有限混合Laplace分布回归模型局部估计的EM算法

本文研究了一类有限混合Laplace分布回归模型的局部极大似然估计问题. 利用核回归方法和最大化局部加权似然函数的EM算法, 获得了参数函数的局部极大似然估计量, 并讨论了它们的渐近偏差, 渐近方差和渐近正态性. 推广了有限混合回归模型下局部非参数估计的结果.     

有限混合Laplace分布回归模型局部估计的EM算法（英文）

本文研究了一类有限混合Laplace分布回归模型的局部极大似然估计问题.利用核回归方法和最大化局部加权似然函数的EM算法,获得了参数函数的局部极大似然估计量,并讨论了它们的渐近偏差,渐近方差和渐近正态性.推广了有限混合回归模型下局部非参数估计的结果.     

半参数回归模型拟极大似然估计的渐近分布

用拟极大似然估计方法研究了误差为AR(1)时间序列的半参数回归模型,得到了参数及非参数的拟极大似然估计量,并研究了它们的渐近分布.     

WEIBULL分布函数形式的选取对参数似然估计的影响

§1.引言参数估计的最重要的方法之一就是Fisher所提出的极大似然方法,极大似然估计量具有我们所期望的一些优良特性.例如,这个估计量是一致估计量和渐近正态的;当样本较大对,一般还是有效估计量;如果它是偏倚的,常可用简单的调节来去掉偏倚性;如果参数θ具有一个充分估计量,则θ的极大似然估计量必然是这个充分估计量的单值函数,如果其反函     

大数据下广义线性模型的参数估计算法

在大数据下,全样本量很大,未知参数极大似然估计的计算变得十分困难.文章主要对于广义线性模型参数的极大似然估计研究一种有效的计算方法.首先证明了随机抽样算法下的估计量的渐近正态性,由此提出了入样概率的选取准则及两步随机抽样算法.模拟研究表明,绝大部分情况下,运用文章提出的方法所得到广义线性模型极大似然估计量的均方误差低于与之对比的简单随机抽样.     

一种惩罚最大似然方法估计混合回归模型

本文考虑具有正态误差假设下混合回归模型的参数估计问题.由于似然函数的无界性,混合回归模型普通的最大似然估计不存在.本文提出一种惩罚最大似然方法来估计混合回归模型的参数,证明惩罚最大似然估计量(penalized maximum likelihood estimation, PMLE)具有强相合和渐近正态性.通过深入模拟研究,从估计精确性角度看,惩罚最大似然估计量有很好的表现.本文还给出一个音调感知的例子来说明理论结果的应用.     

利用样本分位数的Logistic总体分布参数的近似最佳线性无偏估计

Harter H_L.,Balakrishnan N.等先后讨论了Logistic总体分布参数的极大似然估计,近似极大似然估计;其后Ogawa J.,Lloyd E.H.,Kulldorff G.,Gupta S.S,及chan L.K. 等又先后讨论了Logistlic分布参数的最佳线性无偏估计及估计的相对效率等问题.令人遗憾的是:在大样本情形下,上述估计均难以求得.为缓解这一困难,本文讨论利用样本分位数的Logistic总体的近似最佳线性无偏估计,给出估计量的大样本性质,以及样本分位数不超过10情形下,估计量有渐近最大相对估计效率时样本分位数的选取方案等.     

Pareto分布在逐步Ⅱ型区间删失下的参数估计

本文研究Pareto分布在逐步Ⅱ型区间删失的情形下参数的估计和性质,给出了参数的极大似然估计及其Newton-Raphson求解算法,并证明了在一定条件下极大似然估计的相合性及渐近正态性.     

非线性半参数回归模型的最大经验似然估计

对于非线性半参数回归模型的估计问题,利用经验似然方法,给出了回归系数,光滑函数以及误差方差的最大经验似然估计.在一定条件下证明了所得估计量的渐近正态性和相合性.     

变量为区间截断数据时回归模型的参数估计(英文)

在假设自变量X的分布为离散未知分布且样本为区间截断数据而因变量Y是可观察的情况下,利用EM方法得到了回归参数的极大似然估计,在一定的条件下估计量的分布为渐近正态的.     

Pareto�ֲ�����II������ɾʧ�µIJ�������

??In this paper, we concern with the estimation problem for the Pareto distribution based on progressive Type-II interval censoring with random removals. We discuss the maximum likelihood estimation of the model parameters. Then, we show the consistency and asymptotic normality of maximum likelihood estimators based on progressive Type-II interval censored sample.     

��I�ͻ�Ͻ�β��ָ��——�������ֲ�����ʧЧģ�͵�ͳ�Ʒ���

In this paper, we investigate a competing risks model based on exponentiated Weibull distribution under Type-I progressively hybrid censoring scheme. To estimate the unknown parameters and reliability function, the maximum likelihood estimators and asymptotic confidence intervals are derived. Since Bayesian posterior density functions cannot be given in closed forms, we adopt Markov chain Monte Carlo method to calculate approximate Bayes estimators and highest posterior density credible intervals. To illustrate the estimation methods, a simulation study is carried out with numerical results. It is concluded that the maximum likelihood estimation and Bayesian estimation can be used for statistical inference in competing risks model under Type-I progressively hybrid censoring scheme.     

