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随机有序生存函数的逐点非参数极大似然估计AI 解读

In this paper, we consider estimation of survivor functions from groups of observations with right-censored data when the groups are subject to a stochastic ordering constraint. Many methods and algorithms have been proposed to estimate distribution functions under such restrictions, but none have completely satisfactory properties when the observations are censored. We propose a pointwise constrained nonparametric maximum likelihood estimator, which is defined at each time…

回归中响应选择与缺失数据问题的半参数方法AI 解读

Summary Suppose that data are generated according to the model f(y|x; θ) g(x), where y is a response and x are covariates. We derive and compare semiparametric likelihood and pseudolikelihood methods for estimating θ for situations in which units generated are not fully observed and in which it is impossible or undesirable to model the covariate distribution. The probability that a unit is fully observed may depend on y, and there may be a subset of covariates which is…

混合分布误设对混合效应 Logistic 模型拟合的影响AI 解读

Mixed-effects logistic models are often used to analyze binary response data which have been gathered in clusters, or groups. Responses are assumed to follow a logistic model with in clusters, with an intercept which varies across clusters according to a specified probability distribution G. In this paper we examine the performance of mixed-effects logistic regression analysis when a main component of the model, the mixture distribution, is misspecified. We show that, when…

拟合混合效应Logistic模型时混合分布误设的影响AI 解读

Mixed-effects logistic models are often used to analyze binary response data which have been gathered in clusters, or groups. Responses are assumed to follow a logistic model with in clusters, with an intercept which varies across clusters according to a specified probability distribution G. In this paper we examine the performance of mixed-effects logistic regression analysis when a main component of the model, the mixture distribution, is misspecified. We show that, when…

基于回顾性发现机制的推断：输血相关艾滋病数据分析AI 解读

In some epidemiologic studies, identification of individuals for study is dependent on the occurrence of some event. Once an individual is identified, the time of a previous event, termed an initiating event, is determined retrospectively. This article considers problems of estimation when initiating events occur as a nonhomogeneous Poisson process, and the time s from the initiating event to the final event has pdf f(s) independent of the time of the initiating event. A…

误设的比例风险模型AI 解读

The properties of an estimator based on a proportional hazards model are investigated when the model is incorrect. The estimator from the partial likelihood is shown to be consistent for a parameter that is defined implicitly. The results are used to investigate the effects on estimation if the true model is accelerated failure time, or if covariates are omitted from the proportional hazards model.

Markov 假设下面板数据的分析AI 解读

Methods for the analysis of panel data under a continuous-time Markov model are proposed. We present procedures for obtaining maximum likelihood estimates and associated asymptotic covariance matrices for transition intensity parameters in time homogeneous models, and for other process characteristics such as mean sojourn times and equilibrium distributions. Generalizations to handle covariance analysis and to the fitting of certain nonhomogeneous models are presented, and…

充分性与条件性AI 解读

Ancillary statistics are divided into two logically diatinct types: those determined by the experimental design and those determined by the mathematical modelling of the problem. It ie pointed out that, in the class of inference problems where our purpose is to gain information or insight into the nature of a chance set-up, a weakened conditionality principle when applied first removes the possibility of deriving the likelihood principle. Since to some extent a…

Marginal likelihoods are obtained for the regression parameters in the model presented by Cox (1972). If no ties occur in the recording of failure time data the results of Cox are given a straightforward justification. If ties occur in the data, results different from those suggested by Cox are obtained. Some Monte-Carlo comparisons of these competing results are made. A discrete model is developed for grouped data from Cox's model and estimates of the survivor function are…

似然方法在含大量参数模型中的应用AI 解读

J. D. Kalbfleisch, D. A. Sprott; Application of Likelihood Methods to Models Involving Large Numbers of Parameters, Journal of the Royal Statistical Societ