特质风险、投资者偏好与股票收益——基于前景理论视角的分析

股票特质风险与预期回报之间的关系一直是学术界争论的焦点.本文在前景理论视角下探究特质波动率、投资者偏好行为及股票预期回报之间的关系,建立了理论模型分析特质波动率对投资者偏好的影响,结果表明:当股票有未实现的资本损失时,特质波动率越大的股票对投资者的吸引力越强,预期收益率与特质波动率负相关;而当股票有未实现的资本收益时,特质波动率越小的股票对投资者的吸引力越强,预期收益率与特质波动率正相关.文章使用Fama-French五因子模型计算特质波动率,使用前景理论效用值衡量投资者偏好,以中国股票市场的实际数据为基础,通过分组检验和Fama-MacBeth回归的方法证明了理论模型的结论.基于前景理论视角的分析在为股票特质风险方向的理论研究形成有益补充的同时,也为投资者的风险管理和资本市场的健康发展提供了理论依据与现实指导.     

“坏”跳跃、“好”跳跃与高频波动率预测

  准确的波动率预测对资产组合配置和风险管理有非常重要的意义，在当今大数据时代，充分利用股市高频数据预测股票波动率成为可能。         股市高频信息的一种应用是使用已实现方差和它的组成部分预测股票波动率。已实现方差可以拆分为已实现负半方差和已实现正半方差两个部分。由于已实现负半方差和已实现正半方差极限形式中包含的连续运动部分完全一致，所以它们的不同仅来源于它们跳跃部分的差异，但连续运动部分的存在是否会“稀释”股价跳跃对波动率所产生的影响，为此有必要进一步提取负跳跃和正跳跃。基于负跳跃变差和正跳跃变差，利用HAR模型研究两种不同方向的跳跃是否对波动率产生不对称影响，使用DM统计量和样本外 R²_OS，作为评判标准，考察这种区分跳跃方向的做法是否改进了对波动率的预测能力。         研究结果表明，①负跳跃对应未来波动率上升，正跳跃对应未来波动率下降。作为风险规避者的投资者厌恶风险和不确定性，意味着投资者厌恶未来波动率上升而偏好未来波动率下降。因此，将股价的负跳跃称为“坏”跳跃，将股价的正跳跃称为“好”跳跃。②“好”跳跃导致未来波动率下降，而连续运动部分的上升导致未来波动率上升，两者效应的总和是已实现正半方差对未来波动率的影响不显著；“坏”跳跃和连续运动部分的上升都导致未来波动率上升，两者效应的总和是已实现负半方差对未来波动率产生显著的正影响。③利用“坏”跳跃和“好”跳跃不但能够更好地拟合样本内的未来波动率，而且还能够明显地改善波动率的样本外预测能力。         研究结果支持日内收益率的正负符号信息在波动率预测领域有其价值，两种不同方向的跳跃对波动率产生不对称影响。在波动率预测实践中，利用“坏”跳跃和“好”跳跃能够改进对波动率的预测能力。     

尾风险度量与定价能力分析

经典资本资产定价模型假设资产收益服从正态分布或者投资者效用函数是二次型，然而实际中资产收益的分布呈现尖峰厚尾特征，因而无法在均值-方差框架下分析风险与收益的关系。与资产收益正常变化相比，极端变化带来的尾风险会对市场风险和投资者的决策行为产生更为显著的影响，因此研究尾风险的度量方法和定价能力具有一定理论和实践意义。 依据极值理论，基于Fama-French的3因子模型无法解释的收益残差构建尾风险度量模型。选取中国股票市场沪深A股作为研究对象，以历史滑动窗估计尾风险，投资组合分析和横截面回归分析的结果都表明尾风险可以稳定地负向预测股票收益，在控制规模、交易量、非流动性、短期反转、中期动量、特质波动率、特质偏度等股票特征后，尾风险的负向预测能力依然显著。引入融资融券交易，发现融资融券标的股票的尾风险显著低于非融资融券标的股票的尾风险，而且可以消除尾风险的负向溢价，因而中国资本市场尚未完全开放融资融券交易机制可能是产生尾风险负向溢价的主要原因。 通过买多-卖空组合构建尾风险定价因子，发现尾风险因子比投资因子和盈利因子有更高的风险价格，而且并不是相对于Fama-French的5因子的冗余因子。与Fama-French的3因子模型和5因子模型相比，Fama-French的3因子或5因子基础上包含尾风险因子的定价模型对股票横截面收益有更好的解释能力，因而有更高的定价效率。 2008年全球金融危机爆发后，对尾风险定价能力的忽略使已有资产定价模型受到广泛批评。因此，探究尾风险的度量方法以及分析尾风险的定价能力，不仅有助于完善和拓展资产定价理论，而且有助于降低投资者对股票价格的认知偏差，提升市场资源配置效率和维护市场稳定性。     

