极大似然估计的性质探讨

文章首先介绍了极大似然估计,然后综述了极大似然估计的优良性质,同时探讨了在应用极大似然估计时所应注意的问题。     

极大似然估计及其应用

讨论了极大似然估计原理及求法,说明了极大似然估计在不同分布和参数空间的应用,阐述了生命表中在单风险非完整样本数据环境中表格生存模型的极大似然估计方法．     

基于EM算法实现混合密度极的大似然参数估计

在介绍极大似然估计与EM算法的基础上,探讨了基于EM算法的两混合正态分布极大似然参数估计,并举例说明了若干经典场合的极大似然估计的算法．     

双边定数截尾下线性指数分布的参数估计

在双边定数截尾样本下讨论了线性指数分布中未知参数的极大似然估计和Bayes估计.通过Newton-Raphson迭代法得到了参数的极大似然估计,并证明了极大似然估计的唯一存在性.选取无信息先验分布与共轭先验分布,分别在对称损失函数和非对称损失函数下,通过Tierney-Kadane近似讨论参数的Bayes近似估计.利用MatlabR200b模拟了未知参数的极大似然估计的均方误差以及Bayes估计的均方误差,结果表明：不同样本量不同截尾方案下,选取Gamma先验分布并在平方损失函数下,未知参数的Bayes估计的均方误差是最小的.     

等价限制线性模型中极大似然估计的稳健性

稳健性分析是判断估计值与真实值之间差异是否重要的一种方法。限制线性模型下的极大似然估计的稳健性是当前大家比较感兴趣的一个问题。笔者在前人的基础上,给出限制线性模型中极大似然估计对随机误差协方差矩阵的稳健性统计量,并对其进行分析,得出限制线性模型中极大似然估计对随机误差协方差矩阵不敏感。     

一类单参数均匀分布上参数极大似然估计及优良性的讨论

文中对U={θ-1/2,θ＋1/2}上参数θ常用的三个极大似然估计及修正后的极大似然估计,从均方误差角度进行比较,得出了较优的估计,并证明其相合性及UMVUE．     

大学数理统计教学中有关极大似然估计方法的课堂讲授

极大似然估计在参数的点估计方法中是一个重要的估计方法,并且其估计值有很多优良的统计性质。在教学中,由于此方法计算较为复杂,学生学习起来较为困难。主要介绍了极大似然估计的容易理解的课堂讲授方法。     

逐步二型删失数据下广义Pareto分布的参数估计

逐步二型删失数据在生存分析中的应用较为广泛,因此在逐步二型删失数据下推导了广义Pareto分布中的尺度参数的极大似然估计与Bayes估计的估计形式,并在平方损失函数下,基于MCMC方法与Lindley近似法,给出了广义Pareto分布尺度参数的Bayes估计.结果表明：贝叶斯估计方法优于极大似然估计方法,MCMC后验抽样下的Bayes估计优于Lindley近似方法.     

经验似然在正态分布中的应用

正态分布为概率论中很重要的一种分布,在科学研究中有着重要的地位,该分布由均值和方差两个变量决定。常用的参数估计法为矩法估计和极大似然估计,经验似然作为一种新的估计方法,同样适用于其它常用的分布。     

基于最大L_q似然估计的广义非线性模型的统计诊断(英文)

为了检测数据是否符合给定的模型,需要对数据进行统计诊断.研究了基于最大Lq似然估计的广义非线性模型的统计诊断问题.利用3个统计诊断量来检验数据中是否都存在异常点.模拟结果显示,当样本容量较小时,使用最大Lq似然估计方法得到的诊断统计量的结果要比使用极大似然估计(MLE)方法得到的结果大;随着样本容量的增加,它们之间的区别逐渐减小.因此,使用最大Lq似然估计方法比用MLE方法更容易找到数据中的异常点.     

对数正态分布参数的最大似然估计

利用最大似然估计法求出了对数正态分布两个参数的估计量，并讨论了它们的无偏性和相合性。     

Strong Consistency of Reliability Estimators for Multiple-Component Measuring Instruments

It is shown that the maximum likelihood estimator of the widely used omega coefficient for reliability of multicomponent measuring instruments converges almost surely to the population reliability coefficient for normal congeneric measures with uncorrelated errors as sample size increases indefinitely. This strong consistency implies convergence in probability (consistency) as well as in distribution for the omega estimator. Strong consistency is also demonstrated for the maximal reliability estimator associated with the optimal linear combination of the instrument components. The findings of this note add (i) to the recommendation to use in the general normality case the omega estimator in empirical research, (ii) to the critical literature on the popular coefficient alpha then, and (iii) to the literature on the properties of the optimal linear combination of observed measures and the maximal reliability estimator.     

