测量黑匣子预测算法中变量重要性的最流行方法是利用合成输入,这些输入结合了来自多个受试者的预测变量。这些输入可能是不可能的,身体上不可能的,甚至在逻辑上是不可能的。结果,对这种情况的预测可以基于数据,这与对黑匣子的训练非常不同。我们认为,当解释使用此类值时,用户不能相信预测算法的决定的解释。取而代之的是,我们主张一种称为同类沙普利的方法,该方法基于经济游戏理论,与大多数其他游戏理论方法不同,它仅使用实际观察到的数据来量化可变重要性。莎普利队的同伙通过缩小判断的主题的缩小,被认为与一个或多个功能上的目标主题相似。如果使用它来缩小队列对队列平均值有很大的不同,则功能很重要。我们在算法公平问题上进行了说明,其中必须将重要性归因于未经训练模型的保护变量。对于每个主题和每个预测变量,我们可以计算该预测因子对受试者的预测响应或对其实际响应的重要性。这些值可以汇总,例如在所有黑色受试者上,我们提出了一个贝叶斯引导程序来量化个人和骨料莎普利值的不确定性。
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可解释的AI(XAI)的基本任务是确定黑匣子功能$ f $做出的预测背后的最重要功能。 Petsiuk等人的插入和缺失测试。 (2018年)用于判断从最重要的对分类至最不重要的算法的质量。在回归问题的激励下,我们在曲线标准(AUC)标准下建立了一个公式,就$ f $的锚定分解中的某些主要效果和相互作用而言。我们找到了在输入到$ f $的随机排序下AUC的期望值的表达式,并提出了回归设置的直线上方的替代区域。我们使用此标准将集成梯度(IG)计算出的特征与内核Shap(KS)以及石灰,DeepLift,Vanilla梯度和输入$ \ times $ \ times $梯度方法进行比较。 KS在我们考虑的两个数据集中具有最好的总体性能,但是计算非常昂贵。我们发现IG几乎和KS一样好,同时更快。我们的比较问题包括一些对IG构成挑战的二进制输入,因为它必须使用可能的变量级别之间的值,因此我们考虑处理IG中二进制变量的方法。我们表明,通过其shapley值进行排序变量并不一定给出插入插入测试的最佳排序。但是,对于加性模型的单调函数(例如逻辑回归),它将做到这一点。
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基于Shapley值的功能归因在解释机器学习模型中很受欢迎。但是,从理论和计算的角度来看,它们的估计是复杂的。我们将这种复杂性分解为两个因素:(1)〜删除特征信息的方法,以及(2)〜可拖动估计策略。这两个因素提供了一种天然镜头,我们可以更好地理解和比较24种不同的算法。基于各种特征删除方法,我们描述了多种类型的Shapley值特征属性和计算每个类型的方法。然后,基于可进行的估计策略,我们表征了两个不同的方法家族:模型 - 不合时宜的和模型特定的近似值。对于模型 - 不合稳定的近似值,我们基准了广泛的估计方法,并将其与Shapley值的替代性但等效的特征联系起来。对于特定于模型的近似值,我们阐明了对每种方法的线性,树和深模型的障碍至关重要的假设。最后,我们确定了文献中的差距以及有希望的未来研究方向。
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We introduce the XPER (eXplainable PERformance) methodology to measure the specific contribution of the input features to the predictive or economic performance of a model. Our methodology offers several advantages. First, it is both model-agnostic and performance metric-agnostic. Second, XPER is theoretically founded as it is based on Shapley values. Third, the interpretation of the benchmark, which is inherent in any Shapley value decomposition, is meaningful in our context. Fourth, XPER is not plagued by model specification error, as it does not require re-estimating the model. Fifth, it can be implemented either at the model level or at the individual level. In an application based on auto loans, we find that performance can be explained by a surprisingly small number of features. XPER decompositions are rather stable across metrics, yet some feature contributions switch sign across metrics. Our analysis also shows that explaining model forecasts and model performance are two distinct tasks.
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即使有效,模型的使用也必须伴随着转换数据的各个级别的理解(上游和下游)。因此,需求增加以定义单个数据与算法可以根据其分析可以做出的选择(例如,一种产品或一种促销报价的建议,或代表风险的保险费率)。模型用户必须确保模型不会区分,并且也可以解释其结果。本文介绍了模型解释的重要性,并解决了模型透明度的概念。在保险环境中,它专门说明了如何使用某些工具来强制执行当今可以利用机器学习的精算模型的控制。在一个简单的汽车保险中损失频率估计的示例中,我们展示了一些解释性方法的兴趣,以适应目标受众的解释。
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Objectives: Discussions of fairness in criminal justice risk assessments typically lack conceptual precision. Rhetoric too often substitutes for careful analysis. In this paper, we seek to clarify the tradeoffs between different kinds of fairness and between fairness and accuracy.Methods: We draw on the existing literatures in criminology, computer science and statistics to provide an integrated examination of fairness and accuracy in criminal justice risk assessments. We also provide an empirical illustration using data from arraignments.Results: We show that there are at least six kinds of fairness, some of which are incompatible with one another and with accuracy.Conclusions: Except in trivial cases, it is impossible to maximize accuracy and fairness at the same time, and impossible simultaneously to satisfy all kinds of fairness. In practice, a major complication is different base rates across different legally protected groups. There is a need to consider challenging tradeoffs.
