线性相关模型中误差方差的经验似然估计及其Bootstrap

该文利用经验似然方法，对线性相关模型中误差方差的传统最小二乘型估计进行修正，得到的修正估计其渐近方差比传统估计的更小．同时，我们还讨论了修正估计的Bootstrap逼近问题．关键词##4相关模型;;误差方差;;最小二乘;;经验似然;;Bootstrap．     

非线性模型误差方差估计的Bootstrap逼近和分布的收敛速度

本文对非线性模型误差方差的估计基于Jackknife虚拟值的Bootstrap方法建立了Bootstrap逼近,证明了逼近的相合性定理,得到了逼近的速度是o(n~(-1/2))。进一步,本文证明了误差方差估计的分布以理想的最佳速度o(n~(-1/2))收敛于正态分布的结论。     

关于线性模型误差方差估计的Bootstrap逼近的一点注记

[3]对线性模型误差方差的估计建立了Bootstrap逼近。本文用另一种方法对此估计建立了Bootstrap逼近,证明了逼近的相合性定理,得到了逼近的速度达到o(n~(- 1/2))的结论。     

概率密度函数核估计的Bootstrap逼近

主要研究了密度函数核估计逼近的速度,用Bootstrap方法对核密度进行估计,在适当的条件下,进一步提高了密度核估计Bootstrap逼近的速度,所得到的结果使得密度核估计Bootstrap逼近的速度与密度函数及其导数之间的关系更加的明确.     

重尾分布的尾部指数估计及沪深股市实证分析

重尾分布尾部指数α的估计依赖于样本中所用顺序统计量个数k的选取.本文介绍了估计α时选择k的两类不同的方法:Sum-plot方法和Bootstrap方法,并对Hall提出的Bootstrap方法作了改进,称为M-Bootstrap方法.本文利用上述方法对已知分布进行Monte-Carlo模拟,研究它们的可行性,然后对上海和深圳两市股指数据进行了实证分析.计算结果表明,上海和深圳股指收益率具有重尾性.是右偏态的,右尾厚于左尾.通过几种方法计算的结果比较发现Sum-plot方法和M-Bootstrap方法在估计重尾指数上精确性较高一些,而且不受异常值的影响.     

GARCH模型估计方法选择及对上证指数的应用

本文介绍了对ARCH/GARCH模型的两种估计方法:准极大似然估计和极小绝对偏差估计,并提出了一种基于自助法(Bootstrap)对估计方法的选择。在厚尾程度不同的情况下进行了模拟分析,表明对于一个具体的数据,该选择法能够自动选择较优的估计方法。并用该方法对上海证券交易所A股和B股的股价指数进行了分析,印证了上海股市B股收益率的尾部厚于A股收益率尾部。     

右删失情形下平均生存时间的加权Bootstrap推断

在右删失情形下,基于一类合成数据,采用加权Bootstrap方法获得了平均生存时间的加权Bootstrap估计及其加权Bootstrap分布,并就权重是否独立两种情形,证明了此估计的相合性及此分布近似的有效性.基于此,构造了平均生存时间的置信区间.在数值模拟中,取权为Dirichlet(n;1,…,1),并从覆盖概率和区间长度角度,比较了加权Bootstrap和渐近正态逼近产生的置信区间.     

部分线性单指标模型的M-估计

单指标模型是一类非常重要的半参数回归模型,不仅可以降低数据维数,克服多元数据中的"维数祸根"问题,而且能抓住高维数据的主要特征.文章研究部分线性单指标模型的M-估计,利用B-样条近似技术逼近非参数函数,提出了获得模型中未知参数M-估计的方法,在一些正则条件下,研究了回归函数以及回归系数的M-估计的渐近性质.随机模拟结果表明了文中M-估计具有稳健性.     

线性模型中随机加权自助法的大样本研究 *

讨论了逼近线性模型中M估计分布的随机加权自助法 ,在一般的条件下证明了这种方法的强有效性 .     

一类有渐近展开的分布的独立和逼近

Efron 于1979年提出了 Bootstrap 方法,随后郑忠国在[2]中应用随机加权的思想,推广了 Efron 的方法.随着理论研究和实际应用的深入,Bootstrap 方法已引起了统计工作者越来越广泛的注意.对于分布的估计问题,在很多情况下已证实了随机加权逼近比通常的正态逼近更为精密,显示出随机加权法的优越性.例如,对测量模型     

Data-driven local bandwidth selection for additive models with missing data

This paper deals in the nonparametric estimation of additive models in the presence of missing data in the response variable. Specifically in the case of additive models estimated by the Backfitting algorithm with local polynomial smoothers [1]. Three estimators are presented, one based on the available data and two based on a complete sample from imputation techniques. We also develop a data-driven local bandwidth selector based on a Wild Bootstrap approximation of the mean squared error of the estimators. The performance of the estimators and the local bootstrap bandwidth selection method are explored through simulation experiments.     

Multivariate numerical differentiation

We present an innovative method for multivariate numerical differentiation i.e. the estimation of partial derivatives of multidimensional noisy signals. Starting from a local model of the signal consisting of a truncated Taylor expansion, we express, through adequate differential algebraic manipulations, the desired partial derivative as a function of iterated integrals of the noisy signal. Iterated integrals provide noise filtering. The presented method leads to a family of estimators for each partial derivative of any order. We present a detailed study of some structural properties given in terms of recurrence relations between elements of a same family. These properties are next used to study the performance of the estimators. We show that some differential algebraic manipulations corresponding to a particular family of estimators lead implicitly to an orthogonal projection of the desired derivative in a Jacobi polynomial basis functions, yielding an interpretation in terms of the popular least squares. This interpretation allows one to (1) explain the presence of a spatial delay inherent to the estimators and (2) derive an explicit formula for the delay. We also show how one can devise, by a proper combination of different elementary estimators of a given order derivative, an estimator giving a delay of any prescribed value. The simulation results show that delay-free estimators are sensitive to noise. Robustness with respect to noise can be highly increased by utilizing voluntary-delayed estimators. A numerical implementation scheme is given in the form of finite impulse response digital filters. The effectiveness of our derivative estimators is attested by several numerical simulations.     

