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最小修复模型的次序统计性质、随机生成与拟合优度检验AI 解读

We present properties of statistics arising from the Block, Borges, and Savits age-dependent minimal repair model. These properties are analogous to the order statistic properties in homogeneous Poisson processes. These properties are exploited to obtain an algorithm for generating a realization from the minimal repair model, and for testing hypothesis concerning the initial distribution function or hazard function of the repair model.

条件对数线性结构的组合AI 解读

Graphical models offer simple and intuitive interpretations in terms of conditional independence relationships, and these are especially valuable when large numbers of variables are involved. In some settings, restrictions on experiments and other forms of data collection may result in our being able to estimate only parts of a large graphical model; for example, when the data in a large contingency table are extremely sparse. In other settings, we might use a model building…

一类局部与全局稳健的回归估计量AI 解读

We present a new class of regression estimates called generalized τ estimates. These estimates are defined by minimizing the τ scale of the weighted residuals, with weights that penalize high-leverage observations. Like the τ estimates, the generalized τ estimates utilize for their definition two loss functions, ρ1 and ρ2, which together with the weights can be chosen to achieve simultaneously high breakdown point, finite gross error sensitivity, and high efficiency. We…

预测与实现结果的比较：理论及收入变化应用AI 解读

Household surveys often elicit respondents' intentions or predictions of future outcomes. The survey questions may ask respondents to choose among a selection of (ordered) response categories. If panel data or repeated cross-sections are available, then predictions may be compared with realized outcomes. The categorical nature of the predictions data complicates this comparison, however. Generalizing previous findings on binary intentions data, we derive bounds on features…

来源国社会保障项目与不同类别美国移民AI 解读

This article uses a unique set of pooled cross-sectional and time series data to examine the annual rate of U.S. immigration during 1972–1991 from 60 source countries. One distinguishing feature of the article is that it breaks out and cross-classifies various classes of immigrants—numerically limited versus numerically exempt and new immigrant versus adjustment of status. A second distinguishing feature is that it utilizes a unique vector of variables relating to the…

利用最后一次迁移数据估计多状态转移风险率AI 解读

Following United Nations recommendations, many countries collect or publish internal migration data in last-move form, despite continuing uncertainty among researchers about how to estimate transition rates and probabilities from such information. “Last-move” data are a form of retrospective event history in which the only available information for each observational unit are the state at the time of a survey (ω), the last previous state (ψ), and the time at which the ψ → ω…

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偏头痛治疗的元分析：融合异质研究设计的信息AI 解读

Migraine headache is a common condition in the United States for which a wide range of drug and nondrug treatments are available. There is wide disagreement about which treatments are most effective; meta-analysis of existing clinical trials can help to bring existing evidence to bear on this question. Conducting a meta-analysis is a challenging statistical problem because of the absence of a uniform accepted definition of headache syndromes, the diversity of treatments, and…

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函数索引加权对数秩统计量的多用途检验AI 解读

Two-sample weighted log-rank statistics are used in the presence of right censoring to test whether failure times from two populations have different survival distributions. Kosorok has showed that large families of these statistics form stochastic processes indexed by weight functions, and that these function-indexed statistics can be used to construct versatile test procedures simultaneously sensitive to a wide array of both ordered hazards and stochastic ordering…

泊松过程同质性的调整得分检验AI 解读

Tests of homogeneity are being increasingly used for the analysis of event time data, but relatively little attention has been paid to their distributional properties in settings with small to moderate sample sizes. Here we consider tests of homogeneity for recurrent event data in which the null model is a Poisson process and the alternative is a mixed Poisson process. We examine score and adjusted score statistics in the context of parametric and semiparametric regression…

比较多个处理效应时结合单侧与双侧检验的优势AI 解读

We consider the one-way layout for comparing k treatment effects μ i , 1 ≤ i ≤ k. Hayter earlier proposed a one-sided studentized range test (OSRT) for testing the null hypothesis H μO: μ1 = μ2 = ··· = μ k against the simple ordered alternative HA : μ1 ≤ μ2 ≤ ··· ≤ μ k with at least one strict inequality. The OSRT gives a set of simultaneous confidence intervals for all ordered pairwise differences μ j - μ i , i < j. These intervals are one-sided and have infinite upper…

