布执行的其他与预测相关的任务相关的有效性概念则缺乏。在这里,我们提出了一个新概念,称为2型有效性,与这些其他预测任务有关。我们建立了2型有效性和相干性能之间的联系,并表明为实现它而需要不精确的概率考虑因素。我们继续表明,可以通过将共形预测输出作为辅音合理性度量的轮廓函数来实现两种类型的预测有效性。我们还基于新的非参数推论模型构建提供了保​​形预测的替代表征,其中辅音的出现是自然的,并证明了其有效性。
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现在通常用于高风险设置,如医疗诊断,如医疗诊断,那么需要不确定量化,以避免后续模型失败。无分发的不确定性量化(无分布UQ)是用户友好的范式,用于为这种预测创建统计上严格的置信区间/集合。批判性地,间隔/集合有效而不进行分布假设或模型假设,即使具有最多许多DataPoints也具有显式保证。此外,它们适应输入的难度;当输入示例很困难时,不确定性间隔/集很大,信号传达模型可能是错误的。在没有多大的工作和没有再培训的情况下,可以在任何潜在的算法(例如神经网络)上使用无分​​发方法,以产生置信度集,以便包含用户指定概率,例如90%。实际上,这些方法易于理解和一般,应用于计算机视觉,自然语言处理,深度加强学习等领域出现的许多现代预测问题。这种实践介绍是针对对无需统计学家的免费UQ的实际实施感兴趣的读者。我们通过实际的理论和无分发UQ的应用领导读者,从保形预测开始,并使无关的任何风险的分布控制,如虚假发现率,假阳性分布检测,等等。我们将包括Python中的许多解释性插图,示例和代码样本,具有Pytorch语法。目标是提供读者对无分配UQ的工作理解,使它们能够将置信间隔放在算法上,其中包含一个自包含的文档。
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覆盖率概率的估计,尤其是缺失的质量,是许多科学领域应用的经典统计问题。在本文中,我们研究了与随机数据压缩或素描有关的问题。这是一种新颖但实际上相关的观点,它是指必须根据真实数据的压缩和不完美的摘要或草图来估算覆盖范围的情况,因为完全数据或不同符号的经验频率都无法直接观察。我们的贡献是一种贝叶斯非参数方法,可从随机哈希概述的数据中估算覆盖概率,这也解决了恢复真实数据中不同计数和不同计数的挑战性问题,并具有特定的感兴趣的经验频率。拟议的贝叶斯估计量很容易适用于大规模分析,结合了事先进行的差异过程,尽管在更一般的Pitman-yor过程中涉及一些公开的计算挑战。通过数值实验和应用于Covid DNA序列,经典英语文献和IP地址的真实数据集的应用,我们的方法论的经验有效性得到了证明。
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We develop a general framework for distribution-free predictive inference in regression, using conformal inference. The proposed methodology allows for the construction of a prediction band for the response variable using any estimator of the regression function. The resulting prediction band preserves the consistency properties of the original estimator under standard assumptions, while guaranteeing finite-sample marginal coverage even when these assumptions do not hold. We analyze and compare, both empirically and theoretically, the two major variants of our conformal framework: full conformal inference and split conformal inference, along with a related jackknife method. These methods offer different tradeoffs between statistical accuracy (length of resulting prediction intervals) and computational efficiency. As extensions, we develop a method for constructing valid in-sample prediction intervals called rank-one-out conformal inference, which has essentially the same computational efficiency as split conformal inference. We also describe an extension of our procedures for producing prediction bands with locally varying length, in order to adapt to heteroskedascity in the data. Finally, we propose a model-free notion of variable importance, called leave-one-covariate-out or LOCO inference. Accompanying this paper is an R package conformalInference that implements all of the proposals we have introduced. In the spirit of reproducibility, all of our empirical results can also be easily (re)generated using this package.
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Deep neural networks are powerful tools to detect hidden patterns in data and leverage them to make predictions, but they are not designed to understand uncertainty and estimate reliable probabilities. In particular, they tend to be overconfident. We begin to address this problem in the context of multi-class classification by developing a novel training algorithm producing models with more dependable uncertainty estimates, without sacrificing predictive power. The idea is to mitigate overconfidence by minimizing a loss function, inspired by advances in conformal inference, that quantifies model uncertainty by carefully leveraging hold-out data. Experiments with synthetic and real data demonstrate this method can lead to smaller conformal prediction sets with higher conditional coverage, after exact calibration with hold-out data, compared to state-of-the-art alternatives.
