Bootstrap tests: how many bootstraps?

In practice, bootstrap tests must use a finite number of bootstrap samples. This means that the outcome of the test will depend on the sequence of random numbers used to generate the bootstrap samples, and it necessarily results in some loss of power. We examine the extent of this power loss and propose a simple pretest procedure for choosing the number of bootstrap samples so as to minimize experimental randomness. Simulation experiments suggest that this procedure will work very well in practice.     

Confidence intervals for secondary parameters following a sequential test

In sequential studies, formal interim analyses are usually restricted to a consideration of a single null hypothesis concerning a single parameter of interest. Valid frequentist methods of hypothesis testing and of point and interval estimation for the primary parameter have already been devised for use at the end of such a study. However, the completed data set may warrant a more detailed analysis, involving the estimation of parameters corresponding to effects that were not used to determine when to stop, and yet correlated with those that were. This paper describes methods for setting confidence intervals for secondary parameters in a way which provides the correct coverage probability in repeated frequentist realizations of the sequential design used. The method assumes that information accumulates on the primary and secondary parameters at proportional rates. This requirement will be valid in many potential applications, but only in limited situations in survival analysis.     

Nonparametric Tests for Stratum Effects in the Cox Model

Thispaper considers the stratified proportional hazards model witha focus on the assessment of stratum effects. The assessmentof such effects is often of interest, for example, in clinicaltrials. In this case, two relevant tests are the test of stratuminteraction with covariates and the test of stratum interactionwith baseline hazard functions. For the test of stratum interactionwith covariates, one can use the partial likelihood method (Kalbfleischand Prentice, 1980; Lin, 1994). For the test of stratum interactionwith baseline hazard functions, however, there seems to be noformal test available. We consider this problem and propose aclass of nonparametric tests. The asymptotic distributions ofthe tests are derived using the martingale theory. The proposedtests can also be used for survival comparisons which need tobe adjusted for covariate effects. The method is illustratedwith data from a lung cancer clinical trial.     

佣金制度的调整对我国证券市场的影响分析

对我国佣金制度改革的效果以及对证券市场的影响进行了实证研究 ,检验结果却出人预料 ,证券市场的交易量和平均价格都有明显的下降 ,难道这一救市政策失败了吗 ?文章通过分析 ,提出这一政策对我国的证券市场是有重大意义的     

中国股票市场有效性实证研究综述

对我国股票市场有效性的实证检验,不同的检验方法、样本区间和数据处理方法,都可能会影响得出不同的检验结论。本文从主要的实证检验、股票市场缺乏效率的原因、研究方法的创新与争论几个方面,对我国股票市场有效性的实证研究进行了综述,并对进一步研究的方向提出了建议。     

多元线性回归分析及其实际应用

本文主要介绍了多元线性回归分析的数学模型.同时结合实例演示了应用R软件实现多元线性回归的过程.     

进位保留阵列乘法器的一种内建自测试

对进位保留阵列乘法器提出了一种内建自测试方案。设计实现了采用累加器生成测试序列和压缩响应,并提出了一种改进的测试向量生成方法。分析与实验结果表明,该方案能实现非冗余固定型故障的完全覆盖。由于乘法器在数据通路中常伴有累加器,该方案通过对已有累加器的复用,作为测试序列生成和响应压缩,减少了硬件占用和系统性能占用,同时具有测试向量少、故障覆盖率高的特点。     

强化大学考务管理中学院的组织职能

综合性大学学生人数多、管理层次复杂,如何抓好考试组织工作是教学管理和考务管理面临的重要现实问题。在综合性大学中由于学生管理和教师管理的重心在学院,因此,考务管理、考试的组织管理重心也必然应该在学院。学院要以强化校风、学风、和教风建设为动力,以规范学院组织管理行为为重点,不断推动考风的好转。     

G函数与新古典—两部门分析

新古典主义模型和两部门分析是当代农业经济学的基本出发点,为发现对象空间里点上的规律做出了重要的贡献,已经成为理论发展的基本范式。G函数完成了一次对一般经济理论的大综合,推进了经济学理论核心的进展,引导出了新的探索方向。作为基本经济学原理的接受者和具体应用方向的开发者,农业经济学对此必定有积极的反应。将范式融入原理,大力开展试验和实验,将成为农业经济学理论取得新进展的主要方向。     

理学统治地位的确立与元中期学风的转变

元代中叶科举考试的恢复,奠定了程朱理学的统治地位,从而引起了元代中期学术风气的变 化,这种变化主要有三个特点,即趋于正、趋于实、趋于古。这种学风,对元中期雅正文学 思潮的形成产生重大影响。