交易者市场到达率及影响因素研究

将交易者市场到达率看作与市场状态相依的变量,实证研究了上海证券市场知情与非知情交易者的市场到达率及其影响因素.首先运用EKOP模型假设,选取2003.7.1至2003.12.31上海证券市场高频分笔交易数据,对知情与非知情者的到达率(交易强度)进行了度量;其次研究了各种宏观、微观市场特征对交易者到达率的影响.实证结果表明:非知情交易者的到达率与市场收益正相关,知情交易者的到达率主要受买(卖)交易量和供给(需求)弹性的影响,且这种影响只存在于同期之间.与非知情交易者不同,知情者较多的观察微观公共信息.     

流动性特征对知情、非知情交易的影响研究

利用生存分析理论建立一个高频交易强度模型,分析随市场流动性特征的改变,知情与非知情交易强度的变化． 选取上证流动性高和低两组股票数据作为对照样本,检验知情、非知情交易在不同流动性股票中的表现． 结果发现: 两组股票中,随着交易量的增加知情交易强度增大,非知情交易强度减少; 高流动股票中,随价差增大知情交易强度增加,非知情交易强度减少; 低流动股票中,随价差增大知情交易强度减少,非知情交易强度增加． 同时发现,两组股票, 知情交易间正相关; 高流动股中,知情交易与非知情交易间负相关; 而低流动股票中,知情交易与非知情交易间正相关．     

询价制度改革、知情交易者概率与IPO溢价

O'Hara理性预期模型假设非知情交易者对市场交易价格信息存在完全学习行为,从而知情交易者概率对资产期望收益产生负向效应。本文放松这一假设,引入非知情交易者学习程度,在理性预期模型框架下,以新股发行市场为背景对理性预期模型进行了拓展,模型结论表明：非知情交易者对市场交易价格的学习行为影响了知情交易者概率与资产期望收益的关系;当市场非知情交易者存在学习行为时,随着非知情交易者的学习程度加深,知情交易者概率对资产期望收益产生负向影响。在进一步的实证研究中,通过羊群效应验证了市场上非知情交易者的学习行为,以2010年1月到2011年12月在中小板上市的278家IPO公司为样本,对模型进行实证检验,实证结果支持理论模型结论。本研究对已有实证研究中知情交易者概率对资产收益产生正或负效应这一矛盾的研究结论提出了一种理论解释,并基于此对询价制度改革的有效性进行了检验。本文研究结论对知情交易者概率在资产定价中的适用性具有一定启示性,同时对非知情交易者的学习行为提出了一种实证检验的方法,具有一定的开创性。     

最优交易策略对交易持续期的影响

构建一个纯流动市场交易动态策略模型。假设交易者按Poisson过程到达市场,交易者根据其私人估值及市场状态对限价指令的收益做预期,通过最大化其收益确定所提交指令的类型(限价指令或市价指令)。模型发现,虽然交易者到达市场的时间间隔相互独立,但交易持续期却受前一期的交易策略影响:买(卖)指令的提交将增加下一期卖(买)交易持续期的期望值,减小下一期买(卖)交易的持续期的期望值。因而,交易间的自相关性是依据最优交易策略所内生的性质,与知情交易无关。     

指令驱动市场中非知情交易者的最优交易策略

在非对称信息下,综合非知情交易者对资产价值的预期、私人估值及资产价值波动,构造指令驱动市场价格形成的动态模型,给出非知情交易者指令提交策略的解析解,并依此描述了非知情交易者对资产价值预期的动态更新过程.研究发现:私人估值和资产价值波动通过影响非知情交易者最优策略,使得市场进入不同均衡状态;在每个均衡状态下,非知情交易者根据资产价值的预期变化更新交易策略,进而引起知情交易者策略调整,特别地,使得知情交易者被挤出市场成为可能.进一步分析表明,私人估值、资产价值波动及知情交易者比例对市场流动性的影响依赖于每个均衡中限价指令执行风险的差异.     

