Estimation of a multiple-threshold AR(p) model

The present paper deals with the multiple-threshold p-order autoregressive model which has been introduced by Tong and Lim [H. Tong, K.S. Lim, Threshold autoregression, limit cycles and cyclical data, J. R. Stat. Soc. Ser. B 42 (1980) 245–292] in nonlinear system modelling. Under some conditions on the coefficients of the model which ensure the stationarity, the existence of moments and the strong mixing property of this process and under other mild assumptions, we establish the asymptotic properties (consistency and asymptotic normality) of the minimum Hellinger distance estimates of the autoregressive coefficients of the model.     

Does Security Impact E‐procurement Performance? Testing a Model of Direct and Moderated Effects

Despite the widespread adoption of e‐procurement and the critical role of information security in these situations, academic research examining the relationship between information security and e‐procurement performance has been surprisingly minimal. This study represents an interdisciplinary approach to present and test a theoretical model that links security in e‐procurement processes to e‐procurement performance. E‐procurement performance is measured as a combination of cost savings, order quality, and satisfaction of fulfillment as perceived by buyers. The model also posits that two aspects of the procurement process will enhance the value of security in e‐procurement, namely, process complexity and process interdependence. We empirically examine these relationships using data collected from procurement managers. Our results have important implications for managing the e‐procurement process.     

碳排放交易机制中涵盖部门制度的构建

碳排放交易机制是减缓温室气体排放的重要经济手段,其首要环节是确定涵盖部门范围,以及排放实体或设施的纳入门槛。环境效果与经济效率是涵盖部门制度设计的重要价值考量。在理论上,涵盖的部门范围越广泛,纳入的排放单位越多,其环境效果和经济规模效应越显著。但在实践中,一些产业部门根据经济可行性分析、技术因素的考虑以及减排激励的差异,会有其他更加合适的减排选项。     

FDI对中国出口贸易的影响与区域差异实证研究

外商直接投资和出口增长对一个国家或地区经济增长起着重要作用,是国家或地区经济发展的重要推动因素之一。对FDI与出口贸易影响程度进行实证研究,将我国各省市根据区域划分为东、中、西三个横截面,利用2001至2009年九年数据建立面板数据模型,集中对我国FDI与出口间关系,东、中、西三地区FDI与出口关系进行实证研究,比较不同区域影响程度。     

中国区域能源消费的决定因素及空间溢出效应———基于空间面板数据计量经济模型的实证

应用空间面板计量经济模型分析了中国各省域的能源消费行为、决定因素及其空间溢出效应.研究显示,我国各个省域的能源需求主要由产业结构、经济增长和人口增长等因素决定,价格机制在调控能源需求方面还未能发挥出应有的作用.应用空间滞后面板计量经济模型和空间误差面板计量经济模型对区域能源消费行为的空间溢出效应进行分析检验证实:邻近区域的能源消费行为未能影响到本地区的能源消费,但能源利用效率等被忽略的因素对邻近区域的能源消费行为具有很强的溢出效应.     

The achievable region approach to the optimal control of stochastic systems

The achievable region approach seeks solutions to stochastic optimization problems by characterizing the space of all possible performances (the achievable region) of the system of interest and optimizing the overall system-wide performance objective over this space. This is radically different from conventional formulations based on dynamic programming. The approach is explained with reference to a simple two-class queueing system. Powerful new methodologies due to the authors and co-workers are deployed to analyse a general multi-class queuing system with parallel servers and then to develop an approach to optimal load distribution across a network of interconnected stations. Finally, the approach is used for the first time to analyse a class of intensity control problems.     

Employee absence, age and tenure: a study of nonlinear effects and trivariate models

Multiple regression techniques were used to explore the nature of the relationships between age, tenure and absence in 2417 British local government workers drawn from three work groups. The data were collected from organizational records and included measures of both non-certified absence and medically certified absence. Linear and curvilinear associations among age, tenure and absence were examined. The possible moderating or mediating role of tenure in the relationship between age and absence was subsequently analysed. The data revealed linear relationships between age and absence that were negative for non-certified absence and positive for certified absence. In contrast, curvilinear relationships were found between tenure and absence that were U-shaped for noncertified absence and inverse U-shaped for certified absence. Tenure was found to moderate but not to mediate the relationship between age and absence. The implications of the results are discussed in the context of the changing age and career paths of the workforce, and of methodological issues in absence research.     

关于高校双语教学的思考

论述了高校双语教学的意义和目标,指出了高等学校开展双语教学所面临的困难。对双语教学的形式、教材选择和加强双语教学的措施进行了深入研究,同时指出了双语教学的负面影响。     

The Economics of Public Beta Testing

A growing number of software firms now rely on public beta testing to improve the quality of their products before commercial release. While the benefits resulting from improved software reliability are well recognized, some important market‐related benefits have not been studied. Through word‐of‐mouth, public beta testers can accelerate the diffusion of a software product after its release. Additionally, because of network effects, public beta testers can increase users’ valuation of a product. In this study, we consider both reliability‐related and market‐related benefits, and develop models to determine the optimal number of public beta testers and the optimal duration of testing. Our analyses show that public beta testing can be profitable even if word‐of‐mouth and network effects are the only benefits. Furthermore, when both benefits are considered, there is significant “economies of scope”—the net profit increases at a faster rate when both word‐of‐mouth and network effects are significant than when only one benefit is present. Finally, our sensitivity analyses demonstrate that public beta testing remains highly valuable to software firms over a wide range of testing and market conditions. In particular, firms will realize greater profits when recruiting public beta testers who are interested in the software but unable to afford it.     

A threshold autoregressive model for wholesale electricity prices

Summary.  We introduce a discrete time model for electricity prices which accounts for both transitory spikes and temperature effects. The model allows for different rates of mean reversion: one for weather events, one around price jumps and another for the remainder of the process. We estimate the model by using a Markov chain Monte Carlo approach with 3 years of daily data from Allegheny County, Pennsylvania. We show that our model outperforms existing stochastic jump diffusion models for this data set. Results also demonstrate the importance of model parameters corresponding to both the temperature effect and the multilevel mean reversion rate.