论文检索

预测、估计与归因AI 解读

The scientific needs and computational limitations of the twentieth century fashioned classical statistical methodology. Both the needs and limitations have changed in the twenty-first, and so has the methodology. Large-scale prediction algorithms—neural nets, deep learning, boosting, support vector machines, random forests—have achieved star status in the popular press. They are recognizable as heirs to the regression tradition, but ones carried out at enormous scale and on…

最大似然估计的曲率与推断AI 解读

Maximum likelihood estimates are sufficient statistics in exponential families, but not in general. The theory of statistical curvature was introduced to measure the effects of MLE insufficiency in one-parameter families. Here, we analyze curvature in the more realistic venue of multiparameter families—more exactly, curved exponential families, a broad class of smoothly defined nonexponential family models. We show that within the set of observations giving the same value…

经验贝叶斯反卷积估计AI 解读

An unknown prior density $g(\\theta )$ has yielded realizations $\\Theta _1,\\ldots ,\\Theta _N$ . They are unobservable, but each $\\Theta _i$ produces an observable value $X_i$ according to a known probability mechanism, such as $X_i\\sim {\\rm Po}(\\Theta _i)$ . We wish to estimate $g(\\theta )$ from the observed sample $X_1,\\ldots ,X_N$ . Traditional asymptotic calculations are discouraging, indicating very slow nonparametric rates of convergence. In this article we…

模型选择后的估计与精度评估AI 解读

Classical statistical theory ignores model selection in assessing estimation accuracy. Here we consider bootstrap methods for computing standard errors and confidence intervals that take model selection into account. The methodology involves bagging, also known as bootstrap smoothing, to tame the erratic discontinuities of selection-based estimators. A useful new formula for the accuracy of bagging then provides standard errors for the smoothed estimators. Two examples,…

Tweedie 公式与选择偏差AI 解读

We suppose that the statistician observes some large number of estimates z(i), each with its own unobserved expectation parameter μ(i). The largest few of the z(i)'s are likely to substantially overestimate their corresponding μ(i)'s, this being an example of selection bias, or regression to the mean. Tweedie's formula, first reported by Robbins in 1956, offers a simple empirical Bayes approach for correcting selection bias. This paper investigates its merits and…

大规模预测问题的经验贝叶斯估计AI 解读

Classical prediction methods such as Fisher's linear discriminant function were designed for small-scale problems, where the number of predictors N is much smaller than the number of observations n. Modern scientific devices often reverse this situation. A microarray analysis, for example, might include n = 100 subjects measured on N = 10,000 genes, each of which is a potential predictor. This paper proposes an empirical Bayes approach to large-scale prediction, where the…

检验大小、功效与错误发现率AI 解读

Modern scientific technology has provided a new class of large-scale simultaneous inference problems, with thousands of hypothesis tests to consider at the same time. Microarrays epitomize this type of technology, but similar situations arise in proteomics, spectroscopy, imaging, and social science surveys. This paper uses false discovery rate methods to carry out both size and power calculations on large-scale problems. A simple empirical Bayes approach allows the false…

相关性与大规模同时显著性检验AI 解读

Large-scale hypothesis testing problems, with hundreds or thousands of test statistics zi to consider at once, have become familiar in current practice. Applications of popular analysis methods, such as false discovery rate techniques, do not require independence of the zi's, but their accuracy can be compromised in high-correlation situations. This article presents computational and theoretical methods for assessing the size and effect of correlation in large-scale testing.…

多元正态均值向量的最小体积置信域AI 解读

Summary Since Stein's original proposal in 1962, a series of papers have constructed confidence regions of smaller volume than the standard spheres for the mean vector of a multivariate normal distribution. A general approach to this problem is developed here and used to calculate a lower bound on the attainable volume. Bayes and fiducial methods are involved in the calculation. Scheffé-type problems are used to show that low volume by itself does not guarantee favourable…

预测误差的估计AI 解读

Having constructed a data-based estimation rule, perhaps a logistic regression or a classification tree, the statistician would like to know its performance as a predictor of future cases. There are two main theories concerning prediction error: (1) penalty methods such as Cp, Akaike's information criterion, and Stein's unbiased risk estimate that depend on the covariance between data points and their corresponding predictions; and (2) cross-validation and related…

最小角回归AI 解读

The purpose of model selection algorithms such as All Subsets, Forward Selection and Backward Elimination is to choose a linear model on the basis of the same set of data to which the model will be applied. Typically we have available a large collection of possible covariates from which we hope to select a parsimonious set for the efficient prediction of a response variable. Least Angle Regression (LARS), a new model selection algorithm, is a useful and less greedy version…