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在这项工作中,我们对基本思想和新颖的发展进行了综述的综述,这是基于最小的假设的一种无创新的,无分配的,非参数预测的方法 - 能够以非常简单的方式预测集屈服在有限样本案例中,在统计意义上也有效。论文中提供的深入讨论涵盖了共形预测的理论基础,然后继续列出原始想法的更高级的发展和改编。
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本文衍生了置信区间(CI)和时间统一的置信序列(CS),用于从有限观测值中估算未知平均值的经典问题。我们提出了一种衍生浓度界限的一般方法,可以看作是著名的切尔诺夫方法的概括(和改进)。它的核心是基于推导一类新的复合非负胸腔,通过投注和混合方法与测试的连接很强。我们展示了如何将这些想法扩展到无需更换的情况下,这是另一个经过深入研究的问题。在所有情况下,我们的界限都适应未知的差异,并且基于Hoeffding或经验的Bernstein不平等及其最近的Supermartingale概括,经验上大大优于现有方法。简而言之,我们为四个基本问题建立了一个新的最先进的问题:在有或没有替换的情况下进行采样时,CS和CI进行有限的手段。
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在过去几十年中,已经提出了各种方法,用于估计回归设置中的预测间隔,包括贝叶斯方法,集合方法,直接间隔估计方法和保形预测方法。重要问题是这些方法的校准:生成的预测间隔应该具有预定义的覆盖水平,而不会过于保守。在这项工作中,我们从概念和实验的角度审查上述四类方法。结果来自各个域的基准数据集突出显示从一个数据集中的性能的大波动。这些观察可能归因于违反某些类别的某些方法所固有的某些假设。我们说明了如何将共形预测用作提供不具有校准步骤的方法的方法的一般校准程序。
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预测一组结果 - 而不是独特的结果 - 是统计学习中不确定性定量的有前途的解决方案。尽管有关于构建具有统计保证的预测集的丰富文献,但适应未知的协变量转变(实践中普遍存在的问题)还是一个严重的未解决的挑战。在本文中,我们表明具有有限样本覆盖范围保证的预测集是非信息性的,并提出了一种新型的无灵活分配方法PredSet-1Step,以有效地构建了在未知协方差转移下具有渐近覆盖范围保证的预测集。我们正式表明我们的方法是\ textIt {渐近上可能是近似正确},对大型样本的置信度有很好的覆盖误差。我们说明,在南非队列研究中,它在许多实验和有关HIV风险预测的数据集中实现了名义覆盖范围。我们的理论取决于基于一般渐近线性估计器的WALD置信区间覆盖范围的融合率的新结合。
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我们提出了置信度序列 - 置信区间序列,其均匀地随时间均匀 - 用于基于I.I.D的流的完整,完全有序集中的任何分布的量级。观察。我们提供用于跟踪固定定量的方法并同时跟踪所有定量。具体而言,我们提供具有小常数的明确表达式,其宽度以尽可能快的$ \ SQRT {t} \ log \ log t} $率,以及实证分布函数的非渐近浓度不等式以相同的速率均匀地持续持续。后者加强了Smirnov迭代对数的实证过程法,延长了DVORETZKY-KIEFER-WOLFOITZ不等式以均匀地保持一段时间。我们提供了一种新的算法和样本复杂性,用于在多武装强盗框架中选择具有大约最佳定量的臂。在仿真中,我们的方法需要比现有方法更少五到五十的样品。
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Classical asymptotic theory for statistical inference usually involves calibrating a statistic by fixing the dimension $d$ while letting the sample size $n$ increase to infinity. Recently, much effort has been dedicated towards understanding how these methods behave in high-dimensional settings, where $d$ and $n$ both increase to infinity together. This often leads to different inference procedures, depending on the assumptions about the dimensionality, leaving the practitioner in a bind: given a dataset with 100 samples in 20 dimensions, should they calibrate by assuming $n \gg d$, or $d/n \approx 0.2$? This paper considers the goal of dimension-agnostic inference; developing methods whose validity does not depend on any assumption on $d$ versus $n$. We introduce an approach that uses variational representations of existing test statistics along with sample splitting and self-normalization to produce a new test statistic with a Gaussian limiting distribution, regardless of how $d$ scales with $n$. The resulting statistic can be viewed as a careful modification of degenerate U-statistics, dropping diagonal blocks and retaining off-diagonal blocks. We exemplify our technique for some classical problems including one-sample mean and covariance testing, and show that our tests have minimax rate-optimal power against appropriate local alternatives. In most settings, our cross U-statistic matches the high-dimensional power of the corresponding (degenerate) U-statistic up to a $\sqrt{2}$ factor.
