Similarity of differential information with subjective prior beliefs

We present a complete, separable and metrizable topology on the product space of information and (subjective) beliefs. Such a topology formalizes similarity of differential information without the assumption of a common prior, but under the assumption that objectively impossible events are considered impossible by subjective beliefs. As an application to the theory of the consumer, we provide results on the continuity of expected utility and demand functions. We also provide continuity results for the value of information and the insurance premium as defined in the literature.     

Local minimax pointwise estimation of a multivariate density

We consider the problem of the nonparametric minimax estimation of a multivariate density at a given point. A concept of smoothness classes in nonparametric minimax estimation problems is proposed. The smoothness of a function is characterized by the approximability of the function at a point by an integral of the product of this function with an approximate identity. We propose a singular integral estimator, an integral of this approximate identity with respect to the empirical distribution function. Under some assumptions on the approximate identity, the bias of the estimator is shown to be of smaller order asymptotically than the variance, and the estimator itself is shown to be asymptotically locally minimax with respect to the quadratic risk in a proper topology.     

The topology of information on the space of probability measures over Polish spaces

We study here the topology of information on the space of probability measures over Polish spaces that was defined in Hellwig (1996). We show that under this topology, a convergent sequence of probability measures satisfying a conditional independence property converges to a measure that also satisfies the same conditional independence property. This also corrects the proof of a claim in Hellwig (1996, Lemma 4). Additionally, we determine sufficient conditions on the Polish spaces and the topology over measure spaces under which a convergent sequence of probability measures is also convergent in the topology of information.     

Analysis of Internet topology with a three‐level components model

The vertical structure of the Internet is considered as having three‐level components: backhyphen‐bone‐level interconnection, mid‐level transit, and local‐level access. This paper considers single and cross mergers between an integrated provider and an entrant in the different area. As a result of these mergers, cross entry, in which both integrated providers merge with the retail entrants in the other areas, is more socially desirable than single entry, in which only one firm merges, which is, in turn, preferred to no entry. Copyright © 2005 John Wiley & Sons, Ltd.     

Hysteresis versus NAIRU and convergence versus divergence: The behavior of regional unemployment rates in Brazil

The aim of this work is to analyze the regional unemployment rate behavior in Brazil. Firstly, unit root tests with structural breaks were used to determine which theoretical framework – hysteresis or NAIRU – is more appropriate to explain the unemployment dynamics not only in six Brazilian metropolitan areas – São Paulo, Rio de Janeiro, Belo Horizonte, Porto Alegre, Salvador and Recife – but also at national level. Hysteresis is found to be the best choice in five, but Rio de Janeiro. This indicates a high persistence in the Brazilian regional unemployment rate. Secondly, we investigated whether these five metropolitan regions, characterized by the hysteresis effect, show a stochastic convergence. The latter was found in every case, but Porto Alegre.     

Interpolation and backdating with a large information set

Existing methods for data interpolation or backdating are either univariate or based on a very limited number of series, due to data and computing constraints that were binding until the recent past. Nowadays large datasets are readily available, and models with hundreds of parameters are easily estimated. We model these large datasets with a factor model, and develop an interpolation method that exploits the estimated factors as an efficient summary of all available information. The method is compared with existing standard approaches from a theoretical point of view, by means of Monte Carlo simulations, and also when applied to actual macroeconomic series. The results indicate that our method is rather robust to model misspecification, although traditional multivariate methods also work well while univariate approaches are systematically outperformed. When interpolated series are subsequently used in econometric analyses, biases can emerge, but they are smaller with multivariate approaches, including factor-based ones.     

Precautionary behavior and consumer information: A Markov process approach

This paper explores the role of consumer confidence in the equilibrium of a dynamic macroeconomic growth model with rational expectations. Consumers face an uncertain future income stream due to a Markov stochastic process that affects production. Changes in the properties of this process change consumer information sets and optimal policies in the rational expectations format. Increases in “persistence” in the shock process are considered; this is identified with the consumer's subjective assessment of future economic conditions. Two cases are considered: where either good or bad states of the process are more likely to persist into the future, and where bad states persist unconditionally at the expense of good. Consistent with earlier treatments of savings under uncertainty (Barsky, Mankiw and Zeldes 1986, and Skinner 1988), the consumer's response to increased income uncertainty is to exhibit precautionary saving behavior. The infinite-horizon growth model format used offers significant improvement over other finite-horizon life cycle models. Specifically, the model is a full general equilibrium model and the solutions are rational expectations solutions. The technique also is easily adapted to other recursive decision problems under uncertainty.     