大规模同时假设检验AI 解读

Current scientific techniques in genomics and image processing routinely produce hypothesis testing problems with hundreds or thousands of cases to consider simultaneously. This poses new difficulties for the statistician, but also opens new opportunities. In particular, it allows empirical estimation of an appropriate null hypothesis. The empirical null may be considerably more dispersed than the usual theoretical null distribution that would be used for any one case…

Robbins、经验贝叶斯与微阵列AI 解读

Empirical Bayes was Herbert Robbins' most influential contribution to statistical theory. It is also an idea of great practical potential. That potential is realized in the analysis of microarrays, a new biogenetic technology for the simultaneous measurement of thousands of gene expression levels.

平滑器与 Cp、广义最大似然及扩展指数准则AI 解读

Nonparametric regression, often called smoothing, is a widely used data analysis method. The use of a smoother requires the choice of a smoothing parameter that by balancing fidelity and roughness controls how much smoothing is done. Two popular selection criteria for choosing the smoothing parameter are Cp and generalized maximum likelihood (GML). Each of these has its own problems. ForCp, the problem is its high variability, whereas for GML, the problem is its potentially…

微阵列实验的经验贝叶斯分析AI 解读

Microarrays are a novel technology that facilitates the simultaneous measurement of thousands of gene expression levels. A typical microarray experiment can produce millions of data points, raising serious problems of data reduction, and simultaneous inference. We consider one such experiment in which oligonucleotide arrays were employed to assess the genetic effects of ionizing radiation on seven thousand human genes. A simple nonparametric empirical Bayes model is…

散点图平滑器的选择准则AI 解读

Scatterplot smoothers estimate a regression function y = f(x) by local averaging of the observed data points (xi, yi). In using a smoother, the statistician must choose a “window width,” a crucial smoothing parameter that says just how locally the averaging is done. This paper concerns the data­based choice of a smoothing parameter for splinelike smoothers, focusing on the comparison of two popular methods, Cp and generalized maximum likelihood. The latter is the MLE within…

摘要暂缺

双重截断数据的非参数方法AI 解读

Truncated data play an important role in the statistical analysis of astronomical observations as well as in survival analysis. The motivating example for this article concerns a set of measurements on quasars in which there is double truncation. That is, the quasars are observed only if their luminosity occurs within a certain finite interval, bounded at both ends, with the interval varying for different observations. Nonparametric methods for the testing and estimation of…

区域判定问题AI 解读

In the problem of regions, we wish to know which one of a discrete set of possibilities applies to a continuous parameter vector. This problem arises in the following way: we compute a descriptive statistic from a set of data, notice an interesting feature and wish to assign a confidence level to that feature. For example, we compute a density estimate and notice that the estimate is bimodal. What confidence can we assign to bimodality? A natural way to measure confidence is…

改进交叉验证：.632+ 自助法AI 解读

A training set of data has been used to construct a rule for predicting future responses. What is the error rate of this rule? This is an important question both for comparing models and for assessing a final selected model. The traditional answer to this question is given by cross-validation. The cross-validation estimate of prediction error is nearly unbiased but can be highly variable. Here we discuss bootstrap estimates of prediction error, which can be thought of as…

摘要暂缺

利用专门构造的指数族进行密度估计AI 解读

We wish to estimate the probability density $g(y)$ that produced an observed random sample of vectors $y_1, y_2, \dots, y_n$. Estimates of $g(y)$ are traditionally constructed in two quite different ways: by maximum likelihood fitting within some parametric family such as the normal or by nonparametric methods such as kernel density estimation. These two methods can be combined by putting an exponential family "through" a kernel estimator. These are the specially designed…

合并似然的经验贝叶斯方法AI 解读

Suppose that several independent experiments are observed, each one yielding a likelihood L k (θ k ) for a real-valued parameter of interest θ k . For example, θ k might be the log-odds ratio for a 2 × 2 table relating to the kth population in a series of medical experiments. This article concerns the following empirical Bayes question: How can we combine all of the likelihoods L k to get an interval estimate for any one of the θ k 's, say θ1? The results are presented in…

合并似然的经验贝叶斯方法AI 解读

Suppose that several independent experiments are observed, each one yielding a likelihood L k (θ k ) for a real-valued parameter of interest θ k . For example, θ k might be the log-odds ratio for a 2 × 2 table relating to the kth population in a series of medical experiments. This article concerns the following empirical Bayes question: How can we combine all of the likelihoods L k to get an interval estimate for any one of the θ k 's, say θ1? The results are presented in…