非参数回归问题中的改进估计量AI 解读

Linear estimators of multivariate means are considered. Generalizations of some well-known theorems about admissibility of linear estimators are given. The results then are applied to show that commonly used kernel-type estimators in nonparametric regression problems can be constructively improved in a simple way. An asymptotic result is described that gives a quantitative measure of the maximum improvement to be gained in certain situations. A theoretical bound shows that…

比例优势回归模型的半参数推断AI 解读

For fitting the proportional odds regression model with right-censored survival times, we introduce some weighted empirical odds functions. These functions are solutions of some self-consistency equations and have a nice martingale representation. From these functions, several classes of new regression estimators, such as the pseudo–maximum likelihood estimator, martingale residual-based estimators, and minimum distance estimators, are derived. These estimators have…

含随机效应与测量误差的重复事件半参数回归模型AI 解读

Statistical methodology is presented for the regression analysis of multiple events in the presence of random effects and measurement error. Omitted covariates are modeled as random effects. Our approach to parameter estimation and significance testing is to start with a naive model of semiparametric Poisson process regression, and then to adjust for random effects and any possible covariate measurement error. We illustrate the techniques with data from a randomized clinical…

非平稳时间序列的时变谱分析AI 解读

Modeling of nonstationary stochastic time series has found wide applications in speech processing, biomedical signal processing, seismology, and failure detection. Data from these fields have often been modeled as piecewise stationary processes with abrupt changes, and their time-varying spectral features have been studied with the help of spectrograms. A general class of piecewise locally stationary processes is introduced here that allows both abrupt and smooth changes in…

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聚类数据的扩展广义估计方程AI 解读

Typically, analysis of data consisting of multiple observations on a cluster is complicated by within-cluster correlation. Estimating equations for generalized linear modeling of clustered data have recently received much attention. This article proposes an extension to the generalized estimating equation method proposed by Liang and Zeger, which treats within-cluster correlations as nuisance parameters. Using ideas from extended quasi-likelihood, estimating equations for…

利用平滑 ROC 曲线概括和比较诊断系统AI 解读

Receiver operating characteristic (ROC) curves are used for summarizing the performance of imperfect diagnostic systems, especially in biomedical research. These curves are also appropriate for summarizing the performance of a discriminant analysis but are under-utilized by statisticians. This article is illustrates the use of these curves for comparing competing diagnostic systems, develops new estimation methods based on kernel density estimation, and studies the…

正电子发射断层成像及广义反卷积模型的变异性评估AI 解读

The problem of variance assessment for positron emission tomography (PET) image reconstructions is considered in the context of generalized deconvolution. A refinement of an approximate technique proposed by Carson and colleagues is examined. Computational implications of representing the reconstruction kernel in terms of a weighted sum of Gaussian densities are developed. Bias and variance characteristics of the resulting variance estimators are examined by numerical…

逮捕率的层级贝叶斯分析AI 解读

A Bayesian hierarchical model provides the basis for calibrating the crimes avoided by incarceration of individuals convicted of drug offenses compared to those convicted of nondrug offenses. Two methods for constructing reference priors for hierarchical models both lead to the same prior in the final model. We use Markov chain Monte Carlo methods to fit the model to data from a random sample of past arrest records of all felons convicted of drug trafficking, drug…

为估计共同成功概率而序贯选择两类实验AI 解读

To estimate a success probability p, two experiments are available: individual Bernoulli (p) trials or the product of τ individual Bernoulli (p) trials. This problem has its roots in reliability where either single components can be tested or a system of τ identical components can be tested. A total of N experiments can be performed, and the problem is to sequentially select some combination (allocation) of these two experiments, along with an estimator of p, to achieve low…

估计有限总体中的类别数量AI 解读

We use an extension of the generalized jackknife approach of Gray and Schucany to obtain new nonparametric estimators for the number of classes in a finite population of known size. We also show that generalized jackknife estimators are closely related to certain Horvitz–Thompson estimators, to an estimator of Shlosser, and to estimators based on sample coverage. In particular, the generalized jackknife approach leads to a modification of Shlosser's estimator that does not…