共查询到20条相似文献,搜索用时 125 毫秒
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本文研究纵向数据下半参数工具变量模型中回归系数的区间估计问题.首先利用B-样条方法逼近半参数模型中的非参数函数.为了处理内生变量和纵向数据的组内相关性,对模型中回归系数提出了基于工具变量和二次推断函数的有效经验对数似然比统计量,并证明所提出统计量渐近服从标准卡方分布,由此构造回归系数的置信域. 相似文献
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构造了有重复观测的部分线性EV模型中的诸多参数估计, 包括回归系数、回归误差方差以及非参数函数估计, 去除了有关经典文献中关于测量误差方差已知的假设. 在一些正则条件下, 证明了所有这些估计都是强相合的, 同时获得了回归系数估计的渐近正态性、非参数函数估计的最优收敛速度. 模拟计算表明这些估计的效果优良. 相似文献
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本文研究纵向数据下非参数部分带有测量误差的部分线性变系数模型的估计.利用B样条函数近似模型中的变系数函数,构造偏差修正的二次推断函数,得到模型中未知参数和变系数函数的估计.证明变系数函数估计量的相合性和参数估计量的渐近正态性.数值模拟和实例分析结果表明所提估计方法在有限样本下的有效性. 相似文献
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本文研究了函数型部分线性乘积模型,该模型可用于响应变量为正数的函数型数据的统计建模问题,经过对数变换后模型转化为函数型部分线性模型.基于B-样条,通过极小化最小一乘相对误差(LARE)和最小乘积相对误差(LPRE),分别给出模型的LARE估计和LPRE估计,其中B-样条基的维数利用Schwarz信息准则选取.对两种估计方法分别给出斜率函数估计的相合性和参数部分估计的渐近正态性,并且证明了斜率函数的收敛率达到了非参数函数估计的最优速率.蒙特卡洛模拟用来比较所提出的方法与最小一乘(LAD)估计和最小二乘(LS)估计在不同误差分布下的有限样本性质,模拟结果表明所提方法是有效和实用的.最后通过一个实际数据分析的例子来说明模型的应用. 相似文献
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二次损失下随机回归系数和参数的线性Minimax估计 总被引:3,自引:0,他引:3
对带有随机效应的一般线性模型,本文提出了随机回归系数和参数线性组合的Minimax估计问题.在二次损失下,研究了线性估计的极小极大性.关于适当的假设,得到了可估函数的唯一线性Minimax估计. 相似文献
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对带有随机效应的一般线性模型,本文提出了随机回归系数和参数线性组合的Minimax估计问题. 在二次损失下,研究了线性估计的极小极大性.关于适当的假设,得到了可估函数的唯一线性Mjnimax 估计. 相似文献
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In some commonly used longitudinal clinical trials designs, the quadratic inference functions (QIF) method fails to work due to non-invertible estimation of the optimal weighting matrix. We propose a modified QIF method, in which the optimal weighting matrix is estimated by a linear shrinkage estimator, replacing the sample covariance matrix. We prove that the linear shrinkage estimator is consistent and asymptotically optimal under the expected quadratic loss, and will have more stable numerical performance than the sample covariance matrix. Simulations show that numerical improvements are acquired in light of a higher percentage of convergence, and smaller standard errors and mean square errors of parameter estimates. 相似文献
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在模型的部分协变量为内生性协变量的情况下,考虑广义变系数模型的一类估计问题.通过结合基函数逼近和一些辅助变量信息,提出了一个基于工具变量的估计过程.并得到了估计的相合性和收敛速度等渐近性质.所提出的估计方法可以有效地消除协变量的内生性对估计精度的影响,并且具有较好的有限样本性质. 相似文献
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《Communications in Nonlinear Science & Numerical Simulation》2011,16(7):2796-2809
Estimation of parameters of nonlinear superimposed sinusoidal signals is an important problem in digital signal processing. In this paper, we consider the problem of estimation of parameters of real valued sinusoidal signals. We propose a real-coded genetic algorithm based robust sequential estimation procedure for estimation of signal parameters. The proposed sequential method is based on elitist generational genetic algorithm and robust M-estimation techniques. The method is particularly useful when there is a large number of superimposed sinusoidal components present in the observed signal and is robust with respect to presence of outliers in the data and impulsive heavy tail noise distributions. Simulations studies and real life signal analysis are performed to ascertain the performance of the proposed sequential procedure. It is observed that the proposed methods perform better than the usual non-robust methods of estimation. 相似文献
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In this paper, the semiparametric generalized partially
linear models (GPLMs) for longitudinal data is studied. We approximate the
nonparametric function in the GPLMs by a regression spline, and use quadratic
inference functions (QIF) to take the within-cluster correlation into account
without involving direct estimation of nuisance parameters in the correlation
matrix. We establish the asymptotic normality of the resulting estimators.
