从人力资本投资看我国的城乡收入差距

本文从人力资本投资的角度探讨影响城乡收入差距的因素,通过1990年和2000年的省际截面数据分析,得出的基本结论是:基础教育的普及程度比较高,在城乡之间的普及没有太大的差距,因此不是形成城乡收入差距的原因;而高等教育的人力资本投资的增加在1990年会降低城乡收入差距;2000年二者的关系为"U"型关系,即开始阶段规模的扩大会降低城乡收入差距,随着高等教育规模的不合理和无序扩大,反而会引起城乡收入差距的扩大。     

Evaluating Projects and Assessing Sustainable Development in Imperfect Economies

We are interested in three related questions:(1) How should accounting prices be estimated?(2) How should we evaluate policy change in animperfect economy? (3) How can we check whetherintergenerational well-being will be sustainedalong a projected economic programme? We do notpresume that the economy is convex, nor do weassume that the government optimizes on behalfof its citizens. We show that the same set ofaccounting prices should be used both forpolicy evaluation and for assessing whether ornot intergenerational welfare along a giveneconomic path will be sustained. We also showthat a comprehensive measure of wealth,computed in terms of the accounting prices, canbe used as an index for problems (2) and (3)above. The remainder of the paper is concernedwith rules for estimating the accounting pricesof several specific environmental naturalresources, transacted in a few well knowneconomic institutions.     

Forecasting the diffusion of photovoltaic systems in southern Europe : A learning curve approach

Most analysts disagree upon whether photovoltaic systems (PV) will be able to play an important role in the energy scenarios of the future. A few scholars also question the appropriateness of policies that envisage the use of public subsidies to stimulate the growth of this industry and to accelerate market penetration. This paper contributes to this debate by examining whether carefully designed policies may initiate a process of large-scale diffusion of grid-connected PV, even without the deployment of external subsidies. Building upon a disaggregated characterization of the electricity market, it takes endogenously into account the learning curve phenomenon and simulates the diffusion of PV building-integrated systems in five European countries. The analysis is restricted to crystalline silicon systems and is repeated under four different macroeconomic scenarios corresponding to four different energy policies. The results suggest that already today there are opportunities for PV diffusion in many islands of the Mediterranean region, which may trigger sufficient scale economies to render the technology competitive in larger markets. They also show that the diffusion process could be accelerated through the implementation of carbon-tax policies that support initial penetration. The environmental benefits (net avoided CO₂ emissions over the system life cycle) associated with the forecasted penetration are also evaluated.     

基于顾客需求的物流地产价值创新

借助对物流地产与商业地产、工业地产的比较分析,探讨了物流地产的内涵,对普洛斯的物流地产运作模式进行了案例分析,并对其物流地产的价值创新战略进行了阐释。     

通过加总推出的总供给曲线

总供给曲线的推导是宏观经济学中的最重要内容之一。在大多数宏观经济模型中 ,在推导总供给曲线时 ,加总问题 (aggregationproblem)往往被忽略。一般认为 ,总供给曲线是各企业供给曲线的简单算术和或是一个代表性企业供给曲线的简单放大。但是 ,在现实中 ,各个企业是不同的。只有在非常严格的条件下 ,总供给曲线与企业供给曲线在性质上才是等价的。考虑到中国经济的制度性特点并在解决加总的一系列技术问题的基础上 ,本文推导出了在企业劳动生产率服从均匀分布情况下的总供给曲线。通过这种方法推出的总供给曲线具有许多传统总供给曲线所不具有的新性质。笔者希望本文能为进一步研究处于微观经济和宏观经济之间的往往被忽视的一块重要领域 (“中观经济领域”)做出贡献。     

商业银行利率风险计量模型及实证分析--非平移收益曲线条件下的随机免疫策略

传统的久期理论建立在收益曲线平移等严格假设条件上，因而其在实践中的有效性大大降低了。根据Markowitz（1959）等理论可推导出：资产价格的总风险包括收益的方差和全久期向量两部分；假若商业银行采取现金中性（cash neutrality）的资产交易策略，风险计量模型可转换为线性规划问题，从而可以构建基于利率风险最小化模型的随机免疫策略。也就是说，引入随机免疫的理念来替代经典的免疫理论，通过实证分析得出：无现金交易条件下的随机免疫策略能够降低利率风险。     

The Last Word on the Wage Curve?

Abstract.  Since 1990, there has been extensive international research on the responsiveness of wages of individuals to changing local labour market conditions. For many countries, an inverse relationship between wages and local unemployment rates has been found. In their book, The Wage Curve , Blanchflower and Oswald argued that the unemployment elasticity of pay is around −0.1 in most countries. In a 1995 literature survey, Card referred to this striking empirical regularity as being close to an 'empirical law of economics'. Nonetheless, reported elasticities do vary, even excluding outliers, between about −0.5 and +0.1. There is also considerable heterogeneity among wage curve studies in terms of data and model specification. This paper carries out meta‐analytic techniques on a sample of 208 elasticities derived from the literature to uncover the reasons for the differences in empirical results across studies. Several causes of variation are identified. There is also clear evidence of downward publication bias. In addition, many reported t ‐statistics are biased upwards due to the use of aggregate unemployment rates. A maximum likelihood method and a trimming procedure are used to correct for these biases. Both methods give similar results for our sample. An unbiased estimate of the wage curve elasticity at the means of study characteristics is about −0.07.     

Technological change in energy systems: Learning curves, logistic curves and input-output coefficients

Learning curves have recently been widely adopted in climate-economy models to incorporate endogenous change of energy technologies, replacing the conventional assumption of an autonomous energy efficiency improvement. However, there has been little consideration of the credibility of the learning curve. The current trend that many important energy and climate change policy analyses rely on the learning curve means that it is of great importance to critically examine the basis for learning curves. Here, we analyse the use of learning curves in energy technology, usually implemented as a simple power function. We find that the learning curve cannot separate the effects of price and technological change, cannot reflect continuous and qualitative change of both conventional and emerging energy technologies, cannot help to determine the time paths of technological investment, and misses the central role of R&D activity in driving technological change. We argue that a logistic curve of improving performance modified to include R&D activity as a driving variable can better describe the cost reductions in energy technologies. Furthermore, we demonstrate that the top-down Leontief technology can incorporate the bottom-up technologies that improve along either the learning curve or the logistic curve, through changing input-output coefficients. An application to UK wind power illustrates that the logistic curve fits the observed data better and implies greater potential for cost reduction than the learning curve does.     

Some properties of the length of the shortest half

This paper discusses some properties of the length of the shortest half proposed by Rousseeuw and Leroy (1988) as a robust scale estimator.