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众数位于边界时的贝叶斯因子近似AI 解读

Bayes factors, measuring the strength of evidence in favor of the null, are often used in the Bayesian approach to testing hypotheses. Laplace approximations to Bayes factors are convenient and quite accurate in many contexts. However, one usual assumption—the existence of an interior mode—does not always hold. The posterior mode can occur at the boundary of the parameter space. This article discusses the boundary mode Laplace's method for boundary modes, uses it to…

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神经传递分析中的层级混合模型AI 解读

Hierarchically structured mixture models are studied in the context of data analysis and inference on neural synaptic transmission characteristics in mammalian, and other, central nervous systems. Mixture structures arise due to uncertainties about the stochastic mechanisms governing the responses to electrochemical stimulation of individual neurotransmitter release sites at nerve junctions. Models attempt to capture such scientific features as the sensitivity of individual…

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适应非参数回归稀疏设计的插值方法：评论AI 解读

We suggest interpolation methods for overcoming the problem of sparse design in local linear smoothing. These methods are based on simple rules, determined by the kernel and bandwidth, for deciding when and where pseudo-design points should be added to augment the original design sequence. New ordinates for the added design points are computed by simple interpolation, then local linear smoothing is applied directly to the expanded dataset. The method is competitive with…

非参数回归中适应稀疏设计的插值方法AI 解读

We suggest interpolation methods for overcoming the problem of sparse design in local linear smoothing. These methods are based on simple rules, determined by the kernel and bandwidth, for deciding when and where pseudo-design points should be added to augment the original design sequence. New ordinates for the added design points are computed by simple interpolation, then local linear smoothing is applied directly to the expanded dataset. The method is competitive with…

相关潜在特质的高效矩阵抽样测评：美国全国教育进展评估实例AI 解读

We study the efficiency of administering different subsets of a large collection of items in a sample survey to different people to estimate the distribution of several correlated traits. The designs are motivated by examples from the National Assessment of Educational Progress, an ongoing survey of U.S. students in the fourth, eighth, and twelfth grades. In this survey the traits represent proficiency in different subjects. For example, the Mathematics assessment estimates…

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社会科学统计学AI 解读

Why learn statistics? describing data probability discrete random variables continuous random variables sampling distributions hypothesis testing and confidence intervals comparing two independent groups ANOVA - comparing two or more groups two-way designs comparing dependent groups multiple comparisons correlation and regression categorical data methods based on ranks.

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毒性严重程度数据中的无可观察不良效应水平AI 解读

Toxicity data are often categorized by severity of response and dose level with the assumption that there is a tolerated dose below which there is no toxicity. For data from a controlled experiment, the largest observed dose at or below the tolerated dose is called the no-observed-adverse-effect level (NOAEL). The problem of identifying the NOAEL can be viewed statistically as estimating the maximal observed dose for which there is no increased severity or frequency of toxic…

非线性混合效应模型中时变协变量测量误差的两步法：IGF-I 药代动力学应用AI 解读

The usual approach to the analysis of population pharmacokinetic studies is to represent the concentration-time data by a nonlinear mixed-effects model. Primary objectives are to characterize the pattern of drug disposition in the population and to identify individual-specific covariates associated with pharmacokinetic behavior. We consider data from a study of insulin-like growth factor I (IGF-I) administered by intravenous infusion to patients with severe head trauma.…

分组数据的稳健估计AI 解读

Here we investigate the robustness properties of the class of minimum power divergence estimators for grouped data. This class contains the classical maximum likelihood estimators for grouped data. We find that the bias of these estimators due to deviations from the assumed underlying model can be large. Therefore, we propose a more general class of estimators that allows us to construct robust procedures. By analogy with Hampel's theorem, we define optimal bounded influence…

区分优良与不良处理的最优划分程序AI 解读

This article considers partitioning a given set of competing treatments into two subsets with the purpose of separating good and bad treatments. (The qualities “good” and “bad” are defined in terms of the parameter vector of the underlying distribution family.) Regarding the probability of an incorrect partition, within the class of so-called natural procedures minimax solutions are derived under suitable distributional assumptions. These results extend previous…

基于数据深度与自助法的极限 P 值概念AI 解读

In this article we propose some new notions of limiting P values for hypothesis testing. The limiting P value (LP) here not only provides the usual attractive interpretation of a P value as the strength in support of the null hypothesis coming from the observed data, but also has several advantages. First, it allows us to resample directly from the empirical distribution (in the bootstrap implementations), rather than from the estimated population distribution satisfying the…

用于生存分析的随机网络模型AI 解读

We present methodology giving highly accurate approximations for Bayesian predictive densities and distribution functions of first passage times between states of a semi-Markov process with a finite number of states. When the states describe a degenerative disorder with an absorbing end state, such predictive distributions are the survival distributions of a patient. We illustrate these methods with a variety of examples, including data from the San Francisco AIDS study. We…

截断数据的半参数似然比推断AI 解读

In astronomic, demographic, epidemiologic, and other studies, the variable of interest, say the survival time, is often truncated by an associated variable. In many situations, the distribution of the truncation variable can be described by a parametric form. Unlike in the standard right-censorship model in which the censoring distribution is noninformative, knowledge of the truncation distribution can be used to improve estimation of the survival distribution. This article…

半参数变换模型下的生存概率预测AI 解读

Prediction of survival probabilities for future patients is one of the main goals of fitting survival data with regression models. In this article we consider a large class of semiparametric transformation models, which includes the well-known proportional hazards and proportional odds models, for the analysis of failure time data. Specifically, we propose pointwise and simultaneous confidence interval procedures for the survival probability of future patients with specific…

分类变量随机有序分布的贝叶斯分析AI 解读

This article considers a finite set of discrete distributions all having the same finite support. The problem of interest is to assess the strength of evidence produced by sampled data for a hypothesis of a specified stochastic ordering among the underlying distributions and to estimate these distributions subject to the ordering. We present a Bayesian approach that is an alternative to using the posterior probability of the hypothesis and the Bayes factor in favor of the…