A Primer on Maximum Likelihood Algorithms Available for Use With Missing Data

Maximum likelihood algorithms for use with missing data are becoming commonplace in microcomputer packages. Specifically, 3 maximum likelihood algorithms are currently available in existing software packages: the multiple-group approach, full information maximum likelihood estimation, and the EM algorithm. Although they belong to the same family of estimator, confusion appears to exist over the differences among the 3 algorithms. This article provides a comprehensive, nontechnical overview of the 3 maximum likelihood algorithms. Multiple imputation, which is frequently used in conjunction with the EM algorithm, is also discussed.     

逐步Ⅱ型寿命下逆Rayleigh分布参数的估计

在逐步Ⅱ型截尾样本下讨论了逆Rayleigh分布参数的估计问题,给出了参数的最大似然估计,并在三种不同的损失函数下给出了参数的Bayes估计和区间估计.最后给出了数值模拟的例子。     

Maximum power point tracking of a photovoltaic energy system using neural fuzzy techniques

In order to improve the output efficiency of a photovoltaic (PV) energy system, the real-time maximum power point (MPP) of the PV array should be tracked closely. The non-linear and time-variant characteristics of the photovoltaic array and the non-linear and non-minimum phase characteristics of a boost converter make it difficult to track the MPP as in traditional control strategies. A neural fuzzy controller (NFC) in conjunction with the reasoning capability of fuzzy logical systems and the learning capability of neural networks is proposed to track the MPP in this paper. A gradient estimator based on a radial basis function neural network is developed to provide the reference information to the NFC. With a derived learning algorithm, the parameters of the NFC are updated adaptively. Experimental results show that, compared with the fuzzy logic control algorithm, the proposed control algorithm provides much better tracking performance.     

H-Likelihood Approach to Factor Analysis for Ordinal Data

Marginal likelihood-based methods are commonly used in factor analysis for ordinal data. To obtain the maximum marginal likelihood estimator, the full information maximum likelihood (FIML) estimator uses the (adaptive) Gauss–Hermite quadrature or stochastic approximation. However, the computational burden increases rapidly as the number of factors increases, which renders FIML impractical for large factor models. Another limitation of the marginal likelihood-based approach is that it does not allow inference on the factors. In this study, we propose a hierarchical likelihood approach using the Laplace approximation that remains computationally efficient in large models. We also proposed confidence intervals for factors, which maintains the level of confidence as the sample size increases. The simulation study shows that the proposed approach generally works well.     

Using Instrumental Variables to Estimate the Parameters in Unconditional and Conditional Second-Order Latent Growth Models

This article applies Bollen’s (1996) 2-stage least squares/instrumental variables (2SLS/IV) approach for estimating the parameters in an unconditional and a conditional second-order latent growth model (LGM). First, the 2SLS/IV approach for the estimation of the means and the path coefficients in a second-order LGM is derived. An empirical example is then used to show that 2SLS/IV yields estimates that are similar to maximum likelihood (ML) in the estimation of a conditional second-order LGM. Three subsequent simulation studies are then presented to show that the new approach is as accurate as ML and that it is more robust against misspecifications of the growth trajectory than ML. Together, these results suggest that 2SLS/IV should be considered as an alternative to the commonly applied ML estimator.     

双向截尾情况下最大似然估计的渐近正态性

本文讨论了左截断右删失情况下最大似然估计的大样本性质,在一定的条件下证明了最大似然估计具有渐近正态性.     

Five Methods for Estimating Angoff Cut Scores with IRT

This article illustrates five different methods for estimating Angoff cut scores using item response theory (IRT) models. These include maximum likelihood (ML), expected a priori (EAP), modal a priori (MAP), and weighted maximum likelihood (WML) estimators, as well as the most commonly used approach based on translating ratings through the test characteristic curve (i.e., the IRT true‐score (TS) estimator). The five methods are compared using a simulation study and a real data example. Results indicated that the application of different methods can sometimes lead to different estimated cut scores, and that there can be some key differences in impact data when using the IRT TS estimator compared to other methods. It is suggested that one should carefully think about their choice of methods to estimate ability and cut scores because different methods have distinct features and properties. An important consideration in the application of Bayesian methods relates to the choice of the prior and the potential bias that priors may introduce into estimates.     

两个0-1总体具有部分缺失数据时的估计和检验

文章主要讨论了两个0-1总体均具有部分缺失数据时的参数的极大似然估计,并证明了估计的强相合性和渐进正态性,给出了大样本场合下的似然比检验统计量的极限分布。