49 research outputs found
Privileged information exacerbates market volatility
We study how asymmetric information affects market volatility in a linear setup where the outcome is determined by forecasts about this same outcome. The unique rational expectations equilibrium will be stable when it is the only rationalizable solution. It has been established in the literature that stability is obtained when the sensitivity of the outcome to agents' forecasts is less than 1, provided that this sensitivity is common knowledge. Relaxing this common knowledge assumption, instability is obtained when the proportion of agents who a priori know the sensitivity is large, and the uninformed agents believe it is possible that the sensitivity is greater than 1.Asymmetric information, common knowledge, eductive learning, rational expectations, rationalizability, volatility.
Stabilizing through Poor Information
This paper studies the effect of asymmetric information on equilibrium stability in a class of linear models where the actual state depends on the forecasts about it. Stability is deffined by the so-called eductive criterion which relies on common knowledge of rationality. The main result is that stability obtains when the proportion of uninformed agents is high enough. The expectational behavior of these agents indeed displays more inertia. This behavior, and then the actual outcome, are therefore easier to predict. This result is linked to the issue of informational efficiency. Extensions to cases with higher order uncertainty, additional agents heterogeneity, and sunspots are also considered.Asymmetric information, eductive stability, rational expecta- tions, stabilization.
Stabilizing through Poor Information *
Abstract This paper studies the effect of asymmetric information on equilibrium stability in a class of linear models where the actual state depends on the forecasts about it. Stability is defined by the so-called eductive criterion which relies on common knowledge of rationality. The main result is that stability obtains when the proportion of uninformed agents is high enough. The expectational behavior of these agents indeed displays more inertia. This behavior, and then the actual outcome, are therefore easier to predict. This result is linked to the issue of informational efficiency. Extensions to cases with higher order uncertainty, additional agents' heterogeneity, and sunspots are also considered
Uniqueness of bubble-free solution in linear rational expectations models
International audienceOne usually identifies bubble solutions to linear rational expectations models by extra components (irrelevant lags) arising in addition to market fundamentals. Although there are still many solutions relying on a minimal set of state variables, i.e., relating in equilibrium the current state of the economic system to as many lags as initial conditions, there is a conventional wisdom that the bubble-free (fundamentals) solution should be unique. This paper examines the existence of endogenous stochastic sunspot fluctuations close to solutions relying on a minimal set of state variables, which provides a natural test for identifying bubble and bubble-free solutions. It turns out that only one solution is locally immune to sunspots, independently of the stability properties of the perfect-foresight dynamics. In the standard saddle-point configuration for these dynamics, this solution corresponds to the so-called saddle stable path
Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition
A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009â2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the worldâs planktonic ecosystems
Virtualia 2016. La réalité virtuelle au service de la recherche: Actes du séminaire organisé par le CIREVE à Caen (19 octobre 2016),