基于贝叶斯因子模型金融高频波动率预测研究

构建了包含时变系数和动态方差的贝叶斯HAR潜在因子模型(DMA(DMS)-FAHAR),并对我国金融期货(主要是股指期货和国债期货)的高频已实现波动率进行预测.通过构建贝叶斯动态潜在因子模型提取包含波动率变量、跳跃变量和考虑杠杆效应的符号跳跃变量等预测变量的重要信息.同时,在模型中加入了投机活动变量,以考察市场投机活动对中国金融期货市场波动率预测的影响.预测结果表明,时变贝叶斯潜在因子模型在所有参与比较的预测模型当中具有最优的短期、中期和长期预测效果.同时,具有时变参数和时变预测变量的贝叶斯HAR族模型在很大程度上提高了固定参数HAR族模型的预测能力.在股指期货和国债期货的预测模型中加入投机活动变量可以获得更好的预测效果.     

中国股票价格跳跃实证研究

利用基于BN -S方法的已实现波动测度构造出跳跃统计量,用该统计量检验分析了中国股票市场股票价格的跳跃现象.检验结果不仅证实了股票市场价格跳跃存在普遍性,而且发现单支股票的跳跃主要是异质跳跃而不是共同跳跃.这表明单支股票的价格跳跃更多地受到自身市场信息的影响,而共同信息对单支股票的影响是非常有限的.单支股票的共同跳跃大...     

跳跃的估计、股市波动率的预测以及预测精度评价

本文基于C_TMPV理论估计已实现波动率的跳跃成分,在此基础上构建考虑跳跃的AHAR-RV-CJ模型和MIDAS-RV-CJ模型来预测中国股市的已实现波动率,并评价和比较各类波动率模型的预测精度。实证结果表明:基于C_TMPV估计的波动率跳跃成分对日、周以及月波动率的预测有显著的正向影响;AHAR-RV-CJ模型和MIDAS-RV-CJ模型的样本内和样本外预测精度在不同的预测时域上都是最高的,尤其是对数形式的模型;MIDAS族模型的样本外预测精度在中长期预测时域上比HAR族模型高;AHAR-RV-CJ模型和MIDAS-RV-CJ模型的样本外预测能力在中长期预测时域上比基于低频数据的Jump-GARCH模型、SV-CJ模型和SV-IJ模型好。     

“特质波动率之谜”与估计模型有关吗？

以CAPM、Fama-French三因子和五因子模型为均值方程,分别采用无条件标准差,以及GARCH、EGARCH条件方差为基准计算出中国股票市场的特质波动率,研究了特质波动率与股票收益率之间的关系。研究发现,关于高特质波动风险对应低预期收益的定价异象来源于特质波动率估计模型的差异。具体地,当使用无条件标准差方式估计特质波动率时,存在定价异象,而使用GARCH、EGARCH等条件方差模型估计特质波动率时,则不存在定价异象。该结果在改变残差估计均值方程以及控制规模、流动性等其它变量后依然稳健。本文的研究有助于解释长期困扰在资产定价领域的“特质波动率之谜”。     

基于四次幂差修正HAR模型的股指期货波动率预测

股指期货波动率建模与预测是揭示其波动运行规律和市场风险是重要途径。本文基于跳跃、好坏波动率与符号跳跃建立四组HAR模型，提出单级纠偏HARQ类模型和多级纠偏HARQF类模型，实证研究揭示股指期货波动运行规律，并采用MCS检验来评估模型优劣。HAR建模考察连续与跳跃波动、好与坏波动率的两种已实现波动分解。为了降低波动率估计偏差，基于最小化MSE准则确定最优抽样频率，利用已实现核修正的ADS检测法识别跳跃，采用已实现核估计修正好坏波动率与符号跳跃。基于沪深300股指期货的实证研究表明：连续波动比跳跃波动对未来已实现波动贡献更大；好坏波动率具有不对称波动冲击，而符号跳跃对未来波动具有负向冲击；好坏波动率分解优于连续与跳跃波动分解；中位数已实现四次幂差能够显著提升HAR类模型的样本内外预测能力；与样本内预测相反，样本外预测中单级纠偏HARQ类模型优于多级纠偏HARQF类模型；MCS检验得出HARQ-RV-SJ模型表现最佳。研究结论与启示对认识股指期货波动规律和市场风险具有意义。     

