数据拟合回归方法的探讨

建立回归方程进行分析预测,大多采用人们熟知的"最小二乘法"。但是"最小二乘法"有本质上的一个弱点,由于系数矩阵的病态性质:系数矩阵中的最大值相对很大,系数矩阵的行列式值相对较小,在求解方程时,系数中的微小变化可能导致结果不稳定,预测效果不佳甚至失真。本文另辟蹊径,与"最小二乘法"的拟合原则不同,我们是最小化误差绝对值中的最大值。该法克服了"最小二乘法"有时不稳定的缺陷,继而提高拟合精度,使预测效果更精确。     

房地产价格波动与投机行为--对中国14城市的实证研究

本文首先构建了适合中国的房地产投机理论模型,然后利用该模型对中国14个城市房地产价格波动与投机行为的关系进行实证研究.对14城市的时间序列数据研究结果表明各城市房地产投机水平都很高,个别城市更加突出.通过对14城市的截面数据分析,可以看出可支配收入对房地产价格没有显著影响,这些城市房地产价格的上升,主要是由投机来推动的,而且整体投机度非常高,说明房地产价格极大的偏离长期均衡值,市场出现了非理性繁荣,政府和产业部门应该采取适当的措施,积极引导消费者和投资者,为建立均衡的房地产市场提供良好的宏观和微观环境.     

Is Private R & D Spending Sensitive to Its Price? Empirical Evidence on Panel Data for Italy

In this paper empirical evidence is presented on theelasticity of private R & D spending on its price. Acensored panel-data regression model with random effectsis applied to a balanced panel of 726 Italian firms overthe 1992–1997 period. Implied estimates point out thatItalian firms' response to policy measures (including taxcredits), aimed at reducing the user cost of R & D capital,is likely to be substantial (1.50–1.77). Furthermore, wealso find that the elasticity of R & D spending is higherin recession (2.01) than in expansion (0.87).     

城市森林固定CO2价值评估

本文利用我国第四次森林资源清样调查资料对上海市森林植被碳储量和碳密度的估算结果,结合植物的光合作用过程计算上海市森林固定CO2的能力,采用造林成本法对上海市森林固定CO2的价值进行了评估。笔者希望通过该研究激发人们保护城市森林以维持城市生态系统可持续发展的积极性,并为合理地进行城市森林管理和城市绿化提供参考。另外,利用系统连续的森林资源清样调查资料评估森林植被的固碳价值,能够对我国更好地履行《联合国气候变化框架公约(》UNFCCC),并为依据《京都议定书(》KyotoProtocol)进行环境外交提供帮助。     

Comparison of Hypothesis Testing and Bayesian Model Selection

The main goal of both Bayesian model selection and classical hypotheses testing is to make inferences with respect to the state of affairs in a population of interest. The main differences between both approaches are the explicit use of prior information by Bayesians, and the explicit use of null distributions by the classicists. Formalization of prior information in prior distributions is often difficult. In this paper two practical approaches (encompassing priors and training data) to specify prior distributions will be presented. The computation of null distributions is relatively easy. However, as will be illustrated, a straightforward interpretation of the resulting p-values is not always easy. Bayesian model selection can be used to compute posterior probabilities for each of a number of competing models. This provides an alternative for the currently prevalent testing of hypotheses using p-values. Both approaches will be compared and illustrated using case studies. Each case study fits in the framework of the normal linear model, that is, analysis of variance and multiple regression.     

Simulation driven inferences for multiply imputed longitudinal datasets*

In this article, we demonstrate by simulations that rich imputation models for incomplete longitudinal datasets produce more calibrated estimates in terms of reduced bias and higher coverage rates without duly deflating the efficiency. We argue that the use of supplementary variables that are thought to be potential causes or correlates of missingness or outcomes in the imputation process may lead to better inferential results in comparison to simpler imputation models. The liberal use of these variables is recommended as opposed to the conservative strategy.     

面向电子商务的现代物流管理信息系统的开发

结合现代物流技术发展趋势，分析探讨了面向电子商务的现代物流管理信息系统的开发技术路线，关键技术内容，功能体系结构设计及分层逻辑模型设计。     

基于高频数据的深圳基金市场日内周期性研究

本文利用深市基金指数高频数据,采用Anderson和Bollerslev(1997)提出的弹性傅立叶回归(FlexibleFourierFormregression,即FFF回归)方法首次对深市基金市场进行了日内周期性的研究。通过对高频收益的定性分析,发现基金市场具有同股票市场相似的周期性,并对这一周期性进行了初步的理论解释。通过FFF方法,将该周期因子进行滤波处理以后,基金指数高频绝对收益不再具有明显周期性。FFF回归能较好地确定日内周期因子。     

市场化与经济增长:一个短期的因果关系检验

利用我国1999-2002年省际区域的面板数据,运用面板数据Granger因果关系检验技术,对我国市场化水平与经济增长的关联度进行了实证分析.得出市场化是经济增长的Granger原因,但是经济增长不是市场化的Granger原因的结论.     

Knowledge integration via the fusion of the data models used in automotive production systems

ABSTRACT

In this paper a novel information model that can be used in Manufacturing Execution Systems is presented. The model is based on the fusion of ISA95, AML and OPC UA. ISA95 is used to define, unify and describe the details of a product and production technology. It also enables communication with ERP systems. The AML standard allows information about the production facilities to be presented. The OPC UA address space represents different parts of an information model while the OPC communication protocol enables it to be linked to actual production systems. The proposed concept is illustrated using an actual example of a production line for electronic devices.