基于股评的投资者情绪对股票市场的影响北大核心CSCDCSSCI

探讨投资者情绪对我国股票市场的影响.为刻画投资者情绪,基于东方财富网股吧帖文与朴素贝叶斯方法,提出融合股评看涨看跌预期和投资者关注程度的投资者情绪度量指标.进一步,利用Granger因果检验、瞬时Granger因果检验、跨期回归分析等方法,探讨了投资者情绪对我国股票收益率、交易量和波动性是否具有预测能力及影响.实证结果揭示:虽然投资者情绪对股票市场收益率、交易量和波动性均无预测能力,但投资者情绪对股票收益率和交易量有当期影响;开盘前非交易时段的股评情绪对开盘价具有预测力,开盘后交易时段的股评情绪对收盘价和日交易量具有更显著的影响.此外,股票收益率是投资者情绪的Granger原因,即投资者情绪的形成依赖于前期市场收益率.这些实证结果为深入理解参与股吧评论的交易者的行为以及行为对市场产生的影响提供了证据.     

基于股评的投资者情绪对股票市场的影响

探讨投资者情绪对我国股票市场的影响.为刻画投资者情绪,基于东方财富网股吧帖文与朴素贝叶斯方法,提出融合股评看涨看跌预期和投资者关注程度的投资者情绪度量指标.进一步,利用Granger因果检验、瞬时Granger因果检验、跨期回归分析等方法,探讨了投资者情绪对我国股票收益率、交易量和波动性是否具有预测能力及影响.实证结果揭示:虽然投资者情绪对股票市场收益率、交易量和波动性均无预测能力,但投资者情绪对股票收益率和交易量有当期影响;开盘前非交易时段的股评情绪对开盘价具有预测力,开盘后交易时段的股评情绪对收盘价和日交易量具有更显著的影响.此外,股票收益率是投资者情绪的Granger原因,即投资者情绪的形成依赖于前期市场收益率.这些实证结果为深入理解参与股吧评论的交易者的行为以及行为对市场产生的影响提供了证据.     

机事不密: 股灾年降息降准前的知情交易

以2014年底至2015年底8次降息降准事件为自然实验,研究股市震荡中的知情交易和市场反应.研究结果表明,降息降准公布前,开盘价收益率、每笔成交量和知情交易比例显著提高,波动率和成交笔数显著下降;信息不对称程度高以及降息降准直接利好的银行、证券、房地产等行业的股票,其知情交易比例显著提高.进一步检验发现,降息降准公布前,每笔大单的规模和总大单数量显著提高,大单与小单的知情交易比例都显著高于正常日,且小单的知情交易比例在最后交易时段逐渐与大单接近.这些结果意味着股灾年中降息降准货币政策公布前知情交易在市场中是普遍存在的.隐含的信息传播途径是,资金雄厚的知情投资者首先买卖相关股票获得收益,并且知情交易在统计意义下先向其他资金雄厚的投资者扩散,随后是向中小散户扩散.     

公司传闻、澄清公告与知情交易——来自我国卖空交易的证据

文章以2010年4月至2018年3月中国A股融券标的公司为样本,从公司传闻与澄清公告的视角出发,对卖空与知情交易问题进行了考察.结果显示:首先,股票收益率在公司传闻发布前存在异动,说明传闻信息在正式发布前就已泄露,股票市场中存在知情交易者.其次,公司传闻发布前的异常卖空量与发布后的股票收益率显著负相关,说明卖空者能够预知公司传闻的发布时间和内容,是知情交易者.第三,良好的澄清公告效果能够削弱传闻发布前异常卖空对于传闻信息的反应,说明卖空者能够在一定程度上预判澄清效果,进一步支持了“卖空者是知情交易者”的推断.进一步研究表明,卖空者能够分辨传闻真伪,且私有信息挖掘是其重要的信息来源.本文从中国融券卖空实践出发,为“卖空者是否为知情交易者”这一争论提供了新的经验证据,同时对卖空机制与信息披露机制完善、公司传闻治理以及新闻媒体监管具有重要的现实意义.     

知情交易、信息不确定性与股票风险溢价

基于VPIN指标度量沪深300成分股的知情交易程度,并检验其定价效应及其与信息不确定性的交互作用.实证结果表明:1) VPIN可以通过提高买卖价差影响市场的流动性风险,并带来显著的横截面和时序上的风险溢价; 2) VPIN对风险溢价的解释能力优于信息不确定性因子,而信息不确定性对知情交易具有同向调节作用; 3)当对个股的信息不确定性、规模、动量以及变量之间的交互作用进行控制后,VPIN的定价效果依然显著存在.与此同时,Fama-Macbeth分析结果还表明,VPIN与传统风险因子不存在内生性问题,也不是传统风险因子的替代变量; 4)在公司发布各类重大公告前都存在显著的异常风险溢价和异常交易量,而上述异常值可以被同步出现的异常VPIN值所解释.     