股票收益的截面差异与三因素资产定价模型来自A股市场的经验研究

本文研究沪深A股市场股票收益率的截面性质,并检验Fama-French三因素资产定价模型在中国A股市场的适用性。结果表明,沪深A股市场存在着公司规模效应和股东权益帐面市值比效应,基于市场组合、公司规模和股东权益帐面市值比的Fama-French三因素模型基本上可以解释A股市场收益率的截面差异,但不能完全解释惯性与反转投资策略的超额收益。     

股票特质波动率、股票收益与投资者情绪

从理论和实证两个角度分析股票特质波动率、股票收益与投资者情绪之间的动态关系。将受投资者情绪影响的噪声投资者引入Merton基于不完全信息的市场均衡模型,以2007年至2012年沪、深两市A股上市公司数据为样本,运用有向无环图(DAG)技术识别SVAR模型,实证检验股票特质波动率与股票收益和投资者情绪的相关性。研究结果表明,股票特质波动率与股票收益正相关;股票收益率对股票特质波动率的弹性,随着投资者情绪的增加和噪声投资者比例的上升而增大。投资者情绪和股市流动性是影响中国股票市场高特质波动股票与低特质波动股票截面收益差异大小的重要原因。投资者越乐观、市场上流动性越强,高特质波动组合收益率与低特质波动组合收益率的截面差异就越大。研究结果有利于加深对投资者行为的认识,从更符合中国资本市场情况的角度分析股票特质波动率与股票收益的关系。     

Power,authority and legitimacy

Management, human resources, organization, control, leadership, etc., all seem to be just so many euphemisms for power, and this suggests a discourse of management and organization that calls things by their proper name. This paper on the contrary stresses the need to resolve the concept of ‘power’ itself into more differentiated notions, and proposes that clarification may be derived from distinctions once explicit in the vocabulary of Classical antiquity, but lost in modern European languages. It argues that nothing but confusion in thinking about organizations, management and legitimation can result from the failure to recognize that the phenomena this vocabulary identifies and distinguishes are irreducibly different.     

Criteria for selecting a production control philosophy

Logistic objectives constitute a compromise between having short leadtimes and a low volume of work in progress on the one hand and a high resource loading and due date obligation on the other. Miscellaneous production planning approaches offered today provide different combinations of logistic objectives for satisfying a manufacturing strategy. To combine the strength of the various approaches into a unified system, a new approach based on a dynamic and distributed production planning methodology is proposed. To customize the approach, various analyses and specifications have to be made and for that reason some important characteristics and criteria for analysing production control philosophies will be given.     

The social construction of the meaning of acute stressors: a qualitative study of the personal accounts of police officers using a stress counselling service

The police profession is one in which acute stressors are encountered more frequently than in other occupations. Using the personal accounts of 35 police officers attending an in-house stress counselling clinic, the aim of the present study was to provide a qualitative examination of how the institutional context of policing influenced the ways in which acute stressors signified to individual police officers experiencing felt distress. Using the framework of Rational Emotive Behaviour Therapy as an analytical tool, it is argued that beliefs contributing to the experience of felt distress are related to the way in which policing as both an identity and an activity is constructed through the police organizational culture. Not only do these constructions influence the ways in which officers perceive themselves and their environments, but they also operate at the collective level to 'normalize' some emotional responses and to 'pathologize' others which, it is argued, could impact upon the outcomes of interventions such as stress counselling.     

The moderating role of social support in Karasek's job strain model

This paper examines whether social support is a boundary-determining criterion in the job strain model of Karasek (1979). The particular focus is the extent to which different sources of social support, work overload and task control influence job satisfaction, depersonalization and supervisor assessments of work performance. Hypotheses are tested using prospective survey data from 80 clerical staff in a university setting. Results revealed 3-way interactions among levels of support (supervisor, co-worker, non-work), perceived task control and work overload on levels of work performance and employee adjustment (self-report). After controlling for levels of negative affect in all analyses, there was evidence that high levels of supervisor support mitigated against the negative effects of high strain jobs on levels of job satisfaction and reduced reported levels of depersonalization. Moreover, high levels of non-work support and co-worker support also mitigated against the negative effects of high strain jobs on levels of work performance. The results are discussed in terms of the importance of social support networks both at, and beyond, the work context.     

