MSE-improvement of the least squares estimator by dropping variables

It is well known that dropping variables in regression analysis decreases the variance of the least squares (LS) estimator of the remaining parameters. However, after elimination estimates of these parameters are biased, if the full model is correct. In his recent paper, Boscher (1991) showed that the LS-estimator in the special case of a mean shift model (cf. Cook and Weisberg, 1982) which assumes no “outliers” can be considered in the framework of a linear regression model where some variables are deleted. He derived conditions under which this estimator outperforms the LS-estimator of the full model in terms of the mean squared error (MSE)-matrix criterion. We demonstrate that this approach can be extended to the general set-up of dropping variables. Necessary and sufficient conditions for the MSE-matrix superiority of the LS-estimator in the reduced model over that in the full model are derived. We also provide a uniformly most powerful F-statistic for testing the MSE-improvement.     

基于交易成本经济学的企业业务外包分析

企业业务外包是近年来在国外兴起的一种经营行为,它的目的是降低成本,提高企业的竞争力。目前中国很多企业也纷纷在尝试这一做法。然而不是任何企业,任何业务都适合外包。本文将从交易成本经济学的角度来对企业业务外包这一行为进行分析,提出适宜进行业务外包的情况,并说明进行业务外包时应该注意的问题。     

Thermodynamics and process analysis for future economic scenarios

Economists are increasingly interested in forecasting future costs and benefits of policies for dealing with materials/energy fluxes, polluting emissions and environmental impacts on various scales, from sectoral to global. Computable general equilibrium (CGE) models are currently popular because they project demand and industrial structure into the future, along an equilibrium path. But they are applicable only to the extent that structural changes occur in or near equilibrium, independent of radical technological (or social) change. The alternative tool for analyzing economic implications of scenario assumptions is to use Leontief-type Input-Output (I-O) models. I-O models are unable to endogenize structural shifts (changing I-O coefficients). However, this can be a virtue when considering radical rather than incremental shifts. Postulated I-O tables can be used independently to check the internal consistency of scenarios. Or I-O models can be used to generate scenarios by linking them to econometric macro-drivers (which can, in principle, be CGE models). Explicit process analysis can be integrated, in principle, with I-O models. This hybrid scheme provides a natural means of satisfying physical constraints, especially the first and second laws of thermodynamics. This is important, to avoid constructing scenarios based on physically impossible processes. Process analysis is really the only available tool for constructing physically plausible alternative future I-O tables, and generating materials/energy and waste emissions coefficients. Explicit process analysis also helps avoid several problems characteristic of pure CGE or I-O models, viz. (1) aggregation errors (2) inability to handle arbitrary combinations of co-product and co-input relationships and (3) inability to reflect certain non-linearities such as internal feedback loops.     

论风险投资中的尽职调查

通过对20多位风险投资家的调研,对他们尽职调查所必备的条件、策略及过程进行了系统分析,总结出其内在规律,以期对我国风险投资项目的筛选有所启示.     

Evolution of momentum and popularity

In this paper, the evolutionary behavior of two types of investor in a capital market with two risky competing securities is investigated. It is shown that, if all investors are momentum-oriented, then only those who are the most sensitive to popularity will survive. Conversely, if all investors are popularity-oriented, then they will all invest in the same security.     

呋喃酚的合成方法

根据原料的不同,呋喃酚合成方法可分为邻苯二酚法、邻氯苯酚法、环己酮法、硝基苯酚法、愈创木酚法、邻异丙基酚法、羟基苯异酮法等,文章对前几种较常见的合成方法的原理及工艺进展进行了详细的综述,并展望了呋喃酚合成方法的发展趋势。     

审计判断的成因及其在审计过程中的应用

审计专业判断是审计人员职业道德、胜任能力和专业经验的有机统一和外在表现,当审计人员面对复杂审计事项和不确定审计环境时,正确的审计判断是审计人员能否作出合理认识、评价、预测和决策的必要条件,也是审计能否成功的关键因素。本文从审计判断的特征、成因入手,探讨了在现代审计模式下审计判断在审计过程中的应用问题。     

Making green discourses matter in policy-making: Learning from discursive power struggles within the policy area of car taxation

This paper is about stability and change in the policy-making discourse of a traditional neoclassical policy area, the area of car taxation. Stability is here related to the unquestioned continuation of a traditional neoclassical economics perspective in policy-making, whereas change is related to the introduction and impact of environmental concerns. The aim of the paper is to investigate, what makes green discourses matter in traditional policy-making. It is based on an in-depth study of policy-making processes related to car taxation in two environmental front-runner countries, Sweden and Denmark.Making green discourses matter in policy-making is an important contemporary environmental challenge. Therefore, as Tian Shi argues, we need more research into the institutional setting of the policy-making process. Ecological economics as a policy science has to have a broad understanding of the political economic nature of the policy process. Taking this standpoint as the point of departure, the paper seeks to uncover questions such as, what is the policy-making reality in which Swedish and Danish green discourses have to make a difference? How do existing neoclassical regimes react, when green actors attempt to influence policy-making from an environmental point of view? And to what extent can green discourses actually have an impact on the policy world within the area of car taxation?The paper concludes that the traditional neoclassical economic discourse is particularly robust and resistant against alternative green discourses. Stability rather than change is the dominating picture. This does not imply that environmental concerns will not be taken into account in the future. Rather it implies that only the changes, which keep up the existing order, or enhance the narrow power-related interests of the dominating actors, will materialise more or less easily. The rest is a power struggle in which timing, coalition-building, persistence and thorough knowledge about the field in question is of importance. In this struggle change agents will also benefit from the ability to rethink dominating ways of thinking and doing in an environmentally benign way. A rethinking that is based on environmental values while at the same time holding positive visions that are ‘compatible’ with the existing dominating discourse.     

迁移理论的基础:“理解人口学”的分析框架

根据学者布如金所提出的人口理论研究新范式,在对其进行概括和拓展的基础上,提出了“理解人口学”的分析框架。同时综合部分迁移研究的成果,融合不同研究方法,从四个层次:迁移行为的概念假设、迁移行为的发端、迁移行为的外部环境和迁移行为的时间纬度,为人口迁移行为分析提供了-个跨学科的研究视野。     

中国经济体制改革时期制度变迁的特征分析

从实质上说，中国经济体制改革的过程就是一个制度的重建过程，即以适应市场经济的制度安排取代适应计划经济的制度安排取代适应计划经济的制度安排的过程。在这一制度重建的进程中，市场取向的制度变迁表现出八个方面的典型特征：一是制度变迁需求的内性性；二是制度变迁供给的滞后性；三是制度变迁目标的动态性；四是制度变迁过程的渐进性；五是制度变迁轨迹的路径依赖性；六是从单项制度变迁向制度结构变迁演进；七是强制性制度变迁与诱致性制度变迁相结合；八是宏观经济制度变迁与微观经济制度变迁同步进行。