Teses / dissertações sobre o tema "Échelles (sciences sociales) – Modèles mathématiques"
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Veja os 38 melhores trabalhos (teses / dissertações) para estudos sobre o assunto "Échelles (sciences sociales) – Modèles mathématiques".
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Schmeltzer, Christophe. "Apparition et disparition du renversement de préférence : effet du mode d'évaluation". Aix-Marseille 1, 2002. http://www.theses.fr/2002AIX10067.
Texto completo da fonteHérault, Stéphanie. "Étude des processus de formation de l'attitude envers la marque : un essai de modélisation intégrant une variable psychologique, la confiance en soi : une application en situation de pré-test publicitaire pour des produits de grande consommation". Paris 1, 1999. http://www.theses.fr/1999PA010065.
Texto completo da fonteLe, Moine Veillon Clément. "Neural Conversion of Social Attitudes in Speech Signals". Electronic Thesis or Diss., Sorbonne université, 2023. https://accesdistant.sorbonne-universite.fr/login?url=https://theses-intra.sorbonne-universite.fr/2023SORUS034.pdf.
Texto completo da fonteAs social animals, humans communicate with each other by transmitting various types of information about the world and about themselves. At the heart of this process, the voice allows the transmission of linguistic messages denoting a strict meaning that can be decoded by the interlocutor. By conveying other information such as attitudes or emotions that connote the strict meaning, the voice enriches and enhances the communication process. In the last few decades, the digital world has become an important part of our lives. In many everyday situations, we are moving away from keyboards, mice and even touch screens to interactions with voice assistants or even virtual agents that enable human-like communication with machines. In the emergence of a hybrid world where physical and virtual reality coexist, it becomes crucial to enable machines to capture, interpret, and replicate the emotions and attitudes conveyed by the human voice.This research focuses on speech social attitudes, which can be defined - in a context of interaction - as speech dispositions towards others and aims to develop algorithms for their conversion. Fulfilling this objective requires data, i.e. a collection of audio recordings of utterances conveying various vocal attitudes. This research is thus built out of this initial step in gathering raw material - a dataset dedicated to speech social attitudes. Designing such algorithms involves a thorough understanding of what these attitudes are both in terms of production - how do individuals use their vocal apparatus to produce attitudes? - and perception - how do they decode those attitudes in speech? We therefore conducted two studies, a first uncovering the production strategies of speech attitudes and a second - based on a Best Worst Scaling (BWS) experiment - mainly hinting at biases involved in the perception such vocal attitudes, thus providing a twofold account for how speech attitudes are communicated by French individuals. These findings were the basis for the choice of speech signal representation as well as the architectural and optimisation choices for the design of a speech attitude conversion algorithm. In order to extend the knowledge on the perception of vocal attitudes gathered during this second study to the whole database, we worked on the elaboration of a BWS-Net allowing the detection of mis-communicated attitudes, and thus provided clean data for conversion learning. In order to learn how to convert vocal attitudes, we adopted a transformer-based approach in a many-to-many conversion paradigm with mel-spectrogram as speech signal representation. Since early experiments revealed a loss of intelligibility in the converted utterances, we proposed a linguistic conditioning of the conversion algorithm through incorporation of a speech-to-text module. Both objective and subjective measures have shown the resulting algorithm achieves better performance than the baseline transformer both in terms of intelligibility and attitude conveyed
Perin, Matthieu. "Contribution à la modélisation réaliste et multi-échelles des systèmes bouclés temporisés". Phd thesis, École normale supérieure de Cachan - ENS Cachan, 2012. http://tel.archives-ouvertes.fr/tel-00753503.
Texto completo da fonteAugeraud-Veron, Emmanuelle. "L'anticipation dans les modèles à générations imbriquées". La Rochelle, 2000. http://www.theses.fr/2000LAROS059.
Texto completo da fonteMissoum, Benziane Djamel. "Nouvelle approche pour la modélisation des problèmes multi-échelles en mécanique : la méthode 95/5". Phd thesis, Paris, ENSAM, 2007. http://pastel.archives-ouvertes.fr/pastel-00002617.
Texto completo da fonteDetandt-Feys, Brigitte. "La performance de l'entreprise est souvent approchée par un coefficient prenant en considération la valeur moyenne du titre, le taux des certificats de tresorerie et le coefficient "Beta" (mesure du risque du titre): [thèse annexe]". Doctoral thesis, Universite Libre de Bruxelles, 1986. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213538.
Texto completo da fonteSengès, Eloïse. "Antécédents, manifestations et effets du Bien Vieillir Désiré sur la consommation des seniors". Thesis, Paris Sciences et Lettres (ComUE), 2016. http://www.theses.fr/2016PSLED033.
