On Non-Nash Equilibria

I consider generalisations of the Nash equilibrium concept based on the idea that in equilibrium the players' beliefs should not be contradicted, even if they could possibly be incorrect. This possibility depends on the information about opponents' behaviour available to the players in equilibrium. Therefore the players' information is crucial for this notion of equilibrium, called Conjectural Equilibrium in general and Rationalizable Conjectural Equilibrium (Rubinstein-Wolinsky 1994) when the game and the players' Bayesian rationality are common knowledge. In this paper I argue for a refinement of Rationalizable Conjectural Equilibrium showing by propositions and by examples how this equilibrium notion works and how the suitable equilibrium concept depends on the players' information.Journal of Economic LiteratureClassification Numbers: C72, D83, D82.     

Equilibrium with Default and Endogenous Collateral

We study a two‐period general equilibrium model with incomplete asset markets and default. We make collateral endogenous by allowing each seller of assets to fix the level of collateral. Sellers are required to provide collateral whose first‐period value, per unit of asset, exceeds the asset price by an arbitrarily small amount. Moreover, borrowers are also required to be fully covered by the purchase, in the first period, of state‐by‐state default insurance. These insurance contracts are offered by lenders. The insurance cost or revenue is a linear charge and plays the role of a spread penalizing borrowers who will incur in default and benefiting lenders who will suffer default. Under these assumptions, equilibrium always exists.     

What Enhances Insider Trading Profitability?

This study analyses the factors triggering insider trading profitability. Since there is not much evidence on this topic in the continental-European context, we focus on the Spanish stock market. Our findings show that the main relevant factors (the timing ability of the insider, the transparency of the transaction and the level of free cash flow of the firm) are related to insiders’ opportunities behaviour, motivated by the lack of either managerial control within the firm or enforcement of insider trading regulation. The level of ownership concentration, the spread and the interaction between the size and the transparency of the transaction are other relevant factors, some of them tested for the first time in the insider trading literature.      

Pushing on a String: How policy might encourage private doctors to compete with the public sector on the basis of quality

Results from the Philippine Quality Improvement Demonstration Study show that a policy that expands insurance coverage improves quality of care, as measured by clinical performance vignettes, among public physicians, and induces a spillover effect that improves quality among private physicians.     

An optimization approach to strategic sourcing: A case study of the United States Air Force

The DoD annually procures billions of dollars worth of systems, supplies, and services in support of the national military strategy. Faced with budget cuts and other resource constraints, the DoD must transform its procurement process to ensure cost-effective sourcing of critical supplies and services. One aspect of current transformation in the DoD is the use of a strategic sourcing approach for the procurement of services at military installations. Using the Air Force's strategic sourcing process as our context, we developed an optimization model for selecting a set of proposals from among multiple offerors for services to be performed at multiple installations. The selection achieves the most favorable objective by balancing the confidence level in an offeror's past performance with the cost of services to the Air Force. The research findings, which are based on a realistic scenario, demonstrate improvements over the current sourcing process in both overall performance and cost.     

L’EFFICIENCE DES COOPERATIVES DE SERVICES FINANCIERS: UNE ANALYSE DE LA CONTRIBUTION DU MILIEU*

RÉSUMÉ 1 : Le faible niveau moyen d’efficience des institutions bancaires habituellement trouvé dans les études empiriques a été qualifié de « boîte noire » par Berger et Mester (1997) . Cette étude cherche à identifier si les caractéristiques de l’environnement de même que celles qui sont propres à une coopérative d’épargne et de crédit pourraient expliquer une partie des écarts de performance apparaissant dans les scores d’efficience. Le modèle de coût que nous avons estimé est basé sur la valeur ajoutée par l’intermédiation financière. Par ailleurs, pour éviter la perte d’informations découlant de la borne à l’unité des scores d’efficience découlant du DEA, nous avons comparé les résultats d’une analyse avec le score d’efficience et de superefficience. Nos résultats montrent qu’au moins 34% des écarts de scores peuvent être expliqués par un ensemble limité de variables: taille de la coopérative, taux de capitalisation, épargne par membre, nombre de membres et type de marché.     

Controlling the Urban Fabric: The Complex Game of Distance and Proximity in European Upper‐Middle‐Class Residential Strategies

This article presents an open discussion of the processes of urban secession and gentrification in contemporary European cities, arguing that intergroup social dynamics in urban spaces are generally more complex than either extreme mutual avoidance or the colonization of neighbourhoods by the wealthiest groups. We analyse the residential strategies of urban upper‐middle class managers in various European metropolitan areas through in‐depth semi‐structured interviews to argue that these groups develop complex strategies of proximity and distance in relation to other social groups. The development of these ‘partial exit’ strategies takes place through specific combinations of practices that allow groups to select the dimensions they are willing to share with other social groups, and those in which they prefer a more segregated social environment for themselves and their families. The responses of our interviewees were consistently more nuanced and complex than suggested by a simplistic theory about their drive to withdraw from society, forcing us to develop more sophisticated conceptual frameworks to account for the growing prevalence of multi‐layered identities and spheres of reference and solidarity, specific combinations of elective segregation and local involvement, and more active patterns of mobility combined with local embeddedness.