位置参数的同时估计

在平方损失下，考虑ｐ（ｐ≥３）个位置参数的同时估计．对均匀分布、双指数分布给出了控制通常估计量的改进估计量，推广了Ｓｈｉｎｏｚａｋｉ（１９８４）的主要结果．     

复生长曲线模型中的球性检验问题

给出复情形下生长曲线模型球性检验似然比统计量与原假设相近的两类备择假设下的非零渐近分布．     

建立与完善有效管理行为的评价机制

随着现代企业制度的建立,对企业经营管理者经营管理业绩的考核与评价从过去重视产值和产量转变到重视质量和经济效益上来。随着企业委托代理关系的确立,对于代理人的经营管理行为应该加以监督、约束和激励。如何评价代理人的经营管理行为是问题的关键。对此,必须建立有效的管理行为评价机制,才能确保出资人的权益最大化。     

平面曲线的切线

平面解析几何对“求过二次曲线外的点所引曲线切线的方程”的问题,未给出一般的方法和公式。本文借助简单的微分运算对这一问题给出一种解决办法,并对一般的平面曲线的切线作了初步讨论。     

Statistical inference for Cox proportional hazards models with a diverging number of covariates

For statistical inference on regression models with a diverging number of covariates, the existing literature typically makes sparsity assumptions on the inverse of the Fisher information matrix. Such assumptions, however, are often violated under Cox proportion hazards models, leading to biased estimates with under-coverage confidence intervals. We propose a modified debiased lasso method, which solves a series of quadratic programming problems to approximate the inverse information matrix without posing sparse matrix assumptions. We establish asymptotic results for the estimated regression coefficients when the dimension of covariates diverges with the sample size. As demonstrated by extensive simulations, our proposed method provides consistent estimates and confidence intervals with nominal coverage probabilities. The utility of the method is further demonstrated by assessing the effects of genetic markers on patients' overall survival with the Boston Lung Cancer Survival Cohort, a large-scale epidemiology study investigating mechanisms underlying the lung cancer.     

On matric variate-T distribution

In this paper matric variate-t distribution has been studied. A factorization of the density is obtained in terms of the product of independent multivariate t- and F-densities. Further, the distributions of TAT1 and ATB, for given non-singular matrices A and B, are derived.     

Comparison of some common ratio estimators using pitman measure of nearness

In this article we compare some common ratio estimators for estimating the population total of a given characteristic. The sampling schemes considered are simple random sampling (S.R.S.) and S.R.S.under stratification. The comparisons are made using the Pitman Nearness criterion under the model-based approach. The error term is assumed normal with mean zero and variance σg(x). The function g(x) is a known function of the auxiliary variable x. Special interest is on the cases of g(x) =l and x. The result is found the same as that using MSE criterion, although the PN is very different from the MSE intrinsically.     

Harmonic mean approach to unbalanced mixed effects models under heteroscedastic variances

In this paper we consider unbalanced mixed models (Scheffe's model) under heteroscedastic variances. By using the harmonic mean approach, It is shown that the problems appear to be anologous to those problems from balanced mixed models under homoscedastic variance. Thus, by using harmonic mean approach, statistical inferences about fixed effects and variance components are derived by using those from balanced models under homoscedastic variance. Laguerre polynomial expansion is used Lo approximate sampling distributions of relevant statistics.     

Harmonic mean approach to uunbalanced random effects models under heteroscedasticity

In this paper we consider unbalanced random effects models under heteroscedastic variances. By using' the harmonic mean approach, it is shown that the problems are analogous to those from balanced random effects models under horaoscedastic variances. Thus, by using the harmonic mean approach, statistical inferences about variance components are derived by using procedures from balanced models under homoscedastic variances. Laguerre polynomial expansion is used to approximate the sampling distributions of relevant statistics.     

An approximation to the distribution of the ratio of two general quadratic forms with application

Based on mixed cumulants up to order six, this paper provides a four moment approximation to the distribution of a ratio of two general quadratic forms in normal variables. The approximation is applied to calculate the percentile points of modified F-test statistics for testing treatment effects when standard F-ratio test is misleading because of dependence among observations. For the special case, when data is generated by an AR(1) process, the approximation is evaluated by a simulation study. For the general SARMA (p,q)(P,Q)_s process, a modified F-test statistic Is given, and its distribution for the (0,1)(0,l)₁₂ process, is approximated by the moment approximation technique.