Educational Landscapes and Urban Development. Contextual and Spatial Interfaces and Linkages

In the broad sociopolitical discussion on education quality within the last decade, it has become apparent that education is gaining importance for urban development, as well as space and the urban context are important dimensions of education. This becomes particularly evident in concepts for local educational landscapes (Ger. Bildungslandschaften). The young field of research on educational landscapes is currently lacking empirical research from spatial and planning sciences. In the paper, the current state of scientific research on educational landscapes in Germany and Europe and first insights to contextual and spatial interfaces and linkages between education and urban development in general are presented.     

Inventory Models with Continuous and Poisson Demands and Discounted and Average Costs

We develop a new, unified approach to treating continuous‐time stochastic inventory problems with both the average and discounted cost criteria. The approach involves the development of an adjusted discounted cycle cost formula, which has an appealing intuitive interpretation. We show for the first time that an (s, S) policy is optimal in the case of demand having a compound Poisson component as well as a constant rate component. Our demand structure simultaneously generalizes the classical EOQ model and the inventory models with Poisson demand, and we indicate the reasons why this task has been a difficult one. We do not require the surplus cost function to be convex or quasi‐convex as has been assumed in the literature. Finally, we show that the optimal s is unique, but we do not know if optimal S is unique.     

E-governance and Corruption-developments and Issues in Ethiopia

This paper reports the results of a survey of 400 respondents in Ethiopia about factors generating corruption and the potential of e-Governance to mitigate corruption. It is suggested that e-Governance can help not only in weeding out corruption but also in the establishment of sounder government citizen relationships in Ethiopia. While e-Governance cannot cure all the structural factors that breed corruption in the society, strategic implementation of e-Governance can help improve the critical variable in combating corruption-government citizen relationships. It is argued that while e-Governance initiatives can make important contributions to improving public services they can best do so by helping improve overall relationships between governments and citizens.

CEO and Chairperson characteristics and firm performance

This paper focuses on the relationship between Chief Executive Officer (CEO) and Chairperson characteristics and firm performance. Specifically, the study examines the association between the characteristics of the CEO and the Chairperson of the board and firm performance. Using a sample of S&P 500 firms, the evidence found suggests that demographic and experience-related characteristics may be associated with the market valuation and financial performance of the firm. In particular, the reported results indicate a positive relationship between the presence of female CEOs or Chairs and firm performance, thus suggesting that gender-based differences may affect the CEO’s/Chairperson’s success. Moreover, the findings concerning the age of the CEO or Chair are mixed, while their experience and quality appear positively related to firm performance. Interestingly, a CEO or Chairperson holding multiple board seats is negatively associated with firm performance, whereas CEO duality has a positive relationship with Tobin’s Q and the return on assets (ROA) of the firm.     

David and Goliath: causes and effects of coopetition between start-ups and corporates

Coopetition (collaboration between competitors) among young firms (i.e. start-ups) and larger, more established firms (i.e. corporates) may be beneficial for both partners as each party typically has something to offer that is missing in the other. Start-ups often develop innovative ideas, are flexible and agile, willing to take risks, and aspire to achieve high growth, but they tend to lack the required resources, capabilities, and knowledge due to their newness and smallness. Corporates have resources, routines, and experience that enable them to work efficiently but lack a certain innovation capability. Research has suggested that coopetition represents an opportunity for start-ups facing restrictions in resources, while corporates benefit from start-ups’ innovative ideas. However, it is yet unknown whether start-ups and corporates engage in coopetition with each other and, if so, how and why they do this. This study seeks to fill this void by exploring the motives of coopeting start-ups and corporates, how they manage their coopetitive relationship, and what implications occur including potential benefits and risks. We present a multiple case study based on qualitative data collected through 70 interviews with Austrian-based start-ups and corporates representing 35 coopetitive partnerships. Discussing the findings based on our data, we propose relationships concerning coopetition and its role to enlarge resource- and technology-bases as well as its role in the development of dynamic capabilities.     