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公平性是确保机器学习(ML)预测系统不会歧视特定个人或整个子人群(尤其是少数族裔)的重要要求。鉴于观察公平概念的固有主观性,文献中已经引入了几种公平概念。本文是一项调查,说明了通过大量示例和场景之间的公平概念之间的微妙之处。此外,与文献中的其他调查不同,它解决了以下问题:哪种公平概念最适合给定的现实世界情景,为什么?我们试图回答这个问题的尝试包括(1)确定手头现实世界情景的一组与公平相关的特征,(2)分析每个公平概念的行为,然后(3)适合这两个元素以推荐每个特定设置中最合适的公平概念。结果总结在决策图中可以由从业者和政策制定者使用,以导航相对较大的ML目录。
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基于AI和机器学习的决策系统已在各种现实世界中都使用,包括医疗保健,执法,教育和金融。不再是牵强的,即设想一个未来,自治系统将推动整个业务决策,并且更广泛地支持大规模决策基础设施以解决社会最具挑战性的问题。当人类做出决定时,不公平和歧视的问题普遍存在,并且当使用几乎没有透明度,问责制和公平性的机器做出决定时(或可能会放大)。在本文中,我们介绍了\ textit {Causal公平分析}的框架,目的是填补此差距,即理解,建模,并可能解决决策设置中的公平性问题。我们方法的主要见解是将观察到数据中存在的差异的量化与基本且通常是未观察到的因果机制收集的因果机制的收集,这些机制首先会产生差异,挑战我们称之为因果公平的基本问题分析(FPCFA)。为了解决FPCFA,我们研究了分解差异和公平性的经验度量的问题,将这种变化归因于结构机制和人群的不同单位。我们的努力最终达到了公平地图,这是组织和解释文献中不同标准之间关系的首次系统尝试。最后,我们研究了进行因果公平分析并提出一本公平食谱的最低因果假设,该假设使数据科学家能够评估不同影响和不同治疗的存在。
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This paper proposes a novel approach to explain the predictions made by data-driven methods. Since such predictions rely heavily on the data used for training, explanations that convey information about how the training data affects the predictions are useful. The paper proposes a novel approach to quantify how different data-clusters of the training data affect a prediction. The quantification is based on Shapley values, a concept which originates from coalitional game theory, developed to fairly distribute the payout among a set of cooperating players. A player's Shapley value is a measure of that player's contribution. Shapley values are often used to quantify feature importance, ie. how features affect a prediction. This paper extends this to cluster importance, letting clusters of the training data act as players in a game where the predictions are the payouts. The novel methodology proposed in this paper lets us explore and investigate how different clusters of the training data affect the predictions made by any black-box model, allowing new aspects of the reasoning and inner workings of a prediction model to be conveyed to the users. The methodology is fundamentally different from existing explanation methods, providing insight which would not be available otherwise, and should complement existing explanation methods, including explanations based on feature importance.
