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.     

中国航空货运顾客价值动因的实证研究

通过考察中国航空货运,建立航空顾客价值的决定因素与动态性理论模型,运用结构方程方法对其检验,结果表明:时间因素和便捷性因素是影响货运顾客价值的核心要素,价格因素已退之其次,而且来自竞争者、服务商、顾客、宏观环境的变化都对顾客价值动态性有显著影响。     

Using replication research for just-in-time purchasing construct development

Using replication research, the validity of the just-in-time purchasing (JITP) construct is established. Although empirical researchers have examined JITP over the last two decades, a consistent set of valid, reliable factors has not been used. The lack of valid construct is a barrier to hypotheses testing and meta-analyses on JITP. This study confirmed the validity of six JITP factors: top management commitment, employee relations, training, supplier quality management, transportation, and quantities delivered using two different data sets and testing the first- and second-order structure of the JITP construct. Content validity, reliability, unidimensionality, convergent validity, discriminant validity, criterion-related validity, and an invariant factorial structure of the JITP construct were empirically established.     

试论波特劳勒“综合激励模型”的应用

知识型员工是知识经济时代出现的新型工作群体熏他们是知识资本的掌握者,是企业最为宝贵的资源熏文章通过对波特劳勒综合激励模型理论的分析认为:对知识型员工的激励熏应建立在满足其较高层次需要的基础上熏在激励策略方面熏主要采取报酬激励、精神激励和工作激励等方式熏并且应根据知识型员工不同的特点,选择不同的激励方式组合,才能充分发挥知识型员工的工作积极性。     

外生冲击与房地产真实价格波动--对1998～2003年中国31省(市、区)的实证研究

文章首先根据经济学模型界定了两个重要指标:自相关系数与收敛系数.认为不同的外生冲击对这两个系数有不同的影响,而它们决定了房地产真实价格波动形态的差异.在此基础上,文章利用1998～2003年中国31个省(市、区)的面板数据对中国房地产市场进行了实证研究,其结论是,在真实人均可支配收入和真实建筑成本较高、真实税后住宅抵押贷款利率较低的地区有较大的自相关系数和较小的收敛系数,从而房地产真实价格具有更大的波动性.为使房地产真实价格在均衡价格附近平稳运行,降低开发成本和提高消费者购买成本能收到较好的效果.     

“Itô's Lemma” and the Bellman Equation for Poisson Processes: An Applied View

Using the Hamilton-Jacobi-Bellman equation, we derive both a Keynes-Ramsey rule and a closed form solution for an optimal consumption-investment problem with labor income. The utility function is unbounded and uncertainty stems from a Poisson process. Our results can be derived because of the proofs presented in the accompanying paper by Sennewald (2006). Additional examples are given which highlight the correct use of the Hamilton-Jacobi-Bellman equation and the change-of-variables formula (sometimes referred to as ``Itô's Lemma'') under Poisson uncertainty.     

Recursive utility with unbounded aggregators

A new framework is presented for the study of the existence and uniqueness of solutions to the Koopmans’ equation in the unbounded case, that is based on the contraction mapping approach. In the bounded below case with bounded consumption streams, uniqueness of the solution in the whole class of weak-star continuous utility functions is obtained. When the aggregator is unbounded below and/or consumption streams are unbounded, existence of a weak-star continuous solution is shown, and a simple criterium to check the sufficient conditions for existence is provided. Juan Pablo Rincón-Zapatero and Carlos Rodríguez-Palmero gratefully acknowledge financial support by the Ministerio de Educación y Ciencia and FEDER funds under Research Projects MTM2005-06534 and SEJ2005-08709/ECON, respectively, and by Consejería de Educación de la Junta de Castilla y León under Research Projects VA99/04 and VA017B05, respectively. This paper has substantially benefited from the comments of an anonymous referee. Particular and special thanks are due to Robert Becker for his very helpful comments and valuable suggestions.     

企业信息化项目管理对项目成功的影响研究

在企业信息化项目中,项目管理是企业深化改革和提高信息化效益的重要途径。但是项目管理究竟在项目建设中发挥了多大作用,对项目成功起到了怎样的影响,这一直以来都是一个模糊的概念。文章通过问卷调查和结构方程模型具体衡量项目管理对项目成功的影响程度。     

基于主成分分析的多元线性回归用水量模型研究——以安徽省为例

用水量的准确预测对水资源规划具有重要意义。根据统计资料,选取了八项主要影响用水量变化的指标。按照主成分分析法原理,运用少数综合因子对影响用水量变化的原有八项指标进行了综合和简化,并研究其贡献率及综合效应;分析了用水量增长的特点,选用Logistic方程对综合因子进行回归分析;结合多元线性回归方法,建立了安徽省用水量模型;拟合结果表明,模型具有较高的精度;运用该模型,对安徽省2010年的用水量进行了预测;为水资源规划与管理提供参考依据。     

紧凑城市与可持续发展的中国实证

中国城市发展是走郊区化之路,还是高密度的紧凑城市之路,取决于紧凑城市是否有利于可持续发展。文章以紧凑城市与可持续发展的关联机制为基础,提出相应的测度指标,利用回归模型、典型相关分析方法对两者的关联性进行实证研究,结果发现城市越紧凑越有利于经济、环境和社会的可持续发展,但并未引起资源消耗的显著改善。结论对于我国建设紧凑型城市、促进可持续发展无疑具有重要的政策启示。