Career orientations and career success among research,and development and engineering professionals

Managing the careers of research, development and engineering (RD&E) professionals is important to the strategic use of RD&E in the economy. Appropriate mechanisms for motivating RD&E professionals will probably emerge as a critical success factor for organizations that want to compete in world markets. This study examines dimensions and levels of career orientation and their correlations with individual and work-related outcome variables among 78 RD&E professionals. The findings reveal a rich diversity of career orientation in RD&E professionals. The data strongly suggest that RD&E professionals are service, lifestyle and security oriented. However, they scored low on technical orientation and entrepreneurship. This paper suggests that the dual career ladder is not an effective device for managing RD&E professionals. Organizations must be careful to provide career paths that retain and motivate workers and, more importantly, find matches between organizational needs and individuals' needs, and restructure jobs accordingly. The authors offer suggestions for future research and identify implications for management.     

Modeling Pathology Workload and Complexity to Manage Risks and Improve Patient Quality and Safety

Anatomic pathology (AP) laboratories provide critical diagnostic information that help determine patient treatments and outcomes, but the risks of AP operations and their impact on patient safety and quality of care remain poorly recognized and undermanaged. Hospital-based laboratories face an operational and risk management challenge because clinical work of unknown quantity and complexity arrives with little advance notice, which results in fluctuations in workload that can push operations beyond planned capacity, leading to diagnostic delays and potential errors. Modeling the dynamics of workload and complexity in AP offers the opportunity to better use available information to manage risks. We developed a stock-and-flow model of a typical AP laboratory operation and identified key exogenous inputs that drive AP work. To test the model, we generated training and validations data sets by combining data from the electronic medical records and laboratory information systems over multiple years. We demonstrate the implementation of 10-day AP work forecast generated on a daily basis, and show its performance in comparison with actual work. Although the model somewhat underpredicts work as currently implemented, it provides a framework for prospective management of resources to ensure quality during workload surges. Although full implementation requires additional model development, we show that AP workload largely depends on few and accessible clinical inputs. Recognizing that level loading of work in a hospital is not practical, predictive modeling of work can empower laboratories to triage, schedule, or mobilize resources more effectively and better manage risks that reduce the quality or timeliness of diagnostic information.     

Work and shopping overflow — Consequences and differentiation among selected psychological and demographic characteristics

Contemporary individuals are forced to deal with excessive stimulation, which causes an overload in the cognitive and emotional areas. The purpose of this paper is to investigate the possible factors differentiating the perceived level of work and shopping overflow experienced by individuals and consequences of these states. Two psychological variables: cognitive control and sensation seeking, are chosen as potential factors differentiating the perceived levels of overflow. We assume that individuals with high cognitive control and sensation seeking will report lower levels of both types of examined overflows. Experiencing low overflow levels may manifest in the search for additional stimuli, rather than in the desire to limit them. Two indexes of behavior connected to seeking extra stimulation are selected: one belonging to the area of consumer behavior (readiness to participate in the experience economy) and one belonging to vocational behavior (choosing a boundaryless career). The quantitative study is conducted on a sample of 297 management students who are currently employed. The research results support the relation between cognitive control and perceived level of work and shopping overflow. Individuals who can cognitively control the situation and the incoming stimuli report lower levels of overflow. No significant relationship between sensation seeking and the level of overflow is found. The demographic variables that influence the perceived overflow are age and salary for work overflow and age for shopping overflow. As far as consequences of overflow are concerned, a low level of shopping overflow is related to readiness to participate in the experience economy. However, there is no link between work overflow and preferred career pattern. The managerial implications for human resource management and marketing strategy design are discussed.     

Review and reappraisal of modelling and predicting mental workload in single- and multi-task environments

The concept of mental workload has long been recognized as an important factor in individual performance within complex systems. It is documented that either overload or underload may degrade performance, and further affect the efficiency of the whole system. Therefore, systems designers need some explicit models to predict the mental workload imposed on individuals by the system at an early design phase so that alternative system designs can be evaluated. In examining mental-workload literature, it is found that few predictive mental-workload models have considered factors specific to individuals. This research aims to develop a practical framework for predicting mental workload in both single- and multi-task environments considering such individual factors. In order to describe mental workload more precisely and more completely, a framework for mentalworkload definitions, which contains instantaneous workload, average workload, accumulated workload, peak workload and overall workload, is proposed. In order to model individual factors, two new variables, i.e. effective workload and ineffective workload, are introduced to model the taskgenerated workload and individual-generated workload. The extension of the model to multi-task environments is also discussed. The proposed conceptual models are domain-independent and could be used to guide the development of operational models for different specific tasks.