一类泛函的非参数Bayes和经验Bayes估计的渐近结构

本文我们讨论了一类泛函的非参数Bayes和经验Bayes估计的渐近结构。在适当条件下,我们证得了Bayes和经验Bayes估计的渐近分布是正态的。     

最大似然方法和Bayes方法在结构方程模型分析中的讨论(英文)

本文通过模拟研究,讨论了最大似然方法和Bayes方法在分析结构方程模型中的相似点和不同之处。     

指数分布参数多层Bayes和E Bayes估计的性质

本文讨论无失效数据下指数分布参数多层Bayes估计和E Bayes估计的性质,在超参数分别取两种不同的先验分布下,证明参数的多层Bayes估计和E Bayes估计渐近相等,且多层Bayes估计值小于E Bayes估计值.     

均匀分布族 U(0,θ)中经验 Bayes 检验的渐近特征

关于经验 Bayes 检验的研究,目前在文献上能见到一些结果,其中部分是讨论经验Bayes 检验的渐近最优性及其收敛速度,参见[1—4,6,7,9];最近 stijnen 讨论了连续型单参数指数族中经验 Bayes 检验的条件 Bayes 风险的渐近分布,从而得到了精确的收敛速度.本文我们将讨论均匀分布族{U(0,θ),θ>0)中经验 Bayes 检验的条件 Bayes 风险的极限分布,从而得到了经验 Bayes 检验的渐近最优性及其收敛速度.     

相依非线性回归系统中的附加信息Bayes拟似然

对多个相依统计模型的研究,现有成果主要集中在相依线性回归系统.本文则首次提出多个相依非线性回归系统中的附加信息Bayes拟似然,给出误差相关信息和先验信息在拟似然中的迭加方法,在较弱的条件下得到附加信息Bayes拟似然的一些性质,在Bayes风险准则下。讨论了其估计函数和参数估计的最优性,证明了附加信息Bayes拟似然的渐近 Bayes风险随着相依信息的增力。而逐步减少.     

一类均匀分布在绝对值损失下的渐近最优经验Bayes估计

关于平方损失下的经验 Bayes 估计问题,文献中已有较多的结果.而对于绝对值损失,由于参数的 Bayes 估计不易用样本的边缘分布表达出来,从而难于构造经验 Bayes 估计.本文试图越过这一难点,讨论一类均匀分布,给出其参数的经验 Bayes 估计的渐近最优性.本文讨论写成下述形状的均匀分布族     

错误指定多元线性回归模型的Bayes估计

本文在错误指定下给出了多元线性模型的最优线性 Bayes估计 ,在矩阵损失下讨论了其相对于最小二乘法估计的优良性 ,且获得 Bayes估计的容许性和极小极大性     

Pareto分布参数的经验Bayes检验的收敛速度:NA样本情形

本文讨论了NA(negativeassociation)样本情形Pareto分布参数的经验Bayes(EB)单侧和双侧检验问题.利用概率密度函数的核估计构造了参数的经验Bayes检验函数,在适当的条件下证明了所提出的经验Bayes检验函数的渐近最优(a.o.)性并获得了其收敛速度.     

具有测量误差的非线性模型的Bayes估计

测量中大量的函数模型都是非线性回归模型．当回归变量含有一定的测量误差时，我们得到非线性测量误差模型．本讨论了这种模型中未知参数具有正态先验分布时的参数Bayes估计方法，并对这种估计进行了影响分析，证明了删除模型与均值漂移模型中参数的Bayes估计相同，利用Cook统计量给出了删除模型下参数的Bayes估计的影响度量．     

分组数据的Bayes分析—Gibbs抽样方法

分组数据是可靠性试验中常见的一类不完全数据，由于似然函数比较复杂使Bayes分析很困难。本文利用Gibbs抽样方法，对分组数据的Bayes分析就容易实现，在寿命分布是威布尔分布情形，本文还给出了Gibbs抽样和Metropolis算法杂合的抽样方法，最后还讨论了Gibbs抽样方法的一些特点，并通过一些模拟结果对现有的几种处理分组数据的方法进行了比较。     

