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.     

Distinguishing external from internal scale effects: The case of public infrastructure

The recent applied production theory literature focusing on the economic performance of firms has increasingly recognized the importance of scale effects on costs and therefore efficiency. These scale effects may include short run returns due to fixity of privately demanded inputs (i.e., capital, long run internal returns to scale, and external factors affecting costs. Since these different types of scale effects can be thought of as shifts in and movements along cost curves, the different cost effects of such factors can be identified in a framework which explicitly takes them into account in the definition ofscale.In this article we formalize such a framework, and then use it to measure short run, long run (internal) and external scale effects from fixity of private capital, nonconstant returns to scale and public infrastructure. We then use these measures to identify the impacts of these different scale factors on productivity growth. The focus on public infrastructure as an important external scale factor is motivated by the current theoretical and policy interest in this issue; we show how a structural production theory model provides a rich basis for the analysis of the cost effects of infrastructure investment.     

集群中小企业发展的关键

在激烈的市场竞争中，单个中小企业在经营中困难重重。集群这种企业间组织新形式，可以发挥我国众多中小企业的优势，在不牺牲经营柔性的前提下，实现规模经济，降低经营成本。     

乡镇经济和环境可持续发展的矛盾与对策

目前江苏乡镇企业造成的环境污染日益严重。本文从产业结构、行业结构、技术结构、环境管理、环保投入水平等九个方面分析了乡镇工业严峻形势形成的根源。指出，迫切需要把乡镇企业环境管理作为全省的一个环保战略重点，并采取有效措施，保护乡镇生态环境。     

Limit-pricing as Bertrand equilibrium

Summary. We consider a Bertrand duopoly model with increasing returns to scale where one of the firms have a cost advantage and prices vary over a grid. We find that typically more than one equilibria exist. However, there are only two perfect equilibria. Moreover, as the size of the grid becomes small, both these equilibria converge to the limit-pricing outcome. Received: February 25, 2000; revised version: January 9, 2001     

嘉兴市产业结构与地区经济增长

该文通过实证研究，分析和度量嘉兴市不同产业对地区经济增长的作用，探讨各产业是以何种方式影响经济增长的，旨在为今后嘉兴市制定产业政策提供决策依据。     

风险资本规模与最优投资组合

对于任何一个风险投资基金来说,都涉及到投资组合规模问题。由于在投资策略中奉行积极干预的策略,风险投资家耗费了大量的精力和时间。因此,风险资本规模的扩大对风险投资家的投资结构可能会产生影响。这就引致出风险投资最优投资组合的问题,并涉及对风险投资收益率的影响。     

四大国有商业银行的收缩战略研究——从规模经济的角度探讨银行实施收缩战略的必要性

在不断出现的全球银行业并购案例中 ,人们往往只重视对商业银行的扩张战略进行研究 ,但是收缩战略在当今的银行业中同样发挥着重要的作用。本文首先通过对银行业的背景和银行适度规模的分析 ,探讨商业银行实施收缩战略的原因 ,然后从实证的角度对我国国有商业银行的规模及其效益进行分析 ,证明实施收缩战略的必要性。文章最后针对我国的现实情况 ,提出实施收缩战略的两点具体措施。     

A DEA Approach to Understanding the Productivity Growth of Malaysia's Manufacturing Industries

This paper seeks to explain the productivity growth performance of Malaysia's manufacturing sector using a panel data of 28 industries from 1981–1996. Here, the data envelopment analysis technique is used to calculate and decompose the Malmquist index of total factor productivity (TFP) growth into technical change, change in technical efficiency and change in scale efficiency. This allows the identification of the sources of productivity growth which is crucial for policy formulation. It was found that the annual TFP growth of the Malaysian manufacturing sector was low at 0.8% and this was driven by small gains in both technical change and technical efficiency, with industries operating close to optimum scale.     

中国银行业规模经济和范围经济的实证研究——基于复合成本函数的分析

本文首次在国内利用复合成本函数估计我国国有商业银行和股份制商业银行1998——2003年的成本函数,并计算出各自的规模经济和范围经济。复合成本函数把投入价格的对数二次项和产出的二次项结合起来,具有优良的实证研究性质。实证研究结果表明:时间对我国银行业的规模经济和范围经济影响不显著;国有商业银行和股份制商业银行都存在着轻微的规模不经济和范围不经济,国有银行略好于股份制银行。我国商业银行的两种产出——存款和贷款不存在成本互补性。