International audienceLe sĂ©minaire Virtualia est nĂ© en 2006 en mĂȘme temps que le Centre Interdisciplinaire de RĂ©alitĂ© Virtuelle (CIREVE) de lâUniversitĂ© de Caen Normandie. Son objectif est de permettre aux Ă©quipes associĂ©es au CIREVE dâexposer leurs mĂ©thodologies et les rĂ©sultats de leurs travaux dans le domaine de la RĂ©alitĂ© Virtuelle, tout en sâouvrant Ă des communications extĂ©rieures. Il a connu quatre Ă©ditions de 2006 Ă 2009.2016 fut lâoccasion de relancer VIRTUALIA et de concrĂ©tiser le partenariat avec les UniversitĂ©s de Rouen et du Havre dans le cadre de la COMUE. Une Structure FĂ©dĂ©rative de Recherche « CIREVE » est en effet en cours de labellisation au sein de Normandie UniversitĂ©. 2016 est Ă©galement une annĂ©e importante car elle marque Ă la fois le dixiĂšme anniversaire du CIREVE et la finalisation dâune plate-forme de rĂ©alitĂ© virtuelle normande, unique en son genre sur le territoire français. Elle est composĂ©e dâune salle immersive quatre faces de 45 m2, Ă©quipĂ©e dâun tapis roulant particuliĂšrement adaptĂ© pour lâanalyse de la marche en temps rĂ©el (GRAIL de Motek Medical). Les calculateurs de cette salle immersive sont mutualisĂ©s avec un amphithĂ©Ăątre attenant de 150 places, de maniĂšre que les expĂ©rimentations effectuĂ©es avec un sujet unique dans la salle immersive puissent ĂȘtre suivies par un auditoire nombreux (besoins de formation notamment). Les Ă©quipes utilisent le matĂ©riel au fur et Ă mesure des dĂ©veloppements informatiques et de nouveaux protocoles dâexpĂ©rimentation germent dans lâesprit des chercheurs qui voient dans la rĂ©alitĂ© virtuelle des possibilitĂ©s de tests jamais atteintes.Une centaine de chercheurs utilise rĂ©guliĂšrement le plateau technique CIREVE, dans des visĂ©es de recherche qui leur sont propres. Il est toutefois apparu quâun certain nombre de problĂ©matiques concernaient toutes les disciplines et quâune partie de la rĂ©flexion sur les mondes virtuels pouvait ĂȘtre mutualisĂ©e. Le sĂ©minaire VIRTUALIA permet dâoffrir un espace de rencontre Ă ces chercheurs, issus dâhorizons diffĂ©rents, pour discuter de lâutilisation de lâoutil dâun point de vue Ă©pistĂ©mologique. Il est par exemple capital de sâinterroger sur la notion de prĂ©sence. Le sujet se comporte-il de la mĂȘme façon dans lâenvironnement virtuel et dans le monde rĂ©el ? Les chemins de circulation choisis dans le modĂšle virtuel sont-ils les mĂȘmes que ceux qui seraient empruntĂ©s en rĂ©alitĂ© ? Les conclusions Ă©tablies dans le modĂšle virtuel sont-elles directement transposables Ă la rĂ©alitĂ© ? Un des enjeux du travail est dâĂ©valuer la pertinence subjective des modĂšles virtuels, ce qui est capital avant de gĂ©nĂ©raliser leur utilisation dans des actions de formation par exemple. Lâutilisation dâune technologie nâest jamais complĂštement neutre. Dans le cadre des mondes virtuels, lâinteraction de lâhomme avec le monde de synthĂšse nâest possible quâau travers de logiciels et dâinterfaces matĂ©rielles. Il faut sâassurer que les processus cognitifs soient adĂ©quats avant de sâinterroger sur le rĂ©sultat des simulations. Naturellement, le sĂ©minaire permet Ă©galement Ă chaque discipline dâexposer les rĂ©sultats des derniĂšres recherches rĂ©alisĂ©es grĂące Ă la rĂ©alitĂ© virtuelle.Les domaines scientifiques concernĂ©s par la rĂ©alitĂ© virtuelle sont multiples : les civilisations et les patrimoines culturels, la mĂ©decine, les neurosciences, la psychologie, les sciences du mouvement et du sport, lâingĂ©nierie, lâinformatique. LâUniversitĂ© de Caen Normandie Ă©tant pluridisciplinaire, le spectre des utilisations est trĂšs large. Elles se rĂ©partissent en trois axes principaux et un axe en Ă©mergence :LA REPRĂSENTATION : la rĂ©alitĂ© virtuelle permet de reprĂ©senter et de visualiser, interactivement et en trois dimensions, des environnements disparus, dĂ©gradĂ©s, inaccessibles, ou des environnements futurs.Domaines concernĂ©s : civilisations, patrimoine, linguistique...L'EXPĂRIMENTATION : en permettant d'interagir en temps rĂ©el avec un monde numĂ©rique 3D, la rĂ©alitĂ© virtuelle offre de nouvelles perspectives d'expĂ©rimentations dans des environnements de plus en plus proches du rĂ©el et en mĂȘme temps parfaitement contrĂŽlables.Domaines concernĂ©s : santĂ©, neuropsychologie, psychologie, activitĂ©s physiques