ASSESSING LOCAL PRIOR INFLUENCE IN BAYESIAN ANALYSIS

ＡＳＳＥＳＳＩＮＧＬＯＣＡＬＰＲＩＯＲＩＮＦＬＵＥＮＣＥＩＮＢＡＹＥＳＩＡＮＡＮＡＬＹＳＩＳ￥ＳＨＩＨＪＩＡＮＱＩＮＧＡｂｓｔｒａｃｔ：Ａｇｅｎｅｒａｌｍｅｔｈｏｄｆｏｒａｓｓｅｓｓｉｎｇｌｏｃａｌｉｎｆｌｕｅｎｃｅｏｆｍｉｎｏｒｐｅｒｔｕｒｂａｔｉ...     

具有Rao简单结构的多元T-模型的局部影响分析

本文应用以Kullback-Leibler散度为基础的Bayesian局部影响方法，对具有Rao简单结构的多元T-模型进行了局部影响分析．在确定了先验分布假设下，详细地研究了这个模型的Bayesian Hessian矩阵，作为应用，特别考虑了常见的加权协方差扰动形式．     

BAYESIAN LOCAL INFLUENCE ASSESSMENTS IN A GROWTH CURVE MODEL WITH GENERAL COVARIANCE STRUCTURE

1 IntroductionThe problem of how to deal With local influence assessment in a growth curve model withgeneral covariance structure is very important. There are two main reasons why this is so. First,although the growth curve model can be viewed as a generalizetion of classical linear regressionmodel in some wad, as pointed out by for etc.[1], two models are substantially different andthe former is much more complicated than the latter. Secondly3 it is not generally the case withlocally influen…     

Assessment of local influence on Cox’s proportional hazards model

The second order approach of local influence (see [15]) is developed and applied to Cox’s proportional hazards model, and compared with Cook's local influence approach (see [6] and [13]) which was used in this model. To study local influence, we perturb not only all cases simultaneously, but also cases individually to obtain “direction curvature” in directionl and “curvature” for single case. Some examples are used to illustrate these methods. This work is supported by the Youth Science Foundation of Peking University and a research grant from State Educational Committee     

Case Influence Analysis in Bayesian Inference

Abstract

We demonstrate how case influence analysis, commonly used in regression, can be applied to Bayesian hierarchical models. Draws from the joint posterior distribution of parameters are importance weighted to reflect the effect of deleting each observation in turn; the ensuing changes in the posterior distribution of each parameter are displayed graphically. The procedure is particularly useful when drawing a sample from the posterior distribution requires extensive calculations (as with a Markov Chain Monte Carlo sampler). The structure of hierarchical models, and other models with local dependence, makes the importance weights inexpensive to calculate with little additional programming. Some new alternative weighting schemes are described that extend the range of problems in which reweighting can be used to assess influence. Applications to a growth curve model and a complex hierarchical model for opinion data are described. Our focus on case influence on parameters is complementary to other work that measures influence by distances between posterior or predictive distributions.     

纵向数据下半参数联合均值协方差模型的贝叶斯分析

基于改进的Cholesky分解,研究分析了纵向数据下半参数联合均值协方差模型的贝叶斯估计和贝叶斯统计诊断,其中非参数部分采用B样条逼近.主要通过应用Gibbs抽样和Metropolis-Hastings算法相结合的混合算法获得模型中未知参数的贝叶斯估计和贝叶斯数据删除影响诊断统计量.并利用诊断统计量的大小来识别数据的异常点.模拟研究和实例分析都表明提出的贝叶斯估计和诊断方法是可行有效的.     