Texto completo da fonteAging well is now a key stake for senior marketing, yet this concept remains little investigated by consumer research. A new concept is introduced in marketing research: Desired Aging Well (DAW), which refers to the psychological, physical, social and financial objectives, pursued in the quest for aging well. This research provides a reliable and valid bifactor measurement model for Desired Aging Well, in four dimensions: general DAW, physical DAW, social DAW and financial DAW. Its influence is tested on eight consumer behaviors related to the following sectors: food, e-health, plastic surgery, leisure, financial investments, social networks and dating sites. The Desired Aging Well scale and the overall antecedents-manifestations-effects model are validated on a sample of 900 French senior people aged from 50 to 80. The results suggest the development of a new marketing approach for seniors: aging well marketing. Its investigation and implementation are rooted in four key concepts: Desired Aging Well, perceived aging, adjustment to aging expectations and aging well consumption
Nardetto, Nicolas. "La dynamique atmosphérique des Céphéides et l'étalonnage des échelles de distance dans l'Univers". Phd thesis, Université de Nice Sophia-Antipolis, 2005. http://tel.archives-ouvertes.fr/tel-00069295.
Texto completo da fontePriser, Mathieu. "Analyses multi-échelles du comportement en fluage d'alliages de zirconium". Phd thesis, Université de Bretagne Sud, 2011. http://tel.archives-ouvertes.fr/tel-00642008.
Texto completo da fonteDurand, Julian. "Approche multi-échelles des problèmes de contact et d'étanchéité". Phd thesis, Ecole Nationale Supérieure des Mines de Paris, 2012. http://pastel.archives-ouvertes.fr/pastel-00820173.
Texto completo da fonteSekkat, Khalid. "Stratégies verticales dans les filières: limites et substituts de l'intégration". Doctoral thesis, Universite Libre de Bruxelles, 1989. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/213229.
Texto completo da fonteTerry, Emmanuelle. "Modélisation mathématique des dynamiques de la réponse immunitaire T CD8, aux échelles cellulaire et moléculaire". Phd thesis, Université Claude Bernard - Lyon I, 2012. http://tel.archives-ouvertes.fr/tel-00763897.
Texto completo da fontePeter, Anne-Charlotte. "Variabilité de la température de la couche de mélange océanique en Atlantique équatorial aux échelles saisonnières à interannuelles, à l'aide de simulations numériques". Phd thesis, Université Paul Sabatier - Toulouse III, 2007. http://tel.archives-ouvertes.fr/tel-00157983.
Texto completo da fonteLes résultats obtenus montrent la prédominance des processus verticaux et des ondes tropicales d'instabilité (<35jours, ~500km) pour expliquer la variabilité de la température de la couche de surface à l'échelle annuelle.
L'étude d'évènements interannuels a permis de distinguer deux processus distincts responsables de la variabilité interannuelle de la température de surface : l'un dynamique et distant crée par les anomalies de vent dans l'ouest du bassin et agissant par l'intermédiaire de la propagation d'ondes de Kelvin équatoriales et le second, thermodynamique et local à l'échelle du Golfe de Guinée, créé par les anomalies interannuelles de flux de chaleur.
Jars, Isabelle. "Contribution des Sciences Sociales dans le domaine de l'Intelligence Artificielle Distribuée : ALONE, un modèle hybride d'agent apprenant". Phd thesis, Université Claude Bernard - Lyon I, 2005. http://tel.archives-ouvertes.fr/tel-00011135.
Texto completo da fonteRodriguez, Zoya Leonardo Gabriel. "Le modèle épistémologique de la pensée complexe : analyse critique de la construction de la connaissance en systèmes complexes". Thesis, Toulouse 1, 2013. http://www.theses.fr/2013TOU10032/document.