论地方政府行为效用导致的区域产业政策趋同

在区域经济的发展过程中,地方政府之间日益激烈的竞争必然会造成区域之间的产业政策趋同。这对于区域经济的协调发展和长远发展极为不利。应当通过提高中央政府的宏观调控水平,强化地方政府的责、权、利边界,引导地方政府在区域产业政策中体现差异性。     

Introduction to designing information and organizations with a positive lens

The role and potential contribution of a positive lens to the design of systems and organizations is the focus of this introductory essay. The positive lens refers to a perspective in the social sciences that emphasizes the capacity of people and organizations to construct better work environments, customer experiences and socio-technical systems through a positive discourse. Joining a positive lens on organizing with the transformative power of design thinking opens new horizons and uncovers previously overlooked possibilities for creating organizational and social well-being. This volume aims to introduce design with a positive lens into the research on information systems and organizations and to explore its potential value.     

Artificial stock markets with different maturity levels: simulation of information asymmetry and herd behavior using agent-based and network models

This paper aims mainly at building artificial stock markets with different maturity levels by modeling information asymmetry and herd behavior. The developed artificial markets are multi-assets, order-driven and populated by agents having heterogeneous behaviors and information. Agents are defined by their information and their herd behavior levels. Agents trade multiple risky assets based on their wealth, their behaviors and their available information which spread among multiple behavioral networks. In a novel contribution to artificial stock markets literature, agents’ behaviors modeling is mixed with social network simulation to reproduce different degrees of information asymmetry and herd behavior based on several assortative topologies. Several simulations validated the proposed model since univariate and multivariate stylized facts were reproduced both for mature and immature stock markets. The proposed artificial stock market can be considered as a first step toward decision and simulation tools for optimal management, strategy analysis and predictions evolution of immature stock markets.     

Efficiency and information aggregation in auctions with costly information

Consider an auction in which k identical objects are sold to n > k bidders who each have a value for one object which can have both private and common components to it. Private information concerning the common component of the object is not exogenously given, but rather endogenous and bidders face a cost to becoming informed. If the cost of information is not prohibitively high, then the equilibrium price in a uniform price auction will not aggregate private information, in contrast to the costless information case. Moreover, for a wide class of auctions if the cost of information is not prohibitively high then the objects can only be allocated in a weakly efficient sense, and then only if the equilibrium proportion of endogenously informed agents is vanishing as the economy grows. In spite of these results, it is shown that there is a mechanism for which there exist equilibria and for which (weak) efficiency is achieved as the economy grows in the face of endogenous information acquisition.Received: 6 August 2001, Accepted: 27 July 2002, JEL Classification: C72, D44, D82Financial support under NSF grant SBR-9507912 is gratefully acknowledged. I thank Valentina Bali for conversations out of which this project grew, and Larry Ausubel for a very helpful discussion of an early version of this paper at the 1998 summer meetings of the Econometric Society from which I have borrowed in structuring the exposition of the paper. I also thank Andy Postlewaite, Jeroen Swinkels, and an associate editor and anonymous referee for helpful comments and suggestions on earlier drafts.     

融合新闻要素的跨语言新闻文本相似度计算

随着经济全球化程度的加深,我国与各国之间的交流、合作越来越频繁,各类大小事件的新闻报道各国各有侧重,新闻内容的匹配程度也有高低之分。传统的文本相似度方法具有计算维数过高和计算过于复杂的缺点。通过对新闻报道文本的分析发现,新闻报道具有何时、何地、何事、何因、何人五个基本因素的特点。针对这一特性,提出融合新闻要素的跨语言新闻文本相似度计算方法。该方法充分考虑到了新闻文本的五个新闻要素特征词对文本相似度的影响,有效减少了相似度低的文本干扰和传统文本相似度计算效率的问题。本文方法抽取新闻文本的新闻要素,借助翻译工具和词义消歧技术将抽取出来的不同语种的新闻要素统一为中文,并对新闻要素进行分类集合,然后利用集合相似度计算和数据融合方法来计算两篇新闻文本相似度,通过实验验证,本文方法对跨语言新闻文本相似度计算具有一定的效率和准确性,说明本文方法可行。     

Growth and convergence in a multi-country empirical stochastic Solow model

The paper considers international per capita output and its growth using a panel of data for 102 countries between 1960 and 1989. It sets out an explicitly stochastic Solow growth model and shows that this has quite different properties from the standard approach where the output equation is obtained by adding an error term to the linearized solution of a deterministic Solow model. It examines the econometric properties of estimates of beta convergence as traditionally defined in the literature and shows that all these estimates are subject to substantial biases. Our empirical estimates clearly reflect the nature and the magnitude of these biases as predicted by econometric theory. Steady state growth rates differ significantly across countries and once this heterogeneity is allowed for the estimates of beta are substantially higher than the consensus in the literature. But they are very imprecisely estimated and difficult to interpret. The paper also discusses the economic implications of these results for sigma convergence. © 1997 John Wiley & Sons, Ltd.     

