SARS的启示--主编寄语

今年五一节黄金周前,北京和安徽相继出现SARS确诊及疑似个案,政府吸取2003年的惨痛教训,主动通报港、澳及世界卫生组织,媒介做了及时公正的报道,信息透明度远比去年好,控制措施到位.世界卫生组织并没有因为北京、安徽出现SARS病例,对中国发出"旅游警示",一切进行得那么平静和安稳.     

实物期权视角下的跨国企业从华撤资"迟滞"研究——来自日本跨国企业从华撤资的证据

随着中国投资环境的变化,近年来跨国企业从华撤资的现象时有发生;然而,这些撤资却存在"迟滞"现象.文章从实物期权的视角,以日本的跨国企业为样本,利用Cox比例风险模型,对影响跨国企业从华撤资"迟滞"的因素进行了实证检验.研究表明:(1)所在行业的需求不确定性与投资不可逆性影响了日本跨国企业的从华撤资决策,投资不可逆性越高与需求不确定性越大,日本跨国企业从华撤资时越有可能发生"迟滞";(2)跨国企业的投资不可逆性和多元化程度对不确定性影响撤资"迟滞"具有调节作用,投资不可逆性强化了不确定性对撤资"迟滞"的正向影响,而日本跨国企业在华的多元化程度则弱化了这种影响;(3)分支机构的冗余性和灵活性对跨国企业从华撤资"迟滞"都具有正向影响,即日本跨国企业在华分支机构的冗余性和灵活性都提高了分支机构被撤出的风险.文章的研究结论不仅有助于跨国企业理性地对待东道国市场的不确定性,避免盲目地撤出东道国,而且有助于跨国企业选择合理的撤出对象,优化在东道国的分支机构组合.     

Learning from processing trade: Firm evidence from China

Processing export plays a significant role in international trade. In this paper, focusing on firm-level dynamics, we show that firms learn from their processing export experience to improve their subsequent ordinary export outcomes. Using transaction-level trade data and firm-level production data, we show that firms’ ordinary export performance, at both extensive and intensive margins, is enhanced by their own processing experience. Firms also export products with improved quality after engaging in processing exports of similar products. Furthermore, we investigate potential channels through which firms learn from processing experience. We find that firms potentially learn from processing experience to enhance production efficiency, to better understand how to improve product appeal to cater to specific markets, and to gain better and easier access to inputs. Moreover, we find that exporters benefit more from processing experience for larger markets with fiercer competition. Similarly, stronger learning effects are also observed when processing experience is associated with products that embody less diffused knowledge and are more differentiated. Also, firms learn more from processing experience when they are more actively engaged in processing imports. Lastly, we verify the economic significance and quantify the importance of these potential channels.     

Non-convexities and the gains from concealing defenses from committed terrorists

How should countries defend against committed terrorists who attack until defeated? We identify a fundamental non-convexity—one only needs to defeat the terrorist once. Consequently, provided a country values targets similarly, it should conceal defenses and allocate defense resources randomly.     

Learning from Neighbours

When payoffs from different actions are unknown, agents use their own past experience as well as the experience of their neighbours to guide their decision making. In this paper, we develop a general framework to study the relationship between the structure of these neighbourhoods and the process of social learning.
We show that, in a connected society, local learning ensures that all agents obtain the same payoffs in the long run. Thus, if actions have different payoffs, then all agents choose the same action, and social conformism obtains. We develop conditions on the distribution of prior beliefs, the structure of neighbourhoods and the informativeness of actions under which this action is optimal. In particular, we identify a property of neighbourhood structures—local independence—which greatly facilitates social learning. Simulations of the model generate spatial and temporal patterns of adoption that are consistent with empirical work.     

离开威权主义后的演进路径

本文对威权政体进行了新的分类,以此研究政体类型对非民主政体的存续或消亡的影响,以及不同的威权主义政体对民主发展的影响。本文研究结果显示,不同的威权主义政体所面对的民主发展倾向是不同的。因此,威权主义的不同本质应当成为民主的关键前提之一。有限的多党政体是迈向民主体制的主要方式。事实上,这种政体类型已经成为威权主义迈向民主未来的最常见形式：一党体制或军事体制,都有可能先转化为有限的多党政体,再进一步迈向成熟的民主政体。     

Afriat from MaxMin

Afriat’s original method of proof is restored by using the minmax theorem.     

Inferring repeated-game strategies from actions: evidence from trust game experiments

Summary. Combining a strategy model, an inference procedure and a new experimental design, we map sequences of observed actions in repeated games to unobserved strategies that reflect decision-makers’ plans. We demonstrate the method by studying two institutional settings with distinct theoretical predictions. We find that almost all strategies inferred are best responses to one of the inferred strategies of other players, and in one of the settings almost all of the inferred strategies, which include triggers to punish non-cooperators, are consistent with equilibrium strategies. By developing a method to infer unobserved repeated-game strategies from actions, we take a step toward making game theory a more applied tool, bridging a gap between theory and observed behavior.Received: 23 December 2002, Revised: 19 April 2005, JEL Classification Numbers: C72, C80, C90.The authors are indebted for discussions with Ray Battalio, David Cooper, Robin Dubin, John Duffy, Ellen Garbarino, Susan Helper, Margaret Meyer, John Miller, Jim Rebitzer, Mari Rege, Al Roth, and John Van Huyck. The authors also benefited from discussants at economic department seminars at Case Western Reserve, McMaster and McGill University, University of Pittsburgh, SUNY-Stony Brook, and Texas A&M, and participants at the 2002 European Winter Meeting of the Econometric Society. We are grateful for the financial support provided by the Department of Economics at the University of Pittsburgh and Case Western Reserve University.     

Do Urban Neighborhoods Benefit from Homeowners? Evidence from Housing Prices

Homeownership is heavily subsidized in most countries. The adverse effects of this policy on economic efficiency and income distribution are well documented in the economics literature. The main argument in favor of subsidizing homeownership is that it creates positive externalities that offset these adverse effects. In this paper, we test whether homeowners create positive externalities that capitalize into housing prices in multi‐storey buildings. Using semi‐parametric hedonic regressions with and without instrumental variables, we find no evidence of positive externalities, although the results with instrumental variables are somewhat imprecise. This result is robust to several sensitivity checks and to a relaxation of the identification assumptions of our instrument using set identification.     

Intraperitoneal seeding from hepatoma

We report three cases of intraperitoneal seeding from hepatoma. Manifestation of intraperitoneal seeding from hepatoma were intraperitoneal masses (N = 2) and peritoneal thickening (N = 1). Main vascular feeder to intraperitoneal masses was omental branches of the gastroduodenal artery and/or the superior mesenteric artery.     

来自北极冰原的呼唤

在茫茫的北极，渔猎为生的因纽特人在这迷人但严酷的环境中生生不息。凭借对大自然的了解和预测天气的能力，他们成功地生存了下来。他们世世代代生活在这片环境严酷的冰原上，积累了宝贵的气候经验。无论衣食住行，还是文化与生活方式，都与这片冰原环境丝丝相关。现在，这一切正一步步受到威胁。随着全球气候变暖，北极气候开始变得反复无常，难以预测。永久冻土开始解冻，泥石流和海岸侵蚀时常发生。这给因纽特人的生活和生存带来了新的挑战。     

Foreword from the Co-Editors

MOCT-MOST: Economic Policy in Transitional Economies -     

Projecting from current data

The implications of analyzing recent data (rather than historical data) with time as the metric may be philosophically attractive. In the illustration given, these philosophical differences should be considered in determining the integrity of a long-range projection.