Texto completo da fonteThis PhD thesis develops an empirically grounded and critical epistemological research on scientific knowledge construction in the community of researchers working on complex systems and social simulation. The goal of this Thesis is to establish a complex epistemology for the critical study of the process of construction, organization and change of scientific knowledge. To do this, we construct an epistemological model of the complex thought [MEPC] which provides a theoretical framework and guides the empirical methodology. We investigate the dynamics and the organization of scientific knowledge in field of complex systems and social simulation in three temporal scales: the long, average and short duration. The construction of the MEPC is grounded in the complex thought, proposed by Edgar Morin and it integrates theoretical contributions from complex systems sciences and computational modeling and simulation methods. The MEPC is empirically operational in order to analyze concrete phenomena and to submit to empirical test its theoretical postulates. The MEPC is used to conduct an empirical research which goal is to understand the organization of the system of scientific beliefs of complex system science and social simulation, using this evidence to critically explain knowledge construction in this scientific field
Esta Tesis desarrolla una investigación epistemológica empírica y crítica sobre la construcción de conocimiento científico en la comunidad de investigadores que trabajan en sistemas complejos y simulación social. El propósito de la Tesis es elaborar los fundamentos de una epistemología compleja para el estudio crítico de los procesos de construcción, organización y cambio del conocimiento científico. Para este fin, se construye el modelo epistemológico del pensamiento complejo [MEPC] que brinda un marco teórico y orienta la metodología empírica diseñada. Se estudia la dinámica y la organización del conocimiento científico en el campo de los sistemas complejos y de la simulación social en tres escalas temporales: la larga, la media y la corta duración. La construcción del MEPC se fundamenta en el pensamiento complejo desarrollado por Edgar Morin y articula aportes teóricos de las ciencias de los sistemas complejos y de los métodos de modelado y simulación. El MEPC es operacionalizado empíricamente para permitir el análisis de fenómenos concretos y someter al test de la experiencia empírica la validez de sus postulados teóricos. Se emplea el MEPC en una investigación empírica con el objetivo de comprender la organización del sistema de creencias científicas de las ciencias de los sistemas complejos y de la simulación social, y de interpretar críticamente la construcción de conocimiento que dichas ciencias realizan
Beine, Michel. "Union monétaire européenne et théorie des zones monétaires optimales". Doctoral thesis, Universite Libre de Bruxelles, 1996. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212285.
Texto completo da fonteDalud-Vincent, Monique. "Modèle prétopologique pour une méthodologie d'analyse de réseaux : concepts et algorithmes". Lyon 1, 1994. http://www.theses.fr/1994LYO10040.
Texto completo da fonteDe, Antonio Liedo David. "Structural models for macroeconomics and forecasting". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210142.
Texto completo da fontecentral debates in empirical macroeconomic modeling.
Chapter 1, entitled “A Model for Real-Time Data Assessment with an Application to GDP Growth Rates”, provides a model for the data
revisions of macroeconomic variables that distinguishes between rational expectation updates and noise corrections. Thus, the model encompasses the two polar views regarding the publication process of statistical agencies: noise versus news. Most of the studies previous studies that analyze data revisions are based
on the classical noise and news regression approach introduced by Mankiew, Runkle and Shapiro (1984). The problem is that the statistical tests available do not formulate both extreme hypotheses as collectively exhaustive, as recognized by Aruoba (2008). That is, it would be possible to reject or accept both of them simultaneously. In turn, the model for the
DPP presented here allows for the simultaneous presence of both noise and news. While the “regression approach” followed by Faust et al. (2005), along the lines of Mankiew et al. (1984), identifies noise in the preliminary
figures, it is not possible for them to quantify it, as done by our model.
The second and third chapters acknowledge the possibility that macroeconomic data is measured with errors, but the approach followed to model the missmeasurement is extremely stylized and does not capture the complexity of the revision process that we describe in the first chapter.
Chapter 2, entitled “Revisiting the Success of the RBC model”, proposes the use of dynamic factor models as an alternative to the VAR based tools for the empirical validation of dynamic stochastic general equilibrium (DSGE) theories. Along the lines of Giannone et al. (2006), we use the state-space parameterisation of the factor models proposed by Forni et al. (2007) as a competitive benchmark that is able to capture weak statistical restrictions that DSGE models impose on the data. Our empirical illustration compares the out-of-sample forecasting performance of a simple RBC model augmented with a serially correlated noise component against several specifications belonging to classes of dynamic factor and VAR models. Although the performance of the RBC model is comparable
to that of the reduced form models, a formal test of predictive accuracy reveals that the weak restrictions are more useful at forecasting than the strong behavioral assumptions imposed by the microfoundations in the model economy.
The last chapter, “What are Shocks Capturing in DSGE modeling”, contributes to current debates on the use and interpretation of larger DSGE
models. Recent tendency in academic work and at central banks is to develop and estimate large DSGE models for policy analysis and forecasting. These models typically have many shocks (e.g. Smets and Wouters, 2003 and Adolfson, Laseen, Linde and Villani, 2005). On the other hand, empirical studies point out that few large shocks are sufficient to capture the covariance structure of macro data (Giannone, Reichlin and
Sala, 2005, Uhlig, 2004). In this Chapter, we propose to reconcile both views by considering an alternative DSGE estimation approach which
models explicitly the statistical agency along the lines of Sargent (1989). This enables us to distinguish whether the exogenous shocks in DSGE
modeling are structural or instead serve the purpose of fitting the data in presence of misspecification and measurement problems. When applied to the original Smets and Wouters (2007) model, we find that the explanatory power of the structural shocks decreases at high frequencies. This allows us to back out a smoother measure of the natural output gap than that
resulting from the original specification.