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Machine learning can impact people with legal or ethical consequences when it is used to automate decisions in areas such as insurance, lending, hiring, and predictive policing. In many of these scenarios, previous decisions have been made that are unfairly biased against certain subpopulations, for example those of a particular race, gender, or sexual orientation. Since this past data may be biased, machine learning predictors must account for this to avoid perpetuating or creating discriminatory practices. In this paper, we develop a framework for modeling fairness using tools from causal inference. Our definition of counterfactual fairness captures the intuition that a decision is fair towards an individual if it is the same in (a) the actual world and (b) a counterfactual world where the individual belonged to a different demographic group. We demonstrate our framework on a real-world problem of fair prediction of success in law school. * Equal contribution. This work was done while JL was a Research Fellow at the Alan Turing Institute. 2 https://obamawhitehouse.archives.gov/blog/2016/05/04/big-risks-big-opportunities-intersection-big-dataand-civil-rights 31st Conference on Neural Information Processing Systems (NIPS 2017),
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在本文中,我们提出了一种新的可解释性形式主义,旨在阐明测试集的每个输入变量如何影响机器学习模型的预测。因此,我们根据训练有素的机器学习决策规则提出了一个群体的解释性形式,它们是根据其对输入变量分布的可变性的反应。为了强调每个输入变量的影响,这种形式主义使用信息理论框架,该框架量化了基于熵投影的所有输入输出观测值的影响。因此,这是第一个统一和模型不可知的形式主义,使数据科学家能够解释输入变量之间的依赖性,它们对预测错误的影响以及它们对输出预测的影响。在大型样本案例中提供了熵投影的收敛速率。最重要的是,我们证明,计算框架中的解释具有低算法的复杂性,使其可扩展到现实生活中的大数据集。我们通过解释通过在各种数据集上使用XGBoost,随机森林或深层神经网络分类器(例如成人收入,MNIST,CELEBA,波士顿住房,IRIS以及合成的)上使用的复杂决策规则来说明我们的策略。最终,我们明确了基于单个观察结果的解释性策略石灰和摇摆的差异。可以通过使用自由分布的Python工具箱https://gems-ai.aniti.fr/来复制结果。
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机器学习渗透到许多行业,这为公司带来了新的利益来源。然而,在人寿保险行业中,机器学习在实践中并未被广泛使用,因为在过去几年中,统计模型表明了它们的风险评估效率。因此,保险公司可能面临评估人工智能价值的困难。随着时间的流逝,专注于人寿保险行业的修改突出了将机器学习用于保险公司的利益以及通过释放数据价值带来的利益。本文回顾了传统的生存建模方法论,并通过机器学习技术扩展了它们。它指出了与常规机器学习模型的差异,并强调了特定实现在与机器学习模型家族中面对审查数据的重要性。在本文的补充中,已经开发了Python库。已经调整了不同的开源机器学习算法,以适应人寿保险数据的特殊性,即检查和截断。此类模型可以轻松地从该SCOR库中应用,以准确地模拟人寿保险风险。
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近年来,解决机器学习公平性(ML)和自动决策的问题引起了处理人工智能的科学社区的大量关注。已经提出了ML中的公平定义的一种不同的定义,认为不同概念是影响人口中个人的“公平决定”的不同概念。这些概念之间的精确差异,含义和“正交性”尚未在文献中完全分析。在这项工作中,我们试图在这个解释中汲取一些订单。
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Interpretability provides a means for humans to verify aspects of machine learning (ML) models and empower human+ML teaming in situations where the task cannot be fully automated. Different contexts require explanations with different properties. For example, the kind of explanation required to determine if an early cardiac arrest warning system is ready to be integrated into a care setting is very different from the type of explanation required for a loan applicant to help determine the actions they might need to take to make their application successful. Unfortunately, there is a lack of standardization when it comes to properties of explanations: different papers may use the same term to mean different quantities, and different terms to mean the same quantity. This lack of a standardized terminology and categorization of the properties of ML explanations prevents us from both rigorously comparing interpretable machine learning methods and identifying what properties are needed in what contexts. In this work, we survey properties defined in interpretable machine learning papers, synthesize them based on what they actually measure, and describe the trade-offs between different formulations of these properties. In doing so, we enable more informed selection of task-appropriate formulations of explanation properties as well as standardization for future work in interpretable machine learning.
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Shap是一种衡量机器学习模型中可变重要性的流行方法。在本文中,我们研究了用于估计外形评分的算法,并表明它是功能性方差分析分解的转换。我们使用此连接表明,在Shap近似中的挑战主要与选择功能分布的选择以及估计的$ 2^p $ ANOVA条款的数量有关。我们认为,在这种情况下,机器学习解释性和敏感性分析之间的联系是有照明的,但是直接的实际后果并不明显,因为这两个领域面临着不同的约束。机器学习的解释性问题模型可评估,但通常具有数百个(即使不是数千个)功能。敏感性分析通常处理物理或工程的模型,这些模型可能非常耗时,但在相对较小的输入空间上运行。
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We propose a criterion for discrimination against a specified sensitive attribute in supervised learning, where the goal is to predict some target based on available features. Assuming data about the predictor, target, and membership in the protected group are available, we show how to optimally adjust any learned predictor so as to remove discrimination according to our definition. Our framework also improves incentives by shifting the cost of poor classification from disadvantaged groups to the decision maker, who can respond by improving the classification accuracy.In line with other studies, our notion is oblivious: it depends only on the joint statistics of the predictor, the target and the protected attribute, but not on interpretation of individual features. We study the inherent limits of defining and identifying biases based on such oblivious measures, outlining what can and cannot be inferred from different oblivious tests.We illustrate our notion using a case study of FICO credit scores.
