Voting in small networks with cross-pressure

We present a model of participation in elections in small networks, in which citizens suffer from cross-pressures if voting against the alternative preferred by some of their social contacts. We analyze how the existence of cross-pressures may shape voting decisions, and so, political outcomes; and how parties may exploit this effect to their interest. We characterize the strong perfect equilibria of the game and show that, in equilibrium, the social network determines which party wins the election. We also show that to dispose of the citizens better connected in the network with the other faction is not a guarantee to win the election.      

Fair allocation in networks with externalities

I prove existence and uniqueness of a component efficient and fair allocation rule when the value of the network is allowed to exhibit any type of externalities across its components. This is done by means of a new specification of the value function, generalizing partial results appearing in Myerson [Myerson, R.B., 1977a. Graphs and cooperation in games. Math. Operations Res. 2, 225–229], Feldman [Feldman, B.E., 1996. Bargaining, coalition formation and value. PhD dissertation. State University of New York at Stony Brook] and Jackson and Wolinsky [Jackson, M.O., Wolinsky, A., 1996. A strategic model of social and economic networks. J. Econ. Theory 71, 44–74]. This component efficient and fair allocation rule is found closely related to an extension of the Shapley value to TU-games in partition function form proposed by Myerson [Myerson, R.B., 1977b. Values of games in partition function form. Int. J. Game Theory 6 (1), 23–31].     

Competition in telecommunication networks with call externalities

This paper describes a model involving two interconnected networks offering different degrees of quality. In these networks, there are call externalities enabling consumers to assess the quality of the calls they send and receive. Networks compete in two-part tariffs. Our aim is to show that the “profit neutrality” result no longer applies due to network asymmetry and call externalities. In the case of non reciprocal access charges, call externalities generate private incentives enabling each competitor to charge low access prices. This reduces the risk of tacit collusion as competitors are free to negotiate their access charges.      

我国贸易条件异常波动的内外冲击因素

针对2007年第二季度至2012年期间我国价格贸易条件异常波动的现象,文章利用可变参数状态空间模型,比较分析了相关要素的影响方向和力度。结果表明:(1)国外产出缺口、国际大宗商品价格和人民币升值是影响我国价格贸易条件异常波动的主要原因;(2)比较收入贸易条件的影响因素,国外产出缺口始终处于正向影响,人民币升值具有较强的负向影响,国际大宗商品价格和国内通货膨胀的影响较中性。     

中国股市机构投资者多账户交易行为研究

多账户交易行为是中国机构投资者的典型特征,是中国股票市场的特有现象。限于交易数据的可获得性,相关研究较少。本文提出了一种从交易数据中将机构投资者的交易记录分离出来的方法。据此,本文分析了机构投资者证券账户与资金账户的对应关系,证实了多账户交易行为的存在,发现采用多账户交易的机构投资者具有集中投资、日内多次交易、利用不同证券账户进行建仓、对敲、拉升股价、出货等基本特征。根据实证研究的结果并结合实例,本文揭示了机构投资者多账户交易的动机是隐蔽交易、拉升股价和申购新股。     

How bad is forming your own opinion?

The question of how people form their opinion has fascinated economists and sociologists for long time. In many of the models, a group of people in a social network, each holding a numerical opinion, arrive at a shared opinion through repeated averaging with their neighbors in the network. Motivated by the observation that in reality consensus is rarely reached, we study a related sociological model in which individuals' intrinsic beliefs counterbalance the averaging process and yield a diversity of opinions.We interpret the repeated averaging process as best-response dynamics in an underlying game with natural payoffs and its limit as an equilibrium. This allows us to study the cost of disagreement by comparing between the cost at equilibrium and the social optimum. We also consider a natural network design problem in this setting: which links can we add to the underlying network to reduce the cost at equilibrium?     