Doctorat en Sciences économiques et de gestion
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Godard, Caroline. "Modélisation de la réponse à l'azote du rendement des grandes cultures et intégration dans un modèle économique d'offre agricole à l'échelle européenne : application à l'évaluation des impacts du changement climatique". Phd thesis, INAPG (AgroParisTech), 2005. http://pastel.archives-ouvertes.fr/pastel-00002852.
Texto completo da fonteRagazzi, Graziella. "Les Modèles Economiques dans la Transition Energétique bas carbone à l'Echelle Locale". Thesis, Paris Sciences et Lettres (ComUE), 2018. http://www.theses.fr/2018PSLED052/document.
Texto completo da fonteTo face the climate change, energy transition is required. Energy transition is a societal transition, which is really challenging because of its singularities. The multi-level governance is necessary in order to act now for the energy transition. Indeed States take action by negotiating international agreements for the climate on the one hand, and on the other hand by legislating their national regulatory framework. Local authorities intervene too owing to their competencies which give them a high influence power on decentralized production system and on energy consumption. The local scale plays a major role because they benefit from closed and trustful relationships which foster collective action and act as a real leverage. It is at the territories level that energy transition projects emerge and that fight against global warming become true. That's why it is necessary to understand what types of local projects for the energy transition arise, and what is their economic, social and environmental performance. This can allow public authorities to identify what are the performant projects and to encourage to replicate them on the one hand, and on the other hand to remove barriers in order to make arise innovant projects. In the long run, we must understand what kinds of projects will unfold and generalize as part of the energy transition depending on the value they will generate. To answer this, the business models perspective is highly appropriate: it constitutes an analytical framework which allows to describe the project features (its value proposition, its value configuration) and to determine its viability and sustainability according to the (economic, financial, social, environmental) values creation it builds. The thesis puts forward a typology of energy transition business models at the local scale, an analytical framework for projects adapted to the energy transition societal stake. Finally the thesis suggests some public policy recommandation in terms of assessment of the economic, social and environmental performance of the local projects for the energy transition
Mazaleyrat, Guillaume. "Modélisation multi échelles de la croissance des oxydes à fortes permittivités : simulation Monte-Carlo cinétique". Phd thesis, Université Paul Sabatier - Toulouse III, 2006. http://tel.archives-ouvertes.fr/tel-00011574.
Texto completo da fontePecquery, François. "Développement d'un modèle numérique de prédiction des émissions d'oxydes d'azote pour la simulation aux grandes échelles de chambres de combustion aéronautiques". Phd thesis, INSA de Rouen, 2013. http://tel.archives-ouvertes.fr/tel-00949132.
Texto completo da fonteCastro, Carlos. "Essays in dependence and optimality in large portfolios". Doctoral thesis, Universite Libre de Bruxelles, 2010. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210186.
Texto completo da fontemodeling and estimating the dependence structure for a large portfolio of assets using rating data.
In both chapters a natural form of organizing a portfolio in terms of the levels of exposure to economic sectors and geographical regions, plays a key role in setting up the dependence structure.
The last chapter investigates weather financial strategies that exploit sector or geographical heterogeneity in the asset space are relevant in terms of portfolio optimization. This is also done in a context of a large portfolio but with data on stock returns.
Doctorat en Sciences économiques et de gestion
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Lalloué, Benoît. "Méthodes d'analyse de données et modèles bayésiens appliqués au contexte des inégalités socio-territoriales de santé et des expositions environnementales". Phd thesis, Université de Lorraine, 2013. http://tel.archives-ouvertes.fr/tel-00943004.
Texto completo da fonteEl, Janyani Sanae. "Incidence des bétoires et de la karstogenèse des plateaux crayeux de la Haute-Normandie sur le fonctionnement hydrologique de l'aquifère de la craie : modélisation hydrogéologique des influences climatiques à différentes échelles spatio-temporelles". Phd thesis, Université de Rouen, 2013. http://tel.archives-ouvertes.fr/tel-00920267.
Texto completo da fonteJaniak, Alexandre. "Essais sur la mobilité géographique, sectorielle et intra-sectorielle en périodes de changement structurel : le rôle du capital humain, du capital social et de l'ouverture aux échanges". Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210600.
Texto completo da fonteLe changement structurel est un processus nécessaire qui améliore considérablement les conditions de vie dans nos sociétés. Il peut découler par exemple de l'introduction de nouvelles avancées technologiques qui permettent d'augmenter à long terme la productivité agrégée dans nos économies. En retour, la hausse de la productivité a un impact sur notre consommation de tous les jours. Elle nous permet notamment de vivre dans un plus grand confort. Les individus peuvent alors s'épanouir dans leur ensemble. Il est évident que le changement structurel peut prendre d'autres formes que celle du changement technologique, mais il est souvent issu d'une transformation des forces qui influencent les marchés et en général aboutit à long terme à une amélioration du bien-être global.