Nash-equilibria in a heterogeneous oligopoly with fuzzy information

We consider a model of an oligopolistic market with heterogeneous firms and products where neither the cost nor the demand functions are common knowledge. Instead, each firm only has some vague ideas about the price strategies adopted by its competitors which is modelled by a fuzzy set. In analogy to the notion of an "equilibrium of actions and beliefs" we define and characterize a generalized Nash-equilibrium and show its existence under general conditions. Furthermore, the impact of the fuzzy information on the equilibrium outcome is analyzed by means of a comparative static analysis within a particular model framework.Received: 28 May 2002, Accepted: 25 December 2002, JEL Classification: D43, D80, L13We wish to thank Bernhard F. Arnold, the editor Murat Sertel , and two anonymous referees for helpful comments. Of course, we are responsible for all remaining errors.     

Efficient minimum distance estimation with multiple rates of convergence

This paper extends the asymptotic theory of GMM inference to allow sample counterparts of the estimating equations to converge at (multiple) rates, different from the usual square-root of the sample size. In this setting, we provide consistent estimation of the structural parameters. In addition, we define a convenient rotation in the parameter space (or reparametrization) to disentangle the different rates of convergence. More precisely, we identify special linear combinations of the structural parameters associated with a specific rate of convergence. Finally, we demonstrate the validity of usual inference procedures, like the overidentification test and Wald test, with standard formulas. It is important to stress that both estimation and testing work without requiring the knowledge of the various rates. However, the assessment of these rates is crucial for (asymptotic) power considerations.Possible applications include econometric problems with two dimensions of asymptotics, due to trimming, tail estimation, infill asymptotic, social interactions, kernel smoothing or any kind of regularization.     

Country and industry convergence of equity markets: International evidence from club convergence and clustering

This study employs the panel convergence methodology developed by Phillips and Sul (2007) to explore the convergence dynamics of international equity markets. The analysis considers both country and industry effects. While traditional portfolio management strategies usually follow a top-down procedure, assuming that country-level effects drive financial aggregates (e.g., stock returns) our empirical results suggest that the equity markets of 37 of the 42 counties in our sample do form a unified convergence club. The empirical findings, however, also show more numerous stock-price convergence clubs in certain industries. That is, country factors play a more important role in explaining the actual convergence in real stock prices than industry factors. Conversely, the volatility of stock prices exhibits much more evidence of convergence than stock prices. These findings should assist portfolio managers in the design and implementation of appropriate portfolio management strategies. Regulatory authorities also can benefit in the design of financial regulation.     

Transforming industrial relations in Russia: a case of convergence with industrialised market economies?

Here the authors discuss the ‘old unions’, the ‘new unions’ and the still dominant role of the state. They show how contemporary IR includes changes towards arrangements that are more typical of industrialised market economies (IMEs); nevertheless, there are significant continuities with past patterns, and divergences from IMEs’ arrangements.     

Productivity, convergence and policy: a study of OECD countries and industries

This paper analyses trends in labour productivity and its underlying determinants in a panel of OECD countries from 1979 to 2002. Data Envelopment Analysis (DEA) is used to estimate a Malmquist measure of multifactor productivity (MFP) change. We decompose the growth in labour productivity into (i) net technological change (ii) input biased technical change (IBTC) (iii) efficiency change and (iv) capital accumulation. We analyse the effect of each of these factors in the transition towards the equilibrium growth paths of both labour productivity and per capita GDP for the OECD countries, controlling for the effects of different policies and institutions. The results indicate that on average gaps in productivity or income levels are narrowing down although there is no evidence to suggest that the entire OECD area comprises a single convergence “club”. Using kernel estimation methods we find that that labour productivity and per capita GDP are settling toward a twin peak (bimodal) distribution. Panel unit root tests over an extended (1960–2001) period provide general support for the convergence hypothesis. Analysis of the contributions of productivity growth within industries and sectoral composition changes show that aggregate productivity change is predominantly driven by ‘net’ within sector effects with very little contribution emerging from sectoral shifts (the ‘in-between’ static or dynamic effects resulting from higher or above average productivity industries gaining employment shares or low productivity industries losing shares).