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算法稳定性是一种学习理论的概念,其表示对输入数据的改变的程度(例如,删除单个数据点)可能会影响回归算法的输出。了解算法的稳定性属性通常对许多下游应用程序有用 - 例如,已知稳定性导致所需的概括性属性和预测推理保证。然而,目前在实践中使用的许多现代算法太复杂,无法对其稳定性的理论分析,因此我们只能通过算法在各种数据集上的行为的实证探索来尝试建立这些属性。在这项工作中,我们为这种“黑匣子测试”奠定了一个正式的统计框架,而没有任何关于算法或数据分布的假设,并在任何黑匣子测试识别算法稳定性的能力方面建立基本界限。
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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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The notion of uncertainty is of major importance in machine learning and constitutes a key element of machine learning methodology. In line with the statistical tradition, uncertainty has long been perceived as almost synonymous with standard probability and probabilistic predictions. Yet, due to the steadily increasing relevance of machine learning for practical applications and related issues such as safety requirements, new problems and challenges have recently been identified by machine learning scholars, and these problems may call for new methodological developments. In particular, this includes the importance of distinguishing between (at least) two different types of uncertainty, often referred to as aleatoric and epistemic. In this paper, we provide an introduction to the topic of uncertainty in machine learning as well as an overview of attempts so far at handling uncertainty in general and formalizing this distinction in particular.
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在TAN(2006)边缘敏感模型下,在不观察到的混淆存在下构建平均处理效应的界限问题。结合涉及对冲倾向分数的现有表征具有对问题的新的分布稳健特征,我们提出了我们称之为“双重有效/双重尖锐”(DVD)估计的这些界限的新颖估算器。双重清晰度对应于DVD估计始终估计灵敏度模型所暗示的最有可能(即,夏普)的界限,即使当所有滋扰参数都适当一致时,即使在两个滋扰参数中的一个被击败并实现半污染参数之一。双倍有效性是部分识别的全新财产:DVD估计仍然提供有效,但即使在大多数滋扰参数都被遗漏时,仍然没有锐利。实际上,即使在DVDS点估计无法渐近正常的情况下,标准沃尔德置信区间也可能保持有效。在二进制结果的情况下,DVD估计是特别方便的并且在结果回归和倾向评分方面具有闭合形式的表达。我们展示了模拟研究中的DVD估计,以及对右心导管插入的案例研究。
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我们开发了一个框架,用于在线环境中使用有效的覆盖范围保证构建不确定性集,其中基础数据分布可以急剧(甚至对手)随着时间的推移而发生巨大变化。我们提出的技术非常灵活,因为它可以与任何在线学习算法集成,需要最低限度的实施工作和计算成本。我们方法比现有替代方案的关键优势(也基于共形推断)是我们不需要将数据分为培训和保持校准集。这使我们能够以完全在线的方式拟合预测模型,并利用最新的观察结果来构建校准的不确定性集。因此,与现有技术相反,(i)我们构建的集合可以迅速适应分布的新变化; (ii)我们的过程不需要在每个时间步骤进行改装。使用合成和现实世界的基准数据集,我们证明了理论的有效性以及提案对现有技术的提高绩效。为了证明所提出的方法的更大灵活性,我们展示了如何为多出输出回归问题构造有效的间隔,而以前的顺序校准方法由于不切实际的计算和内存需求而无法处理。
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套索是一种高维回归的方法,当时,当协变量$ p $的订单数量或大于观测值$ n $时,通常使用它。由于两个基本原因,经典的渐近态性理论不适用于该模型:$(1)$正规风险是非平滑的; $(2)$估算器$ \ wideHat {\ boldsymbol {\ theta}} $与true参数vector $ \ boldsymbol {\ theta}^*$无法忽略。结果,标准的扰动论点是渐近正态性的传统基础。另一方面,套索估计器可以精确地以$ n $和$ p $大,$ n/p $的订单为一。这种表征首先是在使用I.I.D的高斯设计的情况下获得的。协变量:在这里,我们将其推广到具有非偏差协方差结构的高斯相关设计。这是根据更简单的``固定设计''模型表示的。我们在两个模型中各种数量的分布之间的距离上建立了非反应界限,它们在合适的稀疏类别中均匀地固定在信号上$ \ boldsymbol {\ theta}^*$。作为应用程序,我们研究了借助拉索的分布,并表明需要校正程度对于计算有效的置信区间是必要的。
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