Mais le changement structurel est aussi un processus douloureux. Il peut durer plusieurs décennies et, durant cette période, nous sommes beaucoup à devoir en supporter les coûts. Comme nous allons l'illustrer dans ce chapitre introductif, le changement structurel a pour conséquence une modification du rapport aux facteurs de production, ce qui alors mène à modifier l'ensemble des prix relatifs qui caractérisent une économie. En particulier, la modification des prix est due à une transformation des demandes relatives de facteurs. Ces derniers se révèlent alors inutiles à l'exécution de certaines tâches ou sont fortement demandés dans d'autres points de l'économie.
Souvent, le changement structurel entraîne alors un processus de réallocation. Des pans entiers de travailleurs doivent par conséquent se réallouer à d'autres tâches. Les lois du marché les incitent ainsi à devoir s'adapter à un nouveau contexte, mais elles le font pour un futur meilleur.
Cette thèse s'intéresse à cette problématique. Elle suppose que tout processus de changement structurel implique un mouvement de réallocation des facteurs de production, notamment des travailleurs puisqu'il s'agit d'une thèse en économie du travail, mais qu'un tel processus engendre souvent des coûts non négligeables. Elle se veut surtout positive, mais la nature des questions qu'elle pose mène naturellement à un débat normatif. Par exemple, elle cherche des réponses aux interrogations suivantes: comment s'ajuste une économie au changement structurel? Quelle est la nature des coûts associés au changement? Ces coûts peuvent-ils en excéder les gains? Le processus de réallocation en vaut-il vraiment la peine? Les gains issus d'un tel processus sont-ils distribués de manière égale?
La thèse est composée de quatre chapitres qui chacun considère l’impact d’un changement structurel particulier.
Le premier chapitre s’intéresse à l’impact de l’ouverture internationale aux échanges sur le niveau de l’emploi. Il s’appuie sur des travaux récents en économie internationale qui ont montré que la libéralisation du commerce mène à l’expansion des firmes les plus productives et à la destruction des entreprises dont la productivité est moins élevée. La raison de cette dichotomie est la présence d’un coût à l’entrée sur le marché des exports qui a été documentée par de nombreuses études. Certaines entreprises se développent suite à la libéralisation car elles ont accès à de nouveaux marchés et d’autres meurent car elles ne peuvent pas faire face aux entreprises les plus productives. Puisque le commerce crée à la fois des emplois et en détruit d’autres, ce chapitre a pour but de déterminer l’effet net de ce processus de réallocation sur le niveau agrégé de l’emploi.
Dans cette perspective, il présente un modèle avec firmes hétérogènes où pour exporter une entreprise doit payer un coût fixe, ce qui implique que seules les entreprises les plus productives peuvent entrer sur le marché international. Le modèle génère le processus de réallocation que l’ouverture au commerce international suppose. En effet, comme les entreprises les plus productives veulent exporter, elles vont donc embaucher plus de travailleurs, mais comme elles sont également capables de fixer des prix moins élevés et que les biens sont substituables, les entreprises les moins productives vont donc faire faillite. L’effet net sur l’emploi est négatif car les exportateurs ont à la marge moins d’incitants à embaucher des travailleurs du au comportement de concurrence monopolistique.
Le chapitre analyse également d’un point de vue empirique l’effet d’une ouverture au commerce au niveau sectoriel sur les flux d’emplois. Les résultats empiriques confirment ceux du modèle, c’est-à-dire qu’une hausse de l’ouverture au commerce génère plus de destructions que de créations d’emplois au niveau d’un secteur.
Le second chapitre considère un modèle similaire à celui du premier chapitre, mais se focalise plutôt sur l’effet du commerce en termes de bien-être. Il montre notamment que l’impact dépend en fait de la courbe de demande de travail agrégée. Si la courbe est croissante, l’effet est positif, alors qu’il est négatif si elle est décroissante.
Le troisième chapitre essaie de comprendre quels sont les déterminants de la mobilité géographique. Le but est notamment d’étudier le niveau du chômage en Europe. En effet, la littérature a souvent affirmé que la faible mobilité géographique du travail est un facteur de chômage lorsque les travailleurs sans emploi préfèrent rester dans leur région d’origine plutôt que d’aller prospecter dans les régions les plus dynamiques. Il semble donc rationnel pour ces individus de créer des liens sociaux locaux si ils anticipent qu’ils ne déménageront pas vers une autre région. De même, une fois le capital social local accumulé, les incitants à la mobilité sont réduits.