et sportives...LA CREATION ET LE DEVELOPPEMENT DâOUTILS : les informaticiens crĂ©ent et testent des applications concernant les mĂ©thodes de navigation en monde virtuel, de restitution de la rĂ©alitĂ©.Domaine concernĂ© : informatique.LA FORMATION (axe en Ă©mergence) : par la reprĂ©sentation de la connaissance, par les diverses possibilitĂ©s d'expĂ©rimentation, la rĂ©alitĂ© virtuelle est un formidable outil de formation.Domaines concernĂ©s : sciences du langage, mĂ©decine, informatique (serious game, simulation...).Une partie importante de la rĂ©flexion dĂ©veloppĂ©e lors du sĂ©minaire Virtualia 2016 a Ă©tĂ© consacrĂ©e aux enjeux sociĂ©taux liĂ©s Ă la rĂ©alitĂ© virtuelle : notions de mĂ©moire, dâapprentissage des gestes techniques, dâĂȘtre humain « augmentĂ© » etc. Les articles publiĂ©s attestent du savoir-faire, bien rĂ©el cette fois, que le CIREVE a acquis en termes de crĂ©ation de mondes virtuels pour reprĂ©senter, expĂ©rimenter et former. La publication des actes du sĂ©minaire Virtualia vise Ă mettre en lumiĂšre des recherches particuliĂšrement innovantes qui sâeffectuent dans un cadre technologique exceptionnel.- S. Madeleine, Virtualia 2016. Introduction (et direction de l'Ă©dition)- J. Grieu, F. Lecroq, Th. Galinho, H. Boukachour, Environnements industriels virtualisĂ©s et processus dâapprentissage- Ph. Brunet, J. Dehut, Images 3D et humanitĂ©s numĂ©riques : modĂ©lisation et restitution du geste thĂ©Ăątral- G. Lecouvey, J. Gonneaud, N. Legrand, G. Rauchs, F. Eustache, B. Desgranges, RĂ©alitĂ© virtuelle et mĂ©moire- N. Benguigui, C. Mandil, M. Mallek, L. Lejeune, R. Thouvarecq, Ătude des liens entre perception et action dans des environnements virtuels- E.-G. Dupuy, A. Maneuvrier, E. Vlamynck, S. Besnard, B. Bienvenu, L.-M. Decker, Le syndrome dâEhlers-Danlos type hypermobile : Ă©volution des stratĂ©gies posturales en rĂ©ponse Ă un programme de rĂ©Ă©ducation Ă visĂ©e somesthĂ©sique- C. Weismann-Arcache, RĂ©alitĂ© virtuelle et humain augmentĂ© : subjectivation, dĂ©subjectivation ?- L. Haddouk, RĂ©alitĂ© psychique en visioconsultatio
Viral to metazoan marine plankton nucleotide sequences from the Tara Oceans expedition
A unique collection of oceanic samples was gathered by the Tara Oceans expeditions (2009-2013), targeting plankton organisms ranging from viruses to metazoans, and providing rich environmental context measurements. Thanks to recent advances in the field of genomics, extensive sequencing has been performed for a deep genomic analysis of this huge collection of samples. A strategy based on different approaches, such as metabarcoding, metagenomics, single-cell genomics and metatranscriptomics, has been chosen for analysis of size-fractionated plankton communities. Here, we provide detailed procedures applied for genomic data generation, from nucleic acids extraction to sequence production, and we describe registries of genomics datasets available at the European Nucleotide Archive (ENA, www.ebi.ac.uk/ena). The association of these metadata to the experimental procedures applied for their generation will help the scientific community to access these data and facilitate their analysis. This paper complements other efforts to provide a full description of experiments and open science resources generated from the Tara Oceans project, further extending their value for the study of the world's planktonic ecosystems
Fundamental Volatility and Financial Stability
Financial investors choose the capital they invest into risky firms based on the return they expect. The actual return depends on fundamental shocks and the aggregate investment, which gives rise to beauty-contest issues. The paper characterizes how the ability of investors to solve these issues relates to the amount of fundamental volatility. It exploits this link to provide a quantitative assessment of the contribution of fundamentals to market volatility. Volatility would be driven by fundamentals in most markets. However out-ofequilibrium beliefs significantly contribute to observed volatility in markets of the financial sector