中国股指期货对股票市场的流动性影响

随着中国股指期货的推出,股指期货对股票市场流动性的影响又成为一个新的课题。文章运用向量自回归(VAR)模型、Granger因果检验分析了中国股指期货对股票市场的流动性影响,检测了流动性溢价理论在中国股指期货市场的应用。最终得出结论,股票市场的买卖价差和期货现货基差之间存在双向的因果关系,即股票市场的流动性波动对投资股指期货的预期收益变化有重要的作用。     

项目制:一种新的国家治理体制(英文)

作为新双轨制的增量部分,项目制旨在通过国家财政的专项转移支付等项目手段,突破以单位制为代表的原有科层体制的束缚,遏制市场体制所造成的分化效应,加大民生工程和公共服务的有效投入。以项目制为核心确立的新的国家治理体制,形成了中央与地方政府之间的分级治理机制,并对基层社会产生了诸多意外后果。项目制所引起的基层集体债务、部门利益化以及体制的系统风险,对于可持续的社会发展将产生重要影响。     

扭带管内油的受迫对流换热实验

以30~#透平油为工质,对在光管内插入三种不同扭率扭带的受迫流动的冷、热态流阻及换热性能进行了实验。实验的雷诺数为200～1150,普朗特数为320～590,实验结果表明:在本实验范围内,插有不同扭率的全长连续扭带管的换热系数为光管的1.7～2.6倍,而阻力系数为光管的3～7.5倍;且扭率的大小对扭带的流阻与换热影响较大。另外,还对间断扭带管内油的受迫对流换热进行了实验。     

家族企业权力配置对会计稳健性影响的实证分析

以2005~2014年福建省家族企业作为研究对象,考察家族企业的权力配置对企业会计稳健性的影响。通过对310个样本企业的实证分析发现,与家族企业实际控制人不担任董事长和总经理任何一个职位的企业相比,家族企业实际控制人担任董事长、总经理之一或者同时担任董事长和总经理的企业,会计稳健性更差;家族控制力越强,会计稳健性越差。研究结果表现,家族介入企业运营管理削弱了企业会计信息质量。     

历史记忆与家族建构——以湘西田氏土司后裔为中心的考察

作为传递历史记忆的媒介,口述传说、文字、身体、仪式、碑刻等不一定能完全客观地呈现历史事实,但透过这些方式选择、重组与诠释的“过去”,往往成为人们合理化当前社会现实的重要方式。湘西古丈县田家洞为改土归流前永顺宣慰司下辖的小长官司,村中土司后裔——田氏自改革开放后,藉由祖先传说、修谱与立碑、仪式展演等活动叙写家族历史,强化族众认同。实际上,围绕历史记忆展开的家族建构不仅体现了不同能动者之间的权力角逐,也为诠释“传统”在现代社会的复苏提供了一种视角。     

基于Benders分解算法的跨区互联电力系统协调规划模型

研究跨区互联电力系统的协调规划,对于提高投资效率实现更大范围的资源配置具有较强现实意义。本文首先描述多区域电力系统扩张规划问题,并建立多区域扩张规划模型,旨在寻求最优的扩容方案,以最小投入来满足多区域电力系统负荷增长需求;其次,采用Benders分解算法将多区域扩张规划问题分解为一个规划主问题和一个运行子问题,通过主子问题之间的迭代求解,获得最终的最优解;最后,对某个典型的包含7个区域的多区域电力系统进行模拟仿真,验证了本文所构建模型及算法的有效性。     

Likelihood estimation for longitudinal zero-inflated power series regression models

In this paper, a zero-inflated power series regression model for longitudinal count data with excess zeros is presented. We demonstrate how to calculate the likelihood for such data when it is assumed that the increment in the cumulative total follows a discrete distribution with a location parameter that depends on a linear function of explanatory variables. Simulation studies indicate that this method can provide improvements in obtaining standard errors of the estimates. We also calculate the dispersion index for this model. The influence of a small perturbation of the dispersion index of the zero-inflated model on likelihood displacement is also studied. The zero-inflated negative binomial regression model is illustrated on data regarding joint damage in psoriatic arthritis.     

Estimating the prevalence of low-lumbar spine bone mineral density in older men with or at risk for HIV infection using normal mixture models

Bone mineral density decreases naturally as we age because existing bone tissue is reabsorbed by the body faster than new bone tissue is synthesized. When this occurs, bones lose calcium and other minerals. What is normal bone mineral density for men 50 years and older? Suitable diagnostic cutoff values for men are less well defined than for women. In this paper, we propose using normal mixture models to estimate the prevalence of low-lumbar spine bone mineral density in men 50 years and older with or at risk for human immunodeficiency virus infection when normal values of bone mineral density are not generally known. The Box–Cox power transformation is used to determine which transformation best suits normal mixture distributions. Parametric bootstrap tests are used to determine the number of mixture components and to determine whether the mixture components are homoscedastic or heteroscedastic.     

Local power properties of some asymptotic tests in symmetric linear regression models

In this paper we obtain asymptotic expansions, up to order n^−1/2 and under a sequence of Pitman alternatives, for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in the class of symmetric linear regression models. This is a wide class of models which encompasses the t model and several other symmetric distributions with longer-than normal tails. The asymptotic distributions of all four statistics are obtained for testing a subset of regression parameters. Furthermore, in order to compare the finite-sample performance of these tests in this class of models, Monte Carlo simulations are presented. An empirical application to a real data set is considered for illustrative purposes.     

Testing bioequivalence for multiple formulations with power and sample size calculations

Bioequivalence (BE) trials play an important role in drug development for demonstrating the BE between test and reference formulations. The key statistical analysis for BE trials is the use of two one‐sided tests (TOST), which is equivalent to showing that the 90% confidence interval of the relative bioavailability is within a given range. Power and sample size calculations for the comparison between one test formulation and the reference formulation has been intensively investigated, and tables and software are available for practical use. From a statistical and logistical perspective, it might be more efficient to test more than one formulation in a single trial. However, approaches for controlling the overall type I error may be required. We propose a method called multiplicity‐adjusted TOST (MATOST) combining multiple comparison adjustment approaches, such as Hochberg's or Dunnett's method, with TOST. Because power and sample size calculations become more complex and are difficult to solve analytically, efficient simulation‐based procedures for this purpose have been developed and implemented in an R package. Some numerical results for a range of scenarios are presented in the paper. We show that given the same overall type I error and power, a BE crossover trial designed to test multiple formulations simultaneously only requires a small increase in the total sample size compared with a simple 2 × 2 crossover design evaluating only one test formulation. Hence, we conclude that testing multiple formulations in a single study is generally an efficient approach. The R package MATOST is available at https://sites.google.com/site/matostbe/ . Copyright © 2012 John Wiley & Sons, Ltd.