Le troisième chapitre illustre donc un modèle caractérisé par diverses complémentarités qui mènent à des équilibres multiples (un équilibre avec beaucoup de capital social local, peu de mobilité et un chômage élevé et un autre avec des caractéristiques opposées). Le modèle montre également que le capital social local est systématiquement négatif pour la mobilité et peut être négatif pour l’emploi, mais d’autres types de capital social peuvent en fait faire augmenter le niveau de l’emploi.
Dans ce troisième chapitre, une illustration empirique qui se base sur plusieurs mesures montre que le capital social est un facteur dominant d’immobilité. C’est aussi un facteur de chômage lorsque le capital social est clairement local, alors que d’autres types de capital social s’avèrent avoir un effet positif sur le taux d’emploi. Cette partie empirique illustre également la causalité inverse où des individus qui vivent dans une région qui ne correspond pas à leur région de naissance accumulent moins de capital social local, ce qui donne de la crédibilité à une théorie d’équilibres multiples.
Finalement, en observant que les individus dans le Sud de l’Europe semblent accumuler plus de capital social local, alors que dans le Nord de l’Europe on tend à investir dans des types plus généraux de capital social, nous suggérons qu’une partie du problème de chômage en Europe peut mieux se comprendre grâce au concept de capital social local.
Enfin, le quatrième chapitre s’intéresse à l’effet de la croissance économique sur la qualité des emplois. En particulier, il analyse le fait qu’un individu puisse avoir un emploi qui corresponde ou non à ses qualifications, ce qui, dans le contexte de ce chapitre, détermine s’il s’agit de bons ou mauvais emplois.
Ce chapitre se base sur deux mécanismes qui ont été largement abordés par la littérature. Le premier est le concept de « destruction créatrice » qui dit que la croissance détruit de nouveaux emplois car elle les rend obsolètes. Le second est le processus de « capitalisation » qui nous dit que la croissance va créer de nombreux emplois car les entreprises anticipent des profits plus élevés dans le futur.
Alors que des études récentes, suggèrent que la destruction créatrice ne permet pas d’expliquer le lien entre croissance et chômage, ce chapitre montre qu’un tel concept permet de mieux comprendre la relation entre croissance et qualité des emplois.
Avec des données issues du panel européen, nous illustrons que la corrélation entre croissance et qualité des emplois est positive. Nous présentons une série de trois modèles qui diffèrent de la manière suivante :(i) le fait de pouvoir chercher un emploi ou non alors qu’on en a déjà un, (ii) le fait pour une entreprise de pouvoir acquérir des équipements modernes. Les résultats suggèrent que pour expliquer l’effet de la croissance sur la qualité des emplois, la meilleure stratégie est une combinaison entre les effets dits de destruction créatrice et de capitalisation. Alors que le premier effet influence le taux de destruction des mauvais emplois, le second a un impact sur la mobilité du travail des mauvais vers les bons emplois.
Doctorat en Sciences économiques et de gestion
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Tremblay-Auger, Benjamin, e Benjamin Tremblay-Auger. "Réputation, identités transnationales et soutien étranger de rébellions". Master's thesis, Université Laval, 2019. http://hdl.handle.net/20.500.11794/37256.
Texto completo da fonteTableau d’honneur de la Faculté des études supérieures et postdoctorales, 2019-2020.
Les États s’impliquent-ils parfois dans des conflits pour promouvoir une réputation de fermeté? Je revisite cette question fondamentale des relations internationales en l’étudiant dans un nouveau contexte. J’analyse les cas où des États soutiennent des rébellions de populations extérieures avec lesquelles ils ont des liens ethniques, religieux ou idéologiques. Je fais l’hypothèse que les États s’investissent dans certains de ces conflits afin de développer une réputation d’État défenseur d’une identité transnationale. Cette réputation leur permet de favoriser l’inclusion d’autres groupes co-identitaires ou d’obtenir des concessions en lien avec des enjeux internationaux. Puisque la construction de la réputation ne peut pas être observée directement, j’étudie des preuves indirectes de son existence. J’utilise un modèle formel inspiré de Kreps etWilson (1982) pour dériver trois prédictions directement reliées au mécanisme de la réputation: 1) Plus un État a de disputes avec d’autres pays en lien avec des groupes co-identitaires, plus il est probable qu’il soutienne une rébellion; 2) Plus un État a de disputes, plus il est probable que les groupes co-identitaires soient inclus politiquement dans leur pays; 3) Plus l’un de ces groupes est fort par rapport à son gouvernement, moins l’effet du nombre de disputes sur la probabilité qu’il se révolte est important. Pour tester ces prédictions, j’utilise des données sur les liens ethniques transnationaux, l’inclusion politique des groupes ethniques et le soutien étatique de groupes rebelles entre 1946 et 2010. Ces données riches me permettent de contourner certains des problèmes d’endogénéité et de taille d’échantillon qui affectent les études précédentes sur la réputation des États. J’obtiens des résultats cohérents avec mes prédictions, mais qui ne sont pas robustes à toutes les spécifications et tous les tests de robustesse.
