共查询到19条相似文献，搜索用时 125 毫秒
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邹小云 《赤峰学院学报(自然科学版)》2013,(23):8-10
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． 相似文献
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徐晨 《中国校外教育(理论)》2014,(27):118
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。 相似文献
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本文基于模糊变量的可信性分布,提出了模糊极大似然估计的概念,证明了模糊极大似然估计的不变性及其收敛性。 相似文献
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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。 相似文献
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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． 相似文献
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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。 相似文献
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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. 相似文献
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探讨了基于充分统计量的几个重要应用,重点讨论了充分统计量在参数估计中一致最小方差无偏估计和极大似然估计的构造方法及在假设检验中检验函数的构造方法。 相似文献
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This article compares maximum likelihood and Bayesian estimation of the correlated trait–correlated method (CT–CM) confirmatory factor model for multitrait–multimethod (MTMM) data. In particular, Bayesian estimation with minimally informative prior distributions—that is, prior distributions that prescribe equal probability across the known mathematical range of a parameter—are investigated as a source of information to aid convergence. Results from a simulation study indicate that Bayesian estimation with minimally informative priors produces admissible solutions more often maximum likelihood estimation (100.00% for Bayesian estimation, 49.82% for maximum likelihood). Extra convergence does not come at the cost of parameter accuracy; Bayesian parameter estimates showed comparable bias and better efficiency compared to maximum likelihood estimates. The results are echoed via 2 empirical examples. Hence, Bayesian estimation with minimally informative priors outperforms enables admissible solutions of the CT–CM model for MTMM data. 相似文献
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FREDERIC M. LORD 《Journal of Educational Measurement》1986,23(2):157-162
Advantages and disadvantages of joint maximum likelihood, marginal maximum likelihood, and Bayesian methods of parameter estimation in item response theory are discussed and compared. 相似文献
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In this study we compared five item selection procedures using three ability estimation methods in the context of a mixed-format adaptive test based on the generalized partial credit model. The item selection procedures used were maximum posterior weighted information, maximum expected information, maximum posterior weighted Kullback-Leibler information, and maximum expected posterior weighted Kullback-Leibler information procedures. The ability estimation methods investigated were maximum likelihood estimation (MLE), weighted likelihood estimation (WLE), and expected a posteriori (EAP). Results suggested that all item selection procedures, regardless of the information functions on which they were based, performed equally well across ability estimation methods. The principal conclusions drawn about the ability estimation methods are that MLE is a practical choice and WLE should be considered when there is a mismatch between pool information and the population ability distribution. EAP can serve as a viable alternative when an appropriate prior ability distribution is specified. Several implications of the findings for applied measurement are discussed. 相似文献
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基于二项分布B(n,p)总体,给出了未知参数p2的矩估计和极大似然估计,并讨论了估计量的无偏性。 相似文献
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Allan S. Cohen Seock-Ho Kim Michael J. Subkoviak 《Journal of Educational Measurement》1991,28(1):49-59
Detection of differential item functioning (DIF) on items intentionally constructed to favor one group over another was investigated on item parameter estimates obtained from two item response theory-based computer programs, LOGIST and BILOG. Signed- and unsigned-area measures based on joint maximum likelihood estimation, marginal maximum likelihood estimation, and two marginal maximum a posteriori estimation procedures were compared with each other to determine whether detection of DIF could be improved using prior distributions. Results indicated that item parameter estimates obtained using either prior condition were less deviant than when priors were not used. Differences in detection of DIF appeared to be related to item parameter estimation condition and to some extent to sample size. 相似文献
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Error indices (bias, standard error of estimation, and root mean squared error) obtained on different measurement scales under different test-termination rules in computerized adaptive testing (CAT) were examined. Four ability estimation methods (maximum likelihood estimation, weighted likelihood estimation, expected a posterior, and maximum a posterior), three measurement scales (θ, number-correct score, and ACT score), and three test-termination rules (fixed length, fixed standard error, and target information) were studied for a real and a generated item pool. The findings indicated that the amount and direction of bias, standard error of estimation, and root mean squared error obtained under different ability estimation methods were influenced both by scale transformations and by test-termination rules in a CAT environment. The implications of these effects for testing programs are discussed. 相似文献
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对给定容量为n的线性指数分布样本X1,X2,…,Xn,在Linex损失函数下,利用共轭先验分布讨论线性指数分布参数θ的Bayes估计,多层Bayes估计,E-Bayes估计和极大似然估计. 相似文献