The finite sample performance of the proposed methods is evaluated through
simulation studies and a real data analysis. 相似文献
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This paper investigates the estimation in a class of single-index varying coefficient regression model when some covariates are contaminated with measurement errors. A bias-corrected least square procedure based on the observed data is proposed. By replacing the nonparametric single index part with a local linear approximation, an iterative algorithm for estimating the index parameter is proposed. More importantly, a special case is identified in which the naive procedure provides consistent estimates for the single index parameters. Large sample properties of the proposed estimators are established. The finite sample performance of the proposed estimators are evaluated by simulation studies. 相似文献
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This paper presents an empirical likelihood estimation procedure for parameters of the discretely sampled process of Ornstein-Uhlenbeck type. The proposed procedure is based on the condi- tional characteristic function, and the maximum empirical likelihood estimator is proved to be consistent and asymptotically normal. Moreover, this estimator is shown to be asymptotically efficient under some mild conditions. When the background driving Lévy process is of type A or B, we show that the intensity parameter c... 相似文献
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The covariate-adjusted regression model was initially proposed for
the situations where both the predictors and the response variables are not directly observed,
but are distorted by some common observable covariates. In this paper, we investigate a
covariate-adjusted nonparametric regression (CANR) model and consider the proposed model on
time series setting. We develop a two-step estimation procedure to estimate the regression
function. The asymptotic property of the proposed estimation is investigated under the
-mixing conditions. Both the real data and simulated examples are provided for
illustration. 相似文献
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It is well known that specifying a covariance matrix is difficult in the quantile regression with longitudinal data. This paper develops a two step estimation procedure to improve estimation efficiency based on the modified Cholesky decomposition. Specifically, in the first step, we obtain the initial estimators of regression coefficients by ignoring the possible correlations between repeated measures. Then, we apply the modified Cholesky decomposition to construct the covariance models and obtain the estimator of within-subject covariance matrix. In the second step, we construct unbiased estimating functions to obtain more efficient estimators of regression coefficients. However, the proposed estimating functions are discrete and non-convex. We utilize the induced smoothing method to achieve the fast and accurate estimates of parameters and their asymptotic covariance. Under some regularity conditions, we establish the asymptotically normal distributions for the resulting estimators. Simulation studies and the longitudinal progesterone data analysis show that the proposed approach yields highly efficient estimators. 相似文献
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In this paper, we consider the problem of finding an inner estimation of the solution set of a fuzzy linear system with a real-valued coefficient matrix and a fuzzy-valued right-hand side vector. The proposed idea is based on the utilization of interval Gaussian elimination procedure to produce an inner estimation of the solutions set. To this end, firstly we apply interval Gaussian elimination procedure to obtain the solution set of a fuzzy linear system and secondly, by limiting it via solving a crisp linear system, we find an inner estimation of the solutions set, such that it satisfies the related fuzzy linear system. Finally, several numerical examples are given to show the efficiency and ability of our method. 相似文献