Les États s’impliquent-ils parfois dans des conflits pour promouvoir une réputation de fermeté? Je revisite cette question fondamentale des relations internationales en l’étudiant dans un nouveau contexte. J’analyse les cas où des États soutiennent des rébellions de populations extérieures avec lesquelles ils ont des liens ethniques, religieux ou idéologiques. Je fais l’hypothèse que les États s’investissent dans certains de ces conflits afin de développer une réputation d’État défenseur d’une identité transnationale. Cette réputation leur permet de favoriser l’inclusion d’autres groupes co-identitaires ou d’obtenir des concessions en lien avec des enjeux internationaux. Puisque la construction de la réputation ne peut pas être observée directement, j’étudie des preuves indirectes de son existence. J’utilise un modèle formel inspiré de Kreps etWilson (1982) pour dériver trois prédictions directement reliées au mécanisme de la réputation: 1) Plus un État a de disputes avec d’autres pays en lien avec des groupes co-identitaires, plus il est probable qu’il soutienne une rébellion; 2) Plus un État a de disputes, plus il est probable que les groupes co-identitaires soient inclus politiquement dans leur pays; 3) Plus l’un de ces groupes est fort par rapport à son gouvernement, moins l’effet du nombre de disputes sur la probabilité qu’il se révolte est important. Pour tester ces prédictions, j’utilise des données sur les liens ethniques transnationaux, l’inclusion politique des groupes ethniques et le soutien étatique de groupes rebelles entre 1946 et 2010. Ces données riches me permettent de contourner certains des problèmes d’endogénéité et de taille d’échantillon qui affectent les études précédentes sur la réputation des États. J’obtiens des résultats cohérents avec mes prédictions, mais qui ne sont pas robustes à toutes les spécifications et tous les tests de robustesse.
Bañbura, Marta. "Essays in dynamic macroeconometrics". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210294.
Texto completo da fonteThe first two chapters consider factor models in the context of real-time forecasting with many indicators. Using a large number of predictors offers an opportunity to exploit a rich information set and is also considered to be a more robust approach in the presence of instabilities. On the other hand, it poses a challenge of how to extract the relevant information in a parsimonious way. Recent research shows that factor models provide an answer to this problem. The fundamental assumption underlying those models is that most of the co-movement of the variables in a given dataset can be summarized by only few latent variables, the factors. This assumption seems to be warranted in the case of macroeconomic and financial data. Important theoretical foundations for large factor models were laid by Forni, Hallin, Lippi and Reichlin (2000) and Stock and Watson (2002). Since then, different versions of factor models have been applied for forecasting, structural analysis or construction of economic activity indicators. Recently, Giannone, Reichlin and Small (2008) have used a factor model to produce projections of the U.S GDP in the presence of a real-time data flow. They propose a framework that can cope with large datasets characterised by staggered and nonsynchronous data releases (sometimes referred to as “ragged edge”). This is relevant as, in practice, important indicators like GDP are released with a substantial delay and, in the meantime, more timely variables can be used to assess the current state of the economy.
The first chapter of the thesis entitled “A look into the factor model black box: publication lags and the role of hard and soft data in forecasting GDP” is based on joint work with Gerhard Rünstler and applies the framework of Giannone, Reichlin and Small (2008) to the case of euro area. In particular, we are interested in the role of “soft” and “hard” data in the GDP forecast and how it is related to their timeliness.
The soft data include surveys and financial indicators and reflect market expectations. They are usually promptly available. In contrast, the hard indicators on real activity measure directly certain components of GDP (e.g. industrial production) and are published with a significant delay. We propose several measures in order to assess the role of individual or groups of series in the forecast while taking into account their respective publication lags. We find that surveys and financial data contain important information beyond the monthly real activity measures for the GDP forecasts, once their timeliness is properly accounted for.
