Bahadur efficiency of the F-test

Extremal problems in large deviations of the F-statistic are considered. It is shown that the slowest rate of convergence over a specified class of distributions of the F-statistic is slower than exponential, and that the Bahadur efficiency of the F-statistic with respect to some distribution-free competitors is identically zero.     

大文学白论

大文学是广义的文学,亦涵盖历史学、地理学、政治学、法学、哲学、经济学、社会学、军事学、体育学和宏观的自然科学等.大文学的特点是实硕、雅正,以修身齐家治国平天下为宗旨,以实用、教化为目的,而不仅仅局限于纯文学的审美鉴赏和文艺评析.大文学应当是文理百科的必修课程.     

Detecting Outliers in Large Medical Records: Using a Frontier Model

In this study, we want to detect the outliers from large medical records and exclude them because outliers will influence the accuracy and efficiency of the analysis. We compare the traditional method and the method from frontier model. In this study, we want to detect the outliers of cost and length of stay for pneumonia patients from HCUP 2002 and 2003.     

金融危机下大股东大宗交易行为的实证分析

通过对2006-2008年的138个大股东大宗增、减持公告数据进行实证分析,发现:大股东大宗交易行为能缓解金融危机下投资者羊群行为和过度反应,改善系统性和结构性市场定价效率;股权分置改革后,股权制衡度较高公司的控股股东倾向于增持,说明控制权竞争现象逐渐显现,这有益于外部治理机制改善;外部大股东没有起到被国外实证结果验证的惩罚低效管理的作用.应对大股东,尤其是外部大股东交易行为加强监管,保护中小股东利益.     

Graph based isomorph-free generation of two-level regular fractional factorial designs

We provide a new necessary and sufficient check for testing the isomorphism of two 2-level regular fractional factorial designs. The approach is based on modeling fractional factorial designs as bipartite graphs. We employ an efficient canonical graph labeling approach to compare two designs for isomorphism. We then improve upon the existing non-isomorphic fractional factorial design generation algorithm by reducing the number of candidate designs from which isomorphs need to be removed. Not only does our method generate non-isomorphic designs much faster, it is also able to generate designs with run sizes of 2048 and 4096 runs, which were not generated by the existing methods.     

基于熵值法的大中型工业企业R&D效率的区域差异测度与评价——以河南省为例

通过构建大中型工业企业R&D效率的评价指标体系,运用熵值法,对河南省18个地市大中型工业企业R&D效率区域差异进行了测度和分析。研究发现,河南大中型工业企业R&D效率区域不平衡性严重,自主创新支撑能力与环境约束是影响河南大中型工业企业R&D效率的关键因素。     

决策黑箱:现代投资决策理论新探

现代金融学关于经济主体投资决策的依据问题存在两种截然不同的观点,传统金融学基于理性预期认为投资主体决策的依据是信息;而行为金融学则从非理性出发认为主体决策不仅依据信息同时还由心理和情感因素决定。由于金融市场中投资主体理性选择与非理性选择的同时存在,在承认理性选择行为的同时,暗含着对非理性选择行为的默认,认为投资决策是一个存在"决策黑箱"的心理过程,投资主体依据理性还是非理性主要由主体情绪和信息获得与处理的复杂程度决定,对于相同的信息投资者根据当时的市场环境得出不同的判断,导致证券价格也会有不同的表现,决定集群行为的大数定律最终会发挥作用。     

大股东代理问题与IPO募集资金的使用

本文在单一股东价值模型的基础上,引入第一大股东的代理行为,并对IPO募集资金使用情况的影响因素进行理论分析,进而提出研究假说。用中国股市A股IPO数据对假说进行检验,发现IPO募集资金的使用受到第一大股东代理行为的影响,第一大股东政治级别越高和财务杠杆越小的上市公司的募集资金投入程度显著越低。IPO募集资金的使用也受到股东价值驱动因素的影响,上市后三年平均营业利润率越高的公司,IPO募集资金投入程度显著越高。     

中国上市公司大股东对投资影响的实证研究

本文以2001-2003年非金融性A股公司为样本,实证研究了大股东对公司投资的影响,并检验了这种影响的原因和作用过程。研究结果发现:(1)上市公司的投资与现金流显著正相关;(2)第一大股东持股比例与投资-现金流敏感度之间呈显著的负相关关系;(3)当第一大股东是国家时,负相关系数更大,当第一大股东是境内社会法人时,负相关关系不显著; (4)实证表明“过度投资”是中国上市公司投资的典型表现,这不仅符合“自由现金流假说”的推断,而且可以用“信息不对称理论”中“融资约束”相反的“融资便利”来加以解释。     

Dealing with the biased effects issue when handling huge datasets: the case of INVALSI data

The increasing prevalence of huge datasets addresses the research to appropriate statistical methods for solving troubles caused by their complexity. On the one hand, several techniques are mentioned in the literature, especially for the time-consuming and variables reduction issues. On the other, less debate is devoted to the statistical inference issue. Indeed, a large number of involved statistical units may lead to wrongly consider as significant variables without any actual impact on the phenomenon under study. This paper suggests a suitable subsampling procedure for the reduction of the number of statistical units and provides a novel index for the assessment of the significance effects. The proposal is validated by comparing results obtained from the analysis on the original data to those obtained from the proposed subsampling approach. The illustrative application focuses on the educational dataset made available by the National Committee for the Evaluation of the Italian Education Systems (INVALSI). This dataset collects information about the student features and achievements in Maths within the lower secondary schools of the Lombardy region (Italy). Due to the hierarchical structure of the data, a multilevel model is implemented with the purpose of investigating the effects of both individual and school factors on student Maths score.