Adaptive Rejection Metropolis Simulated Annealing for Detecting Global Maximum Regions

A finite mixture model has been used to fit the data from heterogeneous populations to many applications. An Expectation Maximization (EM) algorithm is the most popular method to estimate parameters in a finite mixture model. A Bayesian approach is another method for fitting a mixture model. However, the EM algorithm often converges to the local maximum regions, and it is sensitive to the choice of starting points. In the Bayesian approach, the Markov Chain Monte Carlo (MCMC) sometimes converges to the local mode and is difficult to move to another mode. Hence, in this paper we propose a new method to improve the limitation of EM algorithm so that the EM can estimate the parameters at the global maximum region and to develop a more effective Bayesian approach so that the MCMC chain moves from one mode to another more easily in the mixture model. Our approach is developed by using both simulated annealing (SA) and adaptive rejection metropolis sampling (ARMS). Although SA is a well-known approach for detecting distinct modes, the limitation of SA is the difficulty in choosing sequences of proper proposal distributions for a target distribution. Since ARMS uses a piecewise linear envelope function for a proposal distribution, we incorporate ARMS into an SA approach so that we can start a more proper proposal distribution and detect separate modes. As a result, we can detect the maximum region and estimate parameters for this global region. We refer to this approach as ARMS annealing. By putting together ARMS annealing with the EM algorithm and with the Bayesian approach, respectively, we have proposed two approaches: an EM-ARMS annealing algorithm and a Bayesian-ARMS annealing approach. We compare our two approaches with traditional EM algorithm alone and Bayesian approach alone using simulation, showing that our two approaches are comparable to each other but perform better than EM algorithm alone and Bayesian approach alone. Our two approaches detect the global maximum region well and estimate the parameters in this region. We demonstrate the advantage of our approaches using an example of the mixture of two Poisson regression models. This mixture model is used to analyze a survey data on the number of charitable donations.     

Adaptive Bayesian Nonstationary Modeling for Large Spatial Datasets Using Covariance Approximations

Gaussian process models have been widely used in spatial statistics but face tremendous modeling and computational challenges for very large nonstationary spatial datasets. To address these challenges, we develop a Bayesian modeling approach using a nonstationary covariance function constructed based on adaptively selected partitions. The partitioned nonstationary class allows one to knit together local covariance parameters into a valid global nonstationary covariance for prediction, where the local covariance parameters are allowed to be estimated within each partition to reduce computational cost. To further facilitate the computations in local covariance estimation and global prediction, we use the full-scale covariance approximation (FSA) approach for the Bayesian inference of our model. One of our contributions is to model the partitions stochastically by embedding a modified treed partitioning process into the hierarchical models that leads to automated partitioning and substantial computational benefits. We illustrate the utility of our method with simulation studies and the global Total Ozone Matrix Spectrometer (TOMS) data. Supplementary materials for this article are available online.     

Effective dimensions of partially observed polytrees

Model complexity is an important factor to consider when selecting among Bayesian network models. When all variables are observed, the complexity of a model can be measured by its standard dimension, i.e., the number of linearly independent network parameters. When latent variables are present, however, standard dimension is no longer appropriate and effective dimension should be used instead [Proc. 12th Conf. Uncertainty Artificial Intell. (1996) 283]. Effective dimensions of Bayesian networks are difficult to compute in general. Work has begun to develop efficient methods for calculating the effective dimensions of special networks. One such method has been developed for partially observed trees [J. Artificial Intell. Res. 21 (2004) 1]. In this paper, we develop a similar method for partially observed polytrees.     

Local adaptive smoothing in kernel regression estimation

We consider nonparametric estimation of a smooth function of one variable. Global selection procedures cannot sufficiently account for local sparseness of the covariate nor can they adapt to local curvature of the regression function. We propose a new method for selecting local smoothing parameters which takes into account sparseness and adapts to local curvature. A Bayesian type argument provides an initial smoothing parameter which adapts to the local sparseness of the covariate and provides the basis for local bandwidth selection procedures which further adjust the bandwidth according to the local curvature of the regression function. Simulation evidence indicates that the proposed method can result in reduction of both pointwise mean squared error and integrated mean squared error.