搜寻成本、声誉与网上交易市场价格离散

基于搜寻理论,探讨了当网上交易市场中卖家声誉以及买家保留价格之间存在差异时,搜寻成本对均衡价格水平和离散程度的影响,进而研究了声誉同搜寻成本之间的相互作用.研究表明:较高的搜寻成本使得不同声誉水平的卖家可以同时存在于网上交易市场;为了同高声誉卖家展开竞争,低声誉卖家不得不将产品的价格降低,从而导致网上交易市场产品价格的离散化;不同保留价格的买家付出不同的搜寻活动,并随着搜寻效率的提高,市场均衡价格不断降低;最终,低声誉卖家将被逐出网上交易市场.此外,高声誉卖家通过提供广告推广活动提高了买家的搜寻效率,使得买家搜寻活动有所减少,从而买家愿意为高声誉卖家支付较高的价格,导致市场价格离散加剧.     

网上拍卖中卖者声誉的价值：以邮票类物品为例

采用一个简单的重复博弈模型分析了网上拍卖市场中卖方声誉的价值,并利用从淘宝和eBay网站收集的邮票类物品的竞价数据,实证检验了卖方信用度对拍卖物品成交概率和成交价格的影响.研究结果表明,卖方在网上拍卖市场建立良好的声誉是富有价值的,并且其价值将主要体现在显著增加了物品的成交概率上.相对而言,卖方信用度对物品成交价格的影响不显著.     

信用评价体系以及相关因素对一口价网上交易影响的实证研究

利用淘宝网的交易数据,研究一口价价格、信用的好中差评、商盟以及消费者保障计划等对交易笔数的影响。实证研究表明,价格对交易笔数有显著的负影响、好中差评数均有显著的正影响,而是否参加商盟无显著影响,参加消费者保障则为卖家带来了更多的交易笔数。研究表明,信用评价体系在网上交易中起到了一定的作用,但这个作用受到淘宝的信用评价政策等诸多因素的影响。     

关于双向声誉机制的作用机理及有效性研究

通过建立博弈论模型比较了双向声誉机制中的同步声誉机制和非同步声誉机制在实现诚实评价方面的有效性.结论表明,当买家严格偏好惩罚某种类型的卖家时,非同步声誉机制产生的评价不能真实反映坏的交易结果,如果要让非同步声誉机制实现诚实评价,则需要增加诸多约束条件.另一方面,同步声誉机制能够实现诚实评价,而且当买家严格偏好惩罚某种类型的卖家时,诚实评价还是同步声誉机制唯一的均衡.     

网上拍卖交易机制有效性研究——来自淘宝网面板数据的证据

本文考察了淘宝网上信任保障和购物搜索两类交易机制的有效性.网上拍卖的交易机制越来越完善,除了信用度和好评率等基本信用指标外,网站先后建立了卖家服务质量、店铺动态评分、搜索排序等重要交易机制,本文利用淘宝网上的面板数据来验证上述机制的有效性.回归结果表明,信用度作为网上拍卖最早引入的一项信用指标仍发挥着一定的作用;店铺动态评分和卖家服务质量没有发挥应有的作用.进一步的解释是:网上市场存在较高的搜寻成本,买家利用搜索排序来降低搜寻成本,信用度的重要性因而被信用度排序放大;买家无法根据店铺动态评分和卖家服务质量进行筛选排序,导致这两大机制没有发挥应有作用.购物搜索在网上交易中发挥着重要作用,信任机制依赖搜索工具发挥作用.除混合数据OLS回归外,本文还利用面板数据和联立方程回归分析控制了遗漏变量偏误和内生性问题.     

平台收费对网上交易市场价格离散的影响

基于搜寻理论,探讨了网上交易平台向卖家和买家收费,对均衡价格水平和离散程度的影响,建立了单期博弈模型．运用最优化理论分别求得了仅向卖家收费和向卖家与买家都收费情况下的买家最优搜寻活动、均衡价格以及价格离散程度．研究表明: 交易平台收费将导致买家减少搜寻活动; 当交易平台仅向卖家收费时,两类卖家均提高定价,而随着收费金额的提高,网上交易市场中价格离散程度降低; 当交易平台向卖家和买家同时收费时,高声誉卖家的定价降低,低声誉卖家的定价提高,市场均衡时,价格离散程度进一步降低,乃至消失．     

