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作者：Zhang, Ying
作者单位：University of Iowa
摘要：We study the nonparametric k-sample test problem with panel count data. The asymptotic normality of a smooth functional of the nonparametric maximum pseudo-likelihood estimator (Wellner & Zhang, 2000) is established under some mild conditions. We construct a class of easy-to-implement nonparametric tests for comparing mean functions of k populations based on this asymptotic normality. We conduct various simulations to validate and compare the tests. The simulations show that the tests perform ...
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作者：Bailey, R. A.; Kunert, J.
作者单位：University of London; Queen Mary University London; Dortmund University of Technology
摘要：There are a number of different models for crossover designs which take account of carryover effects. Since it seems plausible that a treatment with a large direct effect should generally have a larger carryover effect, Kempton et al. (2001) considered a model where the carryover effects are proportional to the direct effects. The advantage of this model lies in the fact that there are fewer parameters to be estimated. Its problem lies in the nonlinearity of the estimators. Kempton et al. (200...
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作者：Green, Peter J.; Mardia, Kanti V.
作者单位：University of Bristol; University of Leeds
摘要：An important problem in shape analysis is to match configurations of points in space after filtering out some geometrical transformation. In this paper we introduce hierarchical models for such tasks, in which the points in the configurations are either unlabelled or have at most a partial labelling constraining the matching, and in which some points may only appear in one of the configurations. We derive procedures for simultaneous inference about the matching and the transformation, using a ...
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作者：Chen, Ming-Hui; Ibrahim, Joseph G.; Shao, Qi-Man
作者单位：University of Connecticut; University of North Carolina; University of North Carolina Chapel Hill; Hong Kong University of Science & Technology
摘要：In this paper, we carry out an in-depth theoretical investigation of Bayesian inference for the Cox regression model. We establish necessary and sufficient conditions for posterior propriety of the regression coefficient, beta, in Cox's partial likelihood, which can be obtained as the limiting marginal posterior distribution of beta through the specification of a gamma process prior for the cumulative baseline hazard and a uniform improper prior for beta. We also examine necessary and sufficie...
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作者：Zeng, Donglin; Lin, D. Y.
作者单位：University of North Carolina; University of North Carolina Chapel Hill
摘要：A class of semiparametric transformation models is proposed to characterise the effects of possibly time-varying covariates on the intensity functions of counting processes. The class includes the proportional intensity model and linear transformation models as special cases. Nonparametric maximum likelihood estimators are developed for the regression parameters and cumulative intensity functions of these models based on censored data. The estimators are shown to be consistent and asymptotical...
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作者：Consonni, G; Leucari, V
作者单位：University of Pavia
摘要：The combination of graphical models and reference analysis represents a powerful tool for Bayesian inference in highly multivariate settings. It is typically difficult to derive reference priors in complex problems. In this paper we present a suitable mixed parameterisation for a discrete decomposable graphical model and derive the corresponding reference prior.
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作者：Huang, JZ; Liu, NP; Pourahmadi, M; Liu, LX
作者单位：Texas A&M University System; Texas A&M University College Station; University of Pennsylvania; Northern Illinois University; Columbia University
摘要：We propose a nonparametric method for identifying parsimony and for producing a statistically efficient estimator of a large covariance matrix. We reparameterise a covariance matrix through the modified Cholesky decomposition of its inverse or the one-step-ahead predictive representation of the vector of responses and reduce the nonintuitive task of modelling covariance matrices to the familiar task of model selection and estimation for a sequence of regression models. The Cholesky factor cont...
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作者：Lee, A. J.; Scott, A. J.; Wild, C. J.
作者单位：University of Auckland
摘要：In a case-augmented study, measurements on a random sample from a population are augmented by information from an independent sample of cases, that is units with some characteristic of interest. We show that inferences about the effect of the covariates on the probability of being a case can be made by fitting a modified prospective likelihood. We also show that this procedure is fully efficient.
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作者：Cheng, Ming-Yen; Hall, Peter; Tu, Dongsheng
作者单位：National Taiwan University; Australian National University; Queens University - Canada; Canadian Cancer Trials Group
摘要：We suggest a completely empirical approach to the construction of confidence bands for hazard functions, based on smoothing the Nelsen-Aalen estimator. In particular, we introduce a local bandwidth-choice method. Our approach uses empirical information about both the survival rate and the censoring rate, and employs undersmoothing to alleviate difficulties caused by bias. We use both Edgeworth expansion and numerical simulation, the former to develop a basic formula and the latter to modify it...
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作者：Jennison, C; Turnbull, BW
作者单位：University of Bath; Cornell University
摘要：Methods have been proposed for redesigning a clinical trial at an interim stage in order to increase power. In order to preserve the type I error rate, methods for unplanned design-change have to be defined in terms of nonsufficient statistics, and this calls into question their efficiency and the credibility of conclusions reached. We evaluate schemes for adaptive redesign, extending the theoretical arguments for use of sufficient statistics of Tsiatis & Mehta (2003) and assessing the possibl...