Job insecurity, coping resources and personality dispositions in occupational strain

This paper presents research on the relationships between the work-related stressor of perceived job insecurity and various indicators of occupational strain, taking into account employees' personality dispositions (trait negative and positive affectivity) and coping resources. Respondents were 222 Australian public servants surveyed during organizational restructuring that involved downsizing and threat to job certainty. The research was formulated within an adaptation of Osipow, Doty, and Spokane's (1985) framework of stress-strain-coping that included the possible direct as well as moderating effects of personality dispositions in reporting occupational strain (Parkes, 1990). Findings from hierarchical regression analyses indicate consistent significant independent effects of personality dispositions, coping resources and perceived job insecurity on various indicators of strain. There was also support for the moderating roles of negative affectivity and self-care in the relation between perceived job insecurity and physical strain. Implications for the role of dispositional factors, especially negative affectivity, and the utility of various coping resources in accounting for occupational strain in times of threatened job security are discussed.     

Job stress, job strain, and psychological withdrawal among Dutch university staff: towards a dualprocess model for the effects of occupational stress

This study examined the antecedents of job strain (emotional exhaustion, health complaints) and withdrawal behaviour (e.g. lowered organizational commitment) among a cross-sectional sample of 131 academic staff members of the law department of a large Dutch university. Conservation of resources theory (Hobfoll, 1989) provided the theoretical background for this study. Strains and withdrawal behaviours were expected to be most prominent among those who reported having few resources and/or who reported high job demands. Structural equation modelling revealed that this was indeed the case. As predicted, differential patterns of effects emerged for job demands and job resources. Analysis of the effects of four job-specific stressors revealed that especially the structural aspects of a staff member's teaching task (e.g. the number of students in their classes) contributed strongly to perceived job demands. Theoretical and practical implications of the study are discussed.     

Dermal Uptake of 18 Dilute Aqueous Chemicals: In Vivo Disappearance‐Method Measures Greatly Exceed In Vitro‐Based Predictions

Average rates of total dermal uptake (K_up) from short‐term (e.g., bathing) contact with dilute aqueous organic chemicals (DAOCs) are typically estimated from steady‐state in vitro diffusion‐cell measures of chemical permeability (K_p) through skin into receptor solution. Widely used (“PCR‐vitro”) methods estimate K_up by applying diffusion theory to increase K_p predictions made by a physico‐chemical regression (PCR) model that was fit to a large set of K_p measures. Here, K_up predictions for 18 DAOCs made by three PCR‐vitro models (EPA, NIOSH, and MH) were compared to previous in vivo measures obtained by methods unlikely to underestimate K_up. A new PCR model fit to all 18 measures is accurate to within approximately threefold (r = 0.91, p < 10^?5), but the PCR‐vitro predictions (r > 0.63) all tend to underestimate the K_up measures by mean factors (UF, and p value for testing UF = 1) of 10 (EPA, p < 10^?6), 11 (NIOSH, p < 10^?8), and 6.2 (MH, p = 0.018). For all three PCR‐vitro models, log(UF) correlates negatively with molecular weight (r² = 0.31 to 0.84, p = 0.017 to < 10^?6) but not with log(vapor pressure) as an additional predictor (p > 0.05), so vapor pressure appears not to explain the significant in vivo/PCR‐vitro discrepancy. Until this discrepancy is explained, careful in vivo measures of K_up should be obtained for more chemicals, the expanded in vivo database should be compared to in vitro‐based predictions, and in vivo data should be considered in assessing aqueous dermal exposure and its uncertainty.     

Systems Resilience for Multihazard Environments: Definition,Metrics, and Valuation for Decision Making

The United Nations Office for Disaster Risk Reduction reported that the 2011 natural disasters, including the earthquake and tsunami that struck Japan, resulted in $366 billion in direct damages and 29,782 fatalities worldwide. Storms and floods accounted for up to 70% of the 302 natural disasters worldwide in 2011, with earthquakes producing the greatest number of fatalities. Average annual losses in the United States amount to about $55 billion. Enhancing community and system resilience could lead to massive savings through risk reduction and expeditious recovery. The rational management of such reduction and recovery is facilitated by an appropriate definition of resilience and associated metrics. In this article, a resilience definition is provided that meets a set of requirements with clear relationships to the metrics of the relevant abstract notions of reliability and risk. Those metrics also meet logically consistent requirements drawn from measure theory, and provide a sound basis for the development of effective decision‐making tools for multihazard environments. Improving the resiliency of a system to meet target levels requires the examination of system enhancement alternatives in economic terms, within a decision‐making framework. Relevant decision analysis methods would typically require the examination of resilience based on its valuation by society at large. The article provides methods for valuation and benefit‐cost analysis based on concepts from risk analysis and management.     

UNIX系统性能监控简述及shell系统资源统计程序

本文简要阐述了unix系统中(主要以IBM的AIX为例)进行系统性能管理的几种命令行工具,并通过编写shell实例程序,运用其中提到的工具实现系统资源利用率的统计程序,为做好unix系统管理和调优提供参考.