资产专用性、企业价值与资本结构——基于信息技术上市公司面板数据的实证研究

本文通过选取2010年～2012年沪深两市信息技术行业上市公司的面板数据,研究资产专用性、企业价值与资本结构的关系。进行理论分析、面板数据单位根检验（ADF检验、LLC检验）、Hausman检验后,建立固定效应和Pooled EGLS的回归模型。结果表明：资产专用性在小于1％的显著性水平下与资本结构正相关,企业价值与资本结构负相关。此外,影响企业资本结构的因素还有：公司规模,成长性,盈利能力。     

论唐、五代昭义镇的地理环境和种族文化

昭义镇是唐代中原型藩镇之一,有其特殊的地理环境和种族文化,这种特殊性使昭义镇在唐中后期至五代初历史发展中起了重要作用。通过对昭义镇特殊地理环境和种族文化的论述和分析,可以揭示昭义镇在唐中后期至五代时在唐中央和地方藩镇关系中,在汴晋两大势力间有重要地位的原因,以及胡汉冲突的种族文化因素对昭义镇的发展和这段时期历史的影响。     

对英国铁路改革中一些问题的产权分析

本文试图用产权分析解释英国铁路民营化改革过程中出现的一些问题.分析认为改革初期设计的铁路管制体系使得路网公司Railtrack成为被强化管制的企业,其产权残缺严重是导致Railtrack日后因破产被政府接管的主要根源之一;彻底的"网运分离"大大增加了铁路产业内部的企业合作界面,带来了高昂的交易成本;将运输安全置于公共领域,没有专设安全监督机构,安全的"公地悲剧"是连续发生重大事故的主要原因之一;缺少对车辆等设备资产专用性的深入认识,结果使本应属于一体化的车辆部门被不合理分离.     

The diagnostic accuracy of a composite index increases as the number of partitions of the components increases and when specific weights are assigned to each component

The aim of this work was to evaluate whether the number of partitions of index components and the use of specific weights for each component influence the diagnostic accuracy of a composite index. Simulation studies were conducted in order to compare the sensitivity, specificity and area under the ROC curve (AUC) of indices constructed using equal number of components but different number of partitions for all components. Moreover, the odds ratio obtained from the univariate logistic regression model for each component was proposed as potential weight. The current simulation results showed that the sensitivity, specificity and AUC of an index increase as the number of partitions of components increases. However, the rate that the diagnostic accuracy increases is reduced as the number of partitions increases. In addition, it was found that the diagnostic accuracy of the weighted index developed using the proposed weights is higher compared with that of the corresponding un-weighted index. The use of large-scale index components and the use of effect size measures (i.e. odds ratios, ORs) of index components as potential weights are proposed in order to obtain indices with high diagnostic accuracy for a particular binary outcome.     

Occupational status benefits of studying abroad and the role of occupational specificity – A propensity score matching approach

Occupational status benefits of student mobility remain uncertain, despite increasing interest in the implications of international student mobility for the reproduction of societal inequality. Since mobile young people are a selective group in terms of socio-economic and achievement-oriented factors, we apply propensity score techniques to test whether German higher education graduates who did or did not study abroad differ in occupational status (based on the Socio-Economic Index of Occupational Status) three years after graduation. Analyses are based on multi-cohort representative data of the German population (Working and Learning in a Changing World). Results confirm a positively biased effect of mobility on early career occupational status driven by compositional differences. Subgroup analyses show that even when accounting for this bias, occupational status returns to mobility are positive for those graduating in occupationally unspecific fields of study. There are no returns for those graduating in occupationally specific fields of study. Findings also suggest that the effect of studying abroad is not homogeneous across the study population. Individuals less likely to study abroad are at the same time more likely to reap the occupational benefits from this experience.     

The influence of parents’ social capital on their children’s transition to vocational training in Germany

This study investigates the up-to-now strongly underexplored role of parents’ social capital in the school-to-work transition of adolescents. We base our empirical analyses on unique longitudinal largescale data from the German National Educational Panel Study. Parents’ social capital is measured with a position generator. Results show that adolescents with lower secondary education have better chances of finding an apprenticeship in a company if their parents know many persons with lower-status occupations for which vocational training is sufficient. This is especially the case for parents’ social contacts that have occupations in which many adolescents with lower secondary education are being trained in a company. The contrary is true for adolescents whose parents know many persons with higher-status occupations. Parents’ social networks do not show any effects on the quality of these apprenticeships or on the probability of entering school-based vocational training. Overall, our results indicate that parents’ social networks are important for a smooth school-to-work transition of their children. Moreover, our analyses confirm the idea that social capital is goal and labour market segment specific.     

Testing the equality of diagnostic effectiveness of one measure with respect to k different features

In several cases the same measurement is used as a marker for two or more population features, and it is useful to test whether this measurement has the same diagnostic effectiveness with respect to different features. In this paper we use the area under receiver operating characteristic curve as index for the discriminatory power among continuous variables and population features (eventuality, two or more diseases), and we propose a test to contrast the equality of the diagnostic effectiveness of this measurement.     

战略联盟的稳定性边界研究

战略联盟的高失败率决定了联盟稳定性研究的重要性.在一个专业化理论框架下,联盟的稳定性是由企业对于专业化水平和协作模式选择的动态决策过程所内生的,联盟的稳定性边界决定于投入联盟的资产专用属性、市场交易的效率和交易价格比以及战略联盟内部的交易效率.     

Between a ROC and a hard place: Teaching prevalence plots to understand real world biomarker performance in the clinic

The Receiver Operating Characteristic (ROC) curve and the Area Under the Curve (AUC) of the ROC curve are widely used in discovery to compare the performance of diagnostic and prognostic assays. The ROC curve has the advantage that it is independent of disease prevalence. However, in this note, we remind scientists and clinicians that the performance of an assay upon translation to the clinic is critically dependent upon that very same prevalence. Without an understanding of prevalence in the test population, even robust bioassays with excellent ROC characteristics may perform poorly in the clinic. While the exact prevalence in the target population is not always known, simple plots of candidate assay performance as a function of prevalence rate give a better understanding of the likely real‐world performance and a greater understanding of the likely impact of variation in that prevalence on translation to the clinic.