Farsightedly stable networks

A set of networks G is pairwise farsightedly stable (i) if all possible farsighted pairwise deviations from any network g G to a network outside G are deterred by the threat of ending worse off or equally well off, (ii) if there exists a farsighted improving path from any network outside the set leading to some network in the set, and (iii) if there is no proper subset of G satisfying conditions (i) and (ii). A non-empty pairwise farsightedly stable set always exists. We provide a full characterization of unique pairwise farsightedly stable sets of networks. Contrary to other pairwise concepts, pairwise farsighted stability yields a Pareto dominant network, if it exists, as the unique outcome. Finally, we study the relationship between pairwise farsighted stability and other concepts such as the largest pairwise consistent set and the von Neumann–Morgenstern pairwise farsightedly stable set.     

Bayesian learning in social networks

We extend the standard model of social learning in two ways. First, we introduce a social network and assume that agents can only observe the actions of agents to whom they are connected by this network. Secondly, we allow agents to choose a different action at each date. If the network satisfies a connectedness assumption, the initial diversity resulting from diverse private information is eventually replaced by uniformity of actions, though not necessarily of beliefs, in finite time with probability one. We look at particular networks to illustrate the impact of network architecture on speed of convergence and the optimality of absorbing states. Convergence is remarkably rapid, so that asymptotic results are a good approximation even in the medium run.     

Returns from social capital in open source software networks

Open Source Software projects base their operation on a collaborative structure for knowledge exchange in the form of provision or reception of information, expertise and feedback on the creation of source code. Here, we address the direction of these knowledge flows among projects throughout social networks and their impact on project success. We identify the roles of membership or contribution that individuals play within projects. We found that connections through contributors who bring their knowledge to the project, improve project success, and that connection through members, who transfer their knowledge towards other projects, enhance project success. Finally, we found that ties through shared membership and contributions hamper project success. The analysis of knowledge flows and their impact on project success imply a translation of returns from investment in social capital, where investment takes the shape of knowledge flows and the returns mean the projects’ diffusion over the network.

俄罗斯金融市场套利交易的形成、影响及启示

20世纪90年代以来,俄罗斯在高度开放和自由的经济环境下,开展金融自由化改革,由此导致大量资本通过外债形式进入俄罗斯金融市场进行套利交易,套利资本推动俄罗斯经济、金融业的发展。而当套利资本迅速撤离俄罗斯市场时,俄罗斯金融市场就出现了银行业流动性吃紧、大规模抛售卢布现象,俄罗斯经济受到重创,最为典型的是1998年和2008年俄罗斯爆发的金融危机。文章试图通过研究俄罗斯的套利交易形成的影响因素,深刻理解俄罗斯金融危机。近年来,人民币不断升值,人民币跨境清算范围不断扩大,中国也面临着"热钱"监管压力,研究俄罗斯套利交易,对中国具有重要的借鉴意义。     

社会结构影响下房价测度模型研究

笔者以美国房价为样本,选取了可能影响房价的13个因素,以特征价格法的思想为基础,运用回归分析、聚类分析、神经网络模型、回归树模型等统计工具,构造房价关于特征因素的测度模型,探究房价的关键作用因素。笔者通过分析得出,room(房间数)和lsat(低层阶级人口比例的对数)是两个最重要的变量,它的政策含义是,国家应该大力增加房产信息透明性,并在房地产政策调整过程中注意阶层差异化的影响。     

A two-country dynamic Heckscher–Ohlin model with physical and human capital accumulation

We study a two-country endogenous growth model in which the long-run growth is propelled by the accumulation of physical and human capital. We show that in the integrated world economy, there exists a unique and locally saddlepoint stable balanced growth equilibrium. We also show that the incorporation of adjustment costs in the process of human capital accumulation leads to a lower long-run growth rate. We then show that, in the 2-country world economy with international trade, balanced growth is possible. Finally, we present a dynamic Heckscher–Ohlin theorem concerning the pattern of international trade. We appreciate the constructive comments from an anonymous referee which have improved this paper significantly. We acknowledge also with gratitude the valuable comments of Hideyuki Adachi, Kosuke Aoki, Daniel Bernhofen, Eric Bond, Koichi Futagami, Ronald Jones, Tamotsu Nakamura and Raymond Riezman on earlier versions. We appreciate also the beneficial comments from the participants of the GEP conference on New Directions in International Trade Theory held in the University of Nottingham and of the Adachi OB Workshop in Kobe University.     