C2C网上交易中信号机制的有效性分析

本文应用Berry等(1995)^[2]提出的离散选择需求模型和差异产品的伯川德竞争模型,并利用淘宝网上的交易数据,对声誉、消费者保障计划、保修服务及信息披露四种信号策略在网上交易中的作用进行了实证研究。需求估计结果表明消费者保障计划中的"7天无理由退换货"计划以及保修服务可以作为产品质量的信号;而在其他有效信号策略存在的情况下,消费者保障计划中的"先行赔付"计划以及卖家声誉作为质量信号的作用则被削弱。成本分析表明,信息披露虽然可以提高消费者购买的可能性,但是由于发出信号的成本太低,容易被低质量卖家所模仿,因此并不能作为有效的质量信号。本文首次从供给和需求两个方面分析了信号机制在信息不对称情况下的效应及其作用机制。     

卖方商盟与网络诚信：基于跨域协调的视角

本文认为引入卖方商盟制度,使在线卖方同时处于B2C的经济交易域和B2B的社会交换域中,通过在两个域的联合博弈,特别在社会交换域的联合制裁作用机制下,在线卖方在经济交易域中的欺诈动机比引入商盟制度前有所降低。正是基于这种预期,消费者更加信任商盟中的在线卖方。     

媒体监督、声誉共同体与投资者保护

声誉是一种重要的投资者利益保护机制,但相对于法律机制,有关研究却相对滞后。本文以声誉理论为基础,从整体和动态的角度,创造性地提出声誉共同体概念,构建了媒体监督下声誉对投资者利益保护机制的研究框架,并以五粮液为例对此框架进行解析。通过本文建立的声誉受损成本模型,以声誉受损成本在共同体成员之间的传递,解释了声誉机制的作用机理,并揭示了声誉机制作用效果存在差异的原因。     

独立董事声誉与盈余质量——会计专业独董的视角

本文研究中国上市公司独立董事声誉对盈余质量的影响。本文以2007~2012年我国民营上市企业为样本,从会计专业独董的视角研究独立董事声誉对盈余质量的影响。研究发现,会计专业独董的声誉对企业盈余质量有着显著的正向影响,并且这种影响在受聘于大股东掏空严重、低市场化进程地区企业和担任审计委员会主席的高声誉会计专业独董上更为明显。本文的结论在使用不同的盈余质量度量方式、不同的独董声誉度量方式、控制了内生性因素后依然成立。本文的结果表明,高声誉的会计专业独董能积极发挥治理作用,提高盈余质量。本文为独立董事声誉的研究提供了一个新的视角,即声誉机制能激励独立董事维持其独立性,提高公司的会计信息披露质量,从而保护中小股东利益,这对于当前我国不够完善的投资者法律保护体系以及公司治理机制是一种有效的补充。     

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.     

Introduction to Special Section on Sensitivity Analysis and Summary of NCSU/USDA Workshop on Sensitivity Analysis

This guest editorial is a summary of the NCSU/USDA Workshop on Sensitivity Analysis held June 11–12, 2001 at North Carolina State University and sponsored by the U.S. Department of Agriculture's Office of Risk Assessment and Cost Benefit Analysis. The objective of the workshop was to learn across disciplines in identifying, evaluating, and recommending sensitivity analysis methods and practices for application to food‐safety process risk models. The workshop included presentations regarding the Hazard Assessment and Critical Control Points (HACCP) framework used in food‐safety risk assessment, a survey of sensitivity analysis methods, invited white papers on sensitivity analysis, and invited case studies regarding risk assessment of microbial pathogens in food. Based on the sharing of interdisciplinary information represented by the presentations, the workshop participants, divided into breakout sessions, responded to three trigger questions: What are the key criteria for sensitivity analysis methods applied to food‐safety risk assessment? What sensitivity analysis methods are most promising for application to food safety and risk assessment? and What are the key needs for implementation and demonstration of such methods? The workshop produced agreement regarding key criteria for sensitivity analysis methods and the need to use two or more methods to try to obtain robust insights. Recommendations were made regarding a guideline document to assist practitioners in selecting, applying, interpreting, and reporting the results of sensitivity analysis.     

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.     

Distinguishing traumatic, vicarious and routine operational stressor exposure and attendant adverse consequences in a sample of police officers

Problems in studying occupational stress within the police service are identified and the paucity of work on operational duties as potential stressors are discussed. The present study reports the results of a factor analysis of operational stressors (N = 601 serving British police officers) that revealed three factors: exposure to death and disaster; violence and injury; sexual crime. These were demonstrated to be reliable scales and were included in logistic regression models together with a range of demographic and psychological variables. Models were applied to men and women separately, which showed there to be different predictors of the likelihood of suffering distress (measured by the General Health Questionnaire, GHQ) in terms of the officer's gender and operational role. Overall the model for women officers was better at predicting psychological distress than that for men. These findings are related to aspects of the police occupational culture. Further discussion is offered that conceptualizes police operational stressors as traumatic, routine and vicarious. Finally, some implications are drawn for the provision of stress intervention in the light of this differentiation.     

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.