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临床试验中的药物安全性评估AI 解读

Details the methods pharmaceutical companies employ to determine the safety profile of their drugs. Statistical procedures currently used or developed to analyze, display and compare the massive amounts of laboratory data collected from controlled clinical trials are surveyed.

概率论极限定理：独立随机变量序列AI 解读

Notations and abbreviations 1. Some basic concepts and theorems of probability theory 2. Probability inequalities for sums of independent random variables 3. Weak limit-theorems: convergence to infinitely divisible distributions 4. Weak limit-theorems: the central limit theorem and the weak law of large numbers 5. Rates of convergence in the central limit theorem 6. Strong limit theorems: the strong law of large numbers 7. Strong limit theorems: the law of the iterated…

利用有偏样本估计迟发疾病的发病率AI 解读

Consistent estimators are derived for the age-specific and lifetime incidence rates of late-onset diseases from censored, biased samples, using a discrete time model and a traditional assumption for size-biased sampling. The estimators are alternatives to the so-called index case estimators often used by epidemiologists under similar circumstances. The asymptotic normality of the proposed estimators is established and an adaptation of Greenwood's formula is given for…

泊松分布与二项分布的似然比检验AI 解读

The estimation of N in the binomial B(N, p) distribution is a considerably harder problem than the estimation of p. We approach it as a “boundary value” estimation and testing problem, where the boundary N = ∞ corresponds to a Poisson distribution for the data, whereas N < ∞ corresponds to a binomial distribution. The asymptotic distribution of the deviance statistic for testing the hypothesis that the true value of N is infinite is shown to be a 50–50 mixture between a…

连续时间纵向有序响应数据分析AI 解读

A simple Markov model is developed for assessing the predictive effect of time-dependent covariates on an intermittently observed ordinal response in continuous time. This is accomplished by reparameterizing an ergodic intensity matrix in terms of its equilibrium distribution and a parametrically independent component that assesses the rate of movement between ordinal categories. The effect of covariates on the equilibrium distribution can then be modeled using any link…

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贝叶斯序贯两阶段抽样AI 解读

We propose a sequential two-phase sample design to accommodate applications where conventional two-phase sampling cannot be used. First, we derive the optimal, the optimal myopic, and several approximate optimal myopic sequential decision procedures for subsampling a first-phase sample. Then we compare our procedure to that of the optimal (nonsequential) conventional two-phase sample design. In our application, the objective is inference about the age distribution of a…

方差分量模型的贝叶斯方法AI 解读

An exact Bayesian analysis can be performed for normal theory variance components models, using importance sampling. But remarkably accurate approximations are available using the Laplacian T-approximation introduced by Leonard, Hsu, and Ritter. Instead of maximizing the joint posterior density, conditional upon the parameter of interest, a device described by O'Hagan is used first. The Bayesian estimators are compared to the Lindley—Stein shrinkage estimators and the…

两样本问题中的分位数比较函数及诊断标志物比较应用AI 解读

In this article a control percentile test, a chi-squared test, and a Kolmogorov-type test are proposed for comparing two distributions from incomplete survival data. These tests are obtained by examining a vertical shift comparison function at a single point, a finite number of points, and an entire set of points on an interval. The proposed methods also have applications in receiver operating characteristic (ROC) analysis, which has been widely used in such diverse fields…

一般线性模型中响应变量的测量误差AI 解读

Problems where there is measurement error in the response variable in a general linear model are considered. With Y denoting the true value and U the observed/surrogate value, a rich class of measurement error models is considered in which (a) the mean of U given Y = y can be either linear or nonlinear in y, (b) the variance of U given Y = y can depend on y, and (c) the parameters in the model for U given Y can change across observations in the study. This could occur, for…

基于受扰直方图数据的间接密度估计带宽选择AI 解读

Motivated by a number of practical applications, we consider a class of indirect nonparametric density estimation problems in which the observed data consist of a histogram of binned empirically corrected counts. Due to variability in the process of correction, the histogram cannot be modeled in terms of simple scaled Poisson statistics. This departure necessitates the development of a new methodology for bandwidth selection. A variant of the method of unbiased risk…

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…

插补调查数据的方差估计：评论AI 解读

Unit nonresponse and item nonresponse both occur frequently in surveys. Unit nonresponse is customarily handled by weighting adjustment, whereas item nonresponse is usually treated by some form of imputation. In particular, deterministic or stochastic imputation is often used to assign values for missing item responses. We provide an account of some recent work on jackknife variance estimation based on adjusted imputed values, using only a single imputation and hence a…

利用工具变量识别因果效应：评论AI 解读

We outline a framework for causal inference in settings where assignment to a binary treatment is ignorable, but compliance with the assignment is not perfect so that the receipt of treatment is nonignorable. To address the problems associated with comparing subjects by the ignorable assignment-an intention-to-treat analysis-we make use of instrumental variables, which have long been used by economists in the context of regression models with constant treatment effects. We…

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概率、随机过程与排队论：计算机性能建模的数学AI 解读

There are three types: E -an exercise that requires only algebraic manipulation M -a mathematical derivation is required to do the problem Rthe problem is a research problem.An exercise is distinguished from a derivation in that the answer proceeds directly from material in the text and does not require additional analysis.Research problems differ from derivations in that they require more independent work by the student and may require outside reading.For each type of…

医学研究的统计方法AI 解读

Statistics in medicine the design of medical investigations - clinical trials and other methods measurement in medicine statistical inference regression analysis repeated measures analysis of variance and the analysis of covariance crossover designs the analysis of survival data multivariate data and principal components analysis statistical methods for classification - cluster analysis and assignment techniques time series analysis the analysis of observational techniques.…

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异方差线性模型的秩方法分析AI 解读

Heteroscedasticity often causes problems in the analysis of linear models. Frequently for such cases, scale is a function of the response. Here, for such models, a methodology is presented based on well-known rank-based procedures. The procedure is iterative. Using the residuals from an initial R estimate of the regression coefficients, scale is estimated by inverting a linear rank test for scale. This in turn leads to a weighted R estimate of the regression coefficients and…

基于平滑因子的偏最小二乘回归AI 解读

In this article we present a modification of partial least squares regression to account for inherent nonexchangeabilities of the columns of the design matrix. In chemometrics applications it is common to write the matrix as a bilinear form of latent variables and loadings. These loadings are often interpreted as sampled values of functions; hence they should exhibit a degree of smoothness. Our method forces the partial least squares factors to be smooth, by using a…

次序统计量中的 Fisher 信息AI 解读

When we have n independently and identically distributed observations, it is an interesting question how the Fisher information is distributed among order statistics. The recipe for the Fisher information in order statistics is easy, but the detailed calculation has been known to be complicated. An indirect approach, using a decomposition of the Fisher information in order statistics, simplifies the calculation. Some recurrence relations for the Fisher information in order…