L─统计量的Bootstrap逼近

Ｌ─统计量的Ｂｏｏｔｓｔｒａｐ逼近任哲，陈明华（六安师范专科学校，六安２３７０１２）本文提出了Ｌ──统计量的一种Ｂｏｏｔｓｔｒａｐ逼近，并讨论了这种逼近的相合性及其逼近的精确性。一、引言及主要定理设兄，ｉ＞１为来自分布为Ｆ的ｉ．ｉ．ｄ．样本，以Ｘ．；...     

Multivariate numerical differentiation

We present an innovative method for multivariate numerical differentiation i.e. the estimation of partial derivatives of multidimensional noisy signals. Starting from a local model of the signal consisting of a truncated Taylor expansion, we express, through adequate differential algebraic manipulations, the desired partial derivative as a function of iterated integrals of the noisy signal. Iterated integrals provide noise filtering. The presented method leads to a family of estimators for each partial derivative of any order. We present a detailed study of some structural properties given in terms of recurrence relations between elements of a same family. These properties are next used to study the performance of the estimators. We show that some differential algebraic manipulations corresponding to a particular family of estimators lead implicitly to an orthogonal projection of the desired derivative in a Jacobi polynomial basis functions, yielding an interpretation in terms of the popular least squares. This interpretation allows one to (1) explain the presence of a spatial delay inherent to the estimators and (2) derive an explicit formula for the delay. We also show how one can devise, by a proper combination of different elementary estimators of a given order derivative, an estimator giving a delay of any prescribed value. The simulation results show that delay-free estimators are sensitive to noise. Robustness with respect to noise can be highly increased by utilizing voluntary-delayed estimators. A numerical implementation scheme is given in the form of finite impulse response digital filters. The effectiveness of our derivative estimators is attested by several numerical simulations.     

An innovation approach to the smoothing problem from uncertain observations with correlated signal and noise

This paper treats the least mean‐squared error linear fixed‐point and fixed‐lag smoothing problems from uncertain observations, when the variables describing the uncertainty are independent, and the signal and observation white noise are correlated. Using an innovation approach, recursive algorithms are derived for both estimators without requiring the whole knowledge of the state‐space model generating the signal, but only covariance information of the signal and the observation noise, as well as the probability that the signal exists in the observed values. Copyright © 2005 John Wiley & Sons, Ltd.     

Approximation to the distribution of the least squares estimators in two dimensional cosine models by randomly weighted bootstrap

Recently, Kundu and Gupta （Metrika, 48：83 C 97, 1998） established the asymptotic normality of the least squares estimators in the two dimensional cosine model. In this paper, we give the approximation to the general least squares estimators by using random weights which is called the Bayesian bootstrap or the random weighting method by Rubin （Annals of Statistics, 9：130 C 134, 1981） and Zheng （Acta Math. Appl. Sinica （in Chinese）, 10（2）： 247 C 253, 1987）. A simulation study shows that this approximation works very well.     

Malliavin Greeks without Malliavin calculus

We derive and analyze Monte Carlo estimators of price sensitivities (“Greeks”) for contingent claims priced in a diffusion model. There have traditionally been two categories of methods for estimating sensitivities: methods that differentiate paths and methods that differentiate densities. A more recent line of work derives estimators through Malliavin calculus. The purpose of this article is to investigate connections between Malliavin estimators and the more traditional and elementary pathwise method and likelihood ratio method. Malliavin estimators have been derived directly for diffusion processes, but implementation typically requires simulation of a discrete-time approximation. This raises the question of whether one should discretize first and then differentiate, or differentiate first and then discretize. We show that in several important cases the first route leads to the same estimators as are found through Malliavin calculus, but using only elementary techniques. Time-averaging of multiple estimators emerges as a key feature in achieving convergence to the continuous-time limit.     

Design of recursive least-squares fixed-lag smoother using covariance information in linear continuous stochastic systems

This paper newly designs the recursive least-squares (RLS) fixed-lag smoother and filter using the covariance information in linear continuous-time stochastic systems. It is assumed that the signal is observed with additive white observation noise and the signal is uncorrelated with the observation noise. The estimators require the covariance information of the signal and the variance of the observation noise. The auto-covariance function of the signal is expressed in the semi-degenerate kernel form.     

L1-Norm Estimation and Random Weighting Method in a Semiparametric Model

In this paper, the L_1-norm estimators and the random weighted statistic for a semiparametric regression model are constructed, the strong convergence rates of estimators are obtain under certain conditions, the strong efficiency of the random weighting method is shown. A simulation study is conducted to compare the L_1-norm estimator with the least square estimator in term of approximate accuracy, and simulation results are given for comparison between the random weighting method and normal approximation method.     

On estimation of time dependent spatial signal in Gaussian white noise

We consider an estimation problem for time dependent spatial signal observed in a presence of additive cylindrical Gaussian white noise of a small intensity ε. Under known a priori smoothness of the signal estimators with asymptotically the best in the mimimax sense risk convergence rate in ε to zero are proposed. Moreover, on-line estimators for the signal and its derivatives in t are also created.