Efficient markets and Bayes’ rule

Summary. A series of financial anomalies motivated the development of new theories that modify the rational expectations ideal. Two possibilities have been systematically explored. The literature on behavioral finance relaxes the assumption that agents form beliefs according to the laws of probability and assume, instead, that simpler heuristic rules are used. Another stream of the literature assumes that agents process information according to Bayes rule, but do not posses sufficient information to know the true data generating process. In this paper, Bayesian and Behavioral agents coexist and trade in a standard dynamic asset pricing model. A long-standing conjecture is demonstrated. It is shown that, under suitable assumptions, Bayesian agents drive Behavioral, non-Bayesian agents out of the market. Hence, asset prices are eventually determined under the Bayesian paradigm.Received: 3 June 2004, Revised: 17 September 2004, JEL Classification Numbers: D83.Preliminary versions have circulated under the titles Markets Favor Bayesian Models and Market Selection of Empirical Models under Limited Information. I thank Larry Blume, David Easley, Larry Epstein, Armando Gomes, Bruce Hansen, Lars Hansen, Richard Kihlstrom, Grace Koo, George Mailath, Werner Ploberger, Andrew Postlewaite and Shakeeb Khan for useful comments. I also thank participants at the NBER GE meetings, Evolutionary Finance conference in Zurich, Latin American Meetings of the Econometric Society, Stanford Institute for Theoretical Economics, the Instituto de Matematica Pura e Aplicada, the theory seminar at Brown, Chicago, Harvard-MIT, Minnesota, Penn and Wisconsin. I gratefully acknowledge the financial support from the National Science Foundation Grant SES 0109650.     

略论产业集群技术标准与集聚的正负效应之相关性

产业集群是现代产业发展过程中形成的一种具有典型特征的，介于企业和行业之间的产业组织形态。产业集聚的巨大正效应是产业集群形成和发展的重要原因。同时，产业集聚也会产生负效应，这些负效应可能导致产业集群发展缓慢，甚至衰退和消亡。找到正确有效的途径强化产业集聚的正效应，预防和消除产业集聚的负效应，是保持产业集群健康、持续发展的关键。技术标准对产业和企业的命运起着越来越重要的作用，技术标准与产业集群发展、运行秩序规范、负效应的防范与消除等方面都有着紧密的相关性，是促进产业集群发展的有效工具和手段。     

Industrial revolution and mortality revolution: Two of a kind?

In little more than a century life expectancy has doubled in most parts of the world. Neither facts nor theory support the view that this Mortality Revolution is due to the Industrial Revolution and the era of rapid economic growth that ensued. Rather, both revolutions mark the onset of accelerated and sustained technological change in their respective areas. They occur largely independently of each other, the later occurrence of the Mortality Revolution being due to the later development of biomedical vis-a-vis physical knowledge. Comparative study of the two should prove fruitful. Although entrepreneurship is important in each, there appear to be differences in the underlying motivations and the role of private property and other institutions. Links between technological change, on the one hand, and scale of operation, capital inputs, and education, on the other, also offer promising possibilities for comparative study.The author is grateful to Donna Hokoda Ebata and Christine M. Schaeffer for excellent assistance, the University of Southern California for financial support, and to Eileen M. Crimmins, Samuel H. Preston, Morton O. Schapiro, Roger S. Schofield, and two referees for helpful comments.     

上市公司资产减值方向信息含量研究——来自沪深两市2003年的经验证据

我国新颁布的《企业会计准则第8号——资产减值》规定,存货等已确认的资产减值不得转回。针对新准则对资产减值单向计提的规定,本文从资产减值准备计提方向研究上市公司资产减值的信息含量,发现资产减值的计提方向存在信号显示作用。这表明资产减值准备方向传递了公司未来前景的信息,全面取缔资产减值准备的转回将减少资产减值的部分信息含量。     

Economic progress and skill obsolescence with network effects

Summary. We construct an OLG model with network effects to examine skill obsolescence when individuals can choose technological vintages. In the absence of transfer payments, some regions of the parameter space have unique stationary equilibria, others have unique cyclical equilibria, and others have multiple stationary equilibria. All equilibria are Pareto efficient. However, rat race equilibria can exist in which all agents currently alive prefer a slower rate of progress than occurs in equilibrium. When contemporaneous transfers are allowed, equilibria are unique everywhere, but a cycle still exists, and a rat race can still arise in equilibrium. Allowing intertemporal transfers (debt) ensures that all equilibria are stationary. In the relevant parameter range, the introduction of debt can eliminate cycles and increase the long-run growth rate. No rat race equilibria exist when debt is allowed.Received: 3 January 2002, Revised: 3 June 2004, JEL Classification Numbers: 041, J24, O33. Correspondence to: Ian P. KingEarly versions of this paper were presented at the West Coast Macro Workshop, the Mid-West Macro Meetings, the Canadian Macroeconomics Study Group Meetings, and the Society for Economic Dynamics Meetings. We would like to thank V. V. Chari, Merwan Engineer, Don Ferguson, John Hillas, John Knowles, Dan Peled, Dan Usher, Linda Welling and Julian Wright for helpful comments. We are especially grateful to an anonymous referee for some very useful and substantive comments.     

中欧贸易与欧盟技术性贸易壁垒

近年来,技术性贸易壁垒(TBT)已成为发达国家实施贸易保护主义更为隐蔽、更为有效的手段.作为中国第三大贸易伙伴的欧盟,其实施的各种TBT措施对中国的出口产品产生了严重的影响.因此,必须建立欧盟技术性贸易壁垒预警机制,时时监控其新动向;坚持"以质取胜"的原则,大搞技术创新和产品创新,以更高的产品质量标准和专利注册超越其贸易壁垒.     

地震勘探仪器技术及其发展

综合地震勘探整体的发展情况，比较细致的论述了地震勘探仪器当前应用的技术现状、基本发展规律、技术关键以及未来仪器技术的发展方向。     

A note on the projection properties of Hadamard matrices obtained by the first Payley construction

We show that the projections on four factors of an arbitrary orthogonal array of strength 2 allow the estimation of main effects and two-factor interactions when all other effects are assumed to be zero, if those projections satisfy the bounds given by Weils theorem. The only exceptions are the Hadamard matrices of orders 16 and 24. A consequence is again the estimability of main effects and two-factor interactions for the projections on four factors of the first Payley construction for arbitrary run size.     

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.     

On the evolutionary edge of altruism: a game-theoretic proof of Hamilton’s rule for a simple case of siblings

We offer a game-theoretic proof of Hamiltons rule for the spread of altruism. For a simple case of siblings, we show that the rule can be derived as the outcome of a one-shot prisoners dilemma game between siblings.JEL Classification: A13, C70, D64Correspondence to: Oded Stark, ZEF, University of Bonn, Walter-Flex-Strasse 3, 53113 Bonn, GermanyWe are indebted to an anonymous referee and to Uwe Cantner for helpful comments and suggestions. Partial financial support from the National Institute on Aging (grant RO1-AG13037) and from the Humboldt Foundation is gratefully acknowledged.