试析我国贸易余额波动的成因

本文对HoffmaisterandRold幃ｓ( 1 999,2 0 0 1 )与Prasad ( 1 999)两文中的模型进行了扩展 ,构造了一个结构向量自回归模型 (SVAR) ,用以探讨在 1 985— 2 0 0 0年间影响中国贸易余额的因素。文章分析了国外供给冲击、国内供给冲击、相对需求冲击及名义冲击等四类因素对贸易余额的影响 ,并注意区分了结构性和短期性因素。研究结果表明 :实际冲击 ① 是影响中国贸易余额的主要因素 ;人民币汇率存在一定程度的低估 ,但汇率变动对贸易余额影响不大。因此 ,货币性手段将不足以解决所谓的中国“贸易失衡”问题。     

One-way flow networks: the role of heterogeneity

I study a one-way flow connections model in which players are heterogeneous with respect to values and the costs of establishing a link. I show that values and costs heterogeneity are equally important in determining the level of connectedness and the architecture of equilibrium networks. I also show that when asymmetries are independent of the potential partner there are distributions of costs and values for which centrality is a distincitive feature of equilibrium networks. This sharply contrasts with the homogeneous case.I thank an anonymous referee for useful comments. The paper has benefited from discussion with Gabriella Conti, Jose Luis Moraga-Gonzalez, Fernando Vega-Redondo and Sanjeev Goyal.     

Regional social capital: Embeddedness, innovation networks and regional economic development

Technology is a necessary but not a sufficient condition for regional economic development. Regional innovation networks transform technology into competitiveness of firms and thus contribute to economic development. Intangible assets, such as social capital, decide how effective regional innovation networks function. Differences in regional social capital thus help explain regional differences in economic development. Regional social capital originates from the embeddedness of firms in regional webs of social relations. The norms, values and customs of these networks facilitate collaboration for mutual benefit. As innovation is increasingly a network effort, embeddedness and social capital also help explain how and why networks of innovating companies are successful, as the case study of the Stimulus Cluster Scheme shows.     

Existence of Nash networks in one-way flow models

This paper addresses the existence of Nash equilibria in one-way flow models in a number of different settings. In these models players form costly links with other players and obtain resources from them through the directed path connecting them. We find that heterogeneity in the costs of establishing links plays a crucial role for the existence of Nash networks. The paper also provides conditions for the existence of Nash networks in models where costs and values of links are heterogeneous. We would like to thank an anonymous referee for useful suggestions. We would also like to thank Hans Haller and participants at the AEA Meetings 2007 for helpful comments. Sudipta Sarangi acknowledges the support of NSF grant HSD-0527315 and the hospitality of CREUSET, Jean Monnet University.     

国际农产品价格如何影响了中国农产品价格?

本文使用月度数据考察国际农产品价格是否影响中国农产品价格,以及影响程度和可能的影响机制。在控制了其他影响因素的条件下,本文证实了国际农产品价格对国内价格具有经济意义上的显著影响,各种农产品的国内价格对相同产品国际价格的反应程度存在较大差异,玉米、大米和大豆价格的国际价格弹性介于0.20到0.36之间,小麦的国际价格弹性为0.05左右,国内外农产品市场间高度的整合关系主要是通过国际贸易建立的。中国在未来为保持粮价稳定需要加大对农业的扶持力度,加强国内农产品储备,合理地对农产品贸易进行管制,建立农产品价格预警机制,并通过财政补贴等手段平抑因国际价格波动而带来的国内农产品价格上涨。