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在人类循环机器学习应用程序的背景下,如决策支持系统,可解释性方法应在不使用户等待的情况下提供可操作的见解。在本文中,我们提出了加速的模型 - 不可知论解释(ACME),一种可解释的方法,即在全球和本地层面迅速提供特征重要性分数。可以将acme应用于每个回归或分类模型的后验。 ACME计算功能排名不仅提供了一个什么,但它还提供了一个用于评估功能值的变化如何影响模型预测的原因 - 如果分析工具。我们评估了综合性和现实世界数据集的建议方法,同时也与福芙添加剂解释(Shap)相比,我们制作了灵感的方法,目前是最先进的模型无关的解释性方法。我们在生产解释的质量方面取得了可比的结果,同时急剧减少计算时间并为全局和局部解释提供一致的可视化。为了促进该领域的研究,为重复性,我们还提供了一种存储库,其中代码用于实验。
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目的:我们研究使用机器学习(ML)模型的可解释的累入预测,并在预测能力,稀疏性和公平性方面分析性能。与以前的作品不同,本研究列举了输出概率而不是二进制预测的可解释模型,并使用定量公平定义来评估模型。本研究还研究了模型是否可以横跨地理位置概括。方法:我们在佛罗里达州和肯塔基州的两个不同的刑事核查数据集上生成了黑盒和可解释的ML模型。我们将这些模型的预测性能和公平与目前用于司法系统中使用的两种方法进行了比较,以预测审前常规率:Arnold PSA和Compas。我们评估了所有模型的预测性能,可以在两次跨越两次预测六种不同类型犯罪的模型。结果:几种可解释的ML模型可以预测常规和黑盒ML模型,比Compas或Arnold PSA更准确。这些模型在实践中可能有用。类似于Arnold PSA,这些可解释模型中的一些可以作为一个简单的表格写入。其他可以使用一组可视化显示。我们的地理分析表明ML模型应分开培训,以便单独的位置并随时间更新。我们还为可​​解释模型提供了公平分析。结论:可解释的机器学习模型可以在预测准确性和公平性方面表现,也可以表现,也可以表现,也可以执行不可解释的方法和目前使用的风险评估尺度。机器学习模型对于单独培训,可以更准确地进行不同的位置,并保持最新。
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Artificial intelligence(AI) systems based on deep neural networks (DNNs) and machine learning (ML) algorithms are increasingly used to solve critical problems in bioinformatics, biomedical informatics, and precision medicine. However, complex DNN or ML models that are unavoidably opaque and perceived as black-box methods, may not be able to explain why and how they make certain decisions. Such black-box models are difficult to comprehend not only for targeted users and decision-makers but also for AI developers. Besides, in sensitive areas like healthcare, explainability and accountability are not only desirable properties of AI but also legal requirements -- especially when AI may have significant impacts on human lives. Explainable artificial intelligence (XAI) is an emerging field that aims to mitigate the opaqueness of black-box models and make it possible to interpret how AI systems make their decisions with transparency. An interpretable ML model can explain how it makes predictions and which factors affect the model's outcomes. The majority of state-of-the-art interpretable ML methods have been developed in a domain-agnostic way and originate from computer vision, automated reasoning, or even statistics. Many of these methods cannot be directly applied to bioinformatics problems, without prior customization, extension, and domain adoption. In this paper, we discuss the importance of explainability with a focus on bioinformatics. We analyse and comprehensively overview of model-specific and model-agnostic interpretable ML methods and tools. Via several case studies covering bioimaging, cancer genomics, and biomedical text mining, we show how bioinformatics research could benefit from XAI methods and how they could help improve decision fairness.
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The widely used 'Counterfactual' definition of Causal Effects was derived for unbiasedness and accuracy - and not generalizability. We propose a simple definition for the External Validity (EV) of Interventions and Counterfactuals. The definition leads to EV statistics for individual counterfactuals, and to non-parametric effect estimators for sets of counterfactuals (i.e., for samples). We use this new definition to discuss several issues that have baffled the original counterfactual formulation: out-of-sample validity, reliance on independence assumptions or estimation, concurrent estimation of multiple effects and full-models, bias-variance tradeoffs, statistical power, omitted variables, and connections to current predictive and explaining techniques. Methodologically, the definition also allows us to replace the parametric, and generally ill-posed, estimation problems that followed the counterfactual definition by combinatorial enumeration problems in non-experimental samples. We use this framework to generalize popular supervised, explaining, and causal-effect estimators, improving their performance across three dimensions (External Validity, Unconfoundness and Accuracy) and enabling their use in non-i.i.d. samples. We demonstrate gains over the state-of-the-art in out-of-sample prediction, intervention effect prediction and causal effect estimation tasks. The COVID19 pandemic highlighted the need for learning solutions to provide general predictions in small samples - many times with missing variables. We also demonstrate applications in this pressing problem.
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