Statistics of the three-parameter weibull distribution

We consider the estimation of the parameters of the three-parameter Weibull distribution, with particular emphasis on the unknown endpoint of the distribution. We summarize recent results on the asymptotic behaviour of maximum likelihood estimators. We continue with an example in which maximum likelihood and Bayesian estimators arc compared. We conclude that there are practical advantages to the Bayesian approach, but the study also suggests ways in which the maximum likelihood analysis may be improved.     

Asymptotic efficiency of the two-stage estimation method for copula-based models

For multivariate copula-based models for which maximum likelihood is computationally difficult, a two-stage estimation procedure has been proposed previously; the first stage involves maximum likelihood from univariate margins, and the second stage involves maximum likelihood of the dependence parameters with the univariate parameters held fixed from the first stage. Using the theory of inference functions, a partitioned matrix in a form amenable to analysis is obtained for the asymptotic covariance matrix of the two-stage estimator. The asymptotic relative efficiency of the two-stage estimation procedure compared with maximum likelihood estimation is studied. Analysis of the limiting cases of the independence copula and Fréchet upper bound help to determine common patterns in the efficiency as the dependence in the model increases. For the Fréchet upper bound, the two-stage estimation procedure can sometimes be equivalent to maximum likelihood estimation for the univariate parameters. Numerical results are shown for some models, including multivariate ordinal probit and bivariate extreme value distributions, to indicate the typical level of asymptotic efficiency for discrete and continuous data.     

Estimating the parameters of Weibull distribution and the acceleration factor from hybrid partially accelerated life test

This article considers the estimation of parameters of Weibull distribution based on hybrid censored data. The parameters are estimated by the maximum likelihood method under step-stress partially accelerated test model. The maximum likelihood estimates (MLEs) of the unknown parameters are obtained by Newton–Raphson algorithm. Also, the approximate Fisher information matrix is obtained for constructing asymptotic confidence bounds for the model parameters. The biases and mean square errors of the maximum likelihood estimators are computed to assess their performances through a Monte Carlo simulation study.     

双边定时截尾样本下广义逆指数分布形状参数的估计

先给出了广义逆指数分布在双边定时截尾样本下形状参数的最大似然估计,并不能得到估计的显式表达式,但证明了参数在(0,+∞)上最大似然估计是唯一存在的.其次提出用EM算法求出形状参数的估计且该估计具有良好的收敛性,还给出了形状参数的EM估计的渐近方差和近似置信区间;最后通过数值模拟,对形状参数的最大似然估计和EM估计的效果进行了比较,说明了用EM算法求形状参数的估计是可行的,并且模拟效果相对比较好.     

Robust Estimation of the Generalized Pareto Distribution

One approach used for analyzing extremes is to fit the excesses over a high threshold by a generalized Pareto distribution. For the estimation of the shape and scale parameters in the generalized Pareto distribution, under some restrictions on the value of the scale parameter, maximum likelihood, method of moments and probability weighted moments' estimators are available. However, these are not robust estimators. In this paper we implement a robust estimation procedure known as the method of medians (He and Fung, 1999) to estimate the parameters in the generalized Pareto distribution. The asymptotic distribution of our estimator is normal for any value of the shape parameter except –1.     

具有缺失数据的两个伽马分布总体参数的估计与假设检验

主要在数据缺失的情况下研究了伽马分布的参数估计与假设检验,位置参数已知的条件下,给出形状参数的极大似然估计,并证明了形状参数估计的强相合性与渐进正态性,并对两总体参数之差的置信区间和假设检验做出分析,最后做随机模拟验证了其合理性.     

On goodness-of-fit and the bootstrap

The empirical process, where unknown parameters of the underlying distribution function are estimated by bootstrap methods, is considered. It is approximated by a sequence of Gaussian process. In the maximum likelihood estimation case it converges to a Brownian Bridge. The asymptotic distribution of Cramér-von Mises, Anderson-Darling and Kolmogorov-Smirnov test statistics are derived.     

The EM algorithm for ML Estimators under nonlinear inequalities restrictions on the parameters

One of the most powerful algorithms for obtaining maximum likelihood estimates for many incomplete-data problems is the EM algorithm. However, when the parameters satisfy a set of nonlinear restrictions, It is difficult to apply the EM algorithm directly. In this paper,we propose an asymptotic maximum likelihood estimation procedure under a set of nonlinear inequalities restrictions on the parameters, in which the EM algorithm can be used. Essentially this kind of estimation problem is a stochastic optimization problem in the M-step. We make use of methods in stochastic optimization to overcome the difficulty caused by nonlinearity in the given constraints.