The second chapter entitled “Maximum likelihood estimation of large factor model on datasets with arbitrary pattern of missing data” is based on joint work with Michele Modugno. It proposes a methodology for the estimation of factor models on large cross-sections with a general pattern of missing data. In contrast to Giannone, Reichlin and Small (2008), we can handle datasets that are not only characterised by a “ragged edge”, but can include e.g. mixed frequency or short history indicators. The latter is particularly relevant for the euro area or other young economies, for which many series have been compiled only since recently. We adopt the maximum likelihood approach which, apart from the flexibility with regard to the pattern of missing data, is also more efficient and allows imposing restrictions on the parameters. Applied for small factor models by e.g. Geweke (1977), Sargent and Sims (1977) or Watson and Engle (1983), it has been shown by Doz, Giannone and Reichlin (2006) to be consistent, robust and computationally feasible also in the case of large cross-sections. To circumvent the computational complexity of a direct likelihood maximisation in the case of large cross-section, Doz, Giannone and Reichlin (2006) propose to use the iterative Expectation-Maximisation (EM) algorithm (used for the small model by Watson and Engle, 1983). Our contribution is to modify the EM steps to the case of missing data and to show how to augment the model, in order to account for the serial correlation of the idiosyncratic component. In addition, we derive the link between the unexpected part of a data release and the forecast revision and illustrate how this can be used to understand the sources of the
latter in the case of simultaneous releases. We use this methodology for short-term forecasting and backdating of the euro area GDP on the basis of a large panel of monthly and quarterly data. In particular, we are able to examine the effect of quarterly variables and short history monthly series like the Purchasing Managers' surveys on the forecast.
The third chapter is entitled “Large Bayesian VARs” and is based on joint work with Domenico Giannone and Lucrezia Reichlin. It proposes an alternative approach to factor models for dealing with the curse of dimensionality, namely Bayesian shrinkage. We study Vector Autoregressions (VARs) which have the advantage over factor models in that they allow structural analysis in a natural way. We consider systems including more than 100 variables. This is the first application in the literature to estimate a VAR of this size. Apart from the forecast considerations, as argued above, the size of the information set can be also relevant for the structural analysis, see e.g. Bernanke, Boivin and Eliasz (2005), Giannone and Reichlin (2006) or Christiano, Eichenbaum and Evans (1999) for a discussion. In addition, many problems may require the study of the dynamics of many variables: many countries, sectors or regions. While we use standard priors as proposed by Litterman (1986), an
important novelty of the work is that we set the overall tightness of the prior in relation to the model size. In this we follow the recommendation by De Mol, Giannone and Reichlin (2008) who study the case of Bayesian regressions. They show that with increasing size of the model one should shrink more to avoid overfitting, but when data are collinear one is still able to extract the relevant sample information. We apply this principle in the case of VARs. We compare the large model with smaller systems in terms of forecasting performance and structural analysis of the effect of monetary policy shock. The results show that a standard Bayesian VAR model is an appropriate tool for large panels of data once the degree of shrinkage is set in relation to the model size.
The fourth chapter entitled “Forecasting euro area inflation with wavelets: extracting information from real activity and money at different scales” proposes a framework for exploiting relationships between variables at different frequency bands in the context of forecasting. This work is motivated by the on-going debate whether money provides a reliable signal for the future price developments. The empirical evidence on the leading role of money for inflation in an out-of-sample forecast framework is not very strong, see e.g. Lenza (2006) or Fisher, Lenza, Pill and Reichlin (2008). At the same time, e.g. Gerlach (2003) or Assenmacher-Wesche and Gerlach (2007, 2008) argue that money and output could affect prices at different frequencies, however their analysis is performed in-sample. In this Chapter, it is investigated empirically which frequency bands and for which variables are the most relevant for the out-of-sample forecast of inflation when the information from prices, money and real activity is considered. To extract different frequency components from a series a wavelet transform is applied. It provides a simple and intuitive framework for band-pass filtering and allows a decomposition of series into different frequency bands. Its application in the multivariate out-of-sample forecast is novel in the literature. The results indicate that, indeed, different scales of money, prices and GDP can be relevant for the inflation forecast.
Doctorat en Sciences économiques et de gestion
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Coroneo, Laura. "Essays on modelling and forecasting financial time series". Doctoral thesis, Universite Libre de Bruxelles, 2009. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210284.
Texto completo da fonteThe first chapter investigates the distribution of high frequency financial returns, with special emphasis on the intraday seasonality. Using quantile regression, I show the expansions and shrinks of the probability law through the day for three years of 15 minutes sampled stock returns. Returns are more dispersed and less concentrated around the median at the hours near the opening and closing. I provide intraday value at risk assessments and I show how it adapts to changes of dispersion over the day. The tests performed on the out-of-sample forecasts of the value at risk show that the model is able to provide good risk assessments and to outperform standard Gaussian and Student’s t GARCH models.
The second chapter shows that macroeconomic indicators are helpful in forecasting the yield curve. I incorporate a large number of macroeconomic predictors within the Nelson and Siegel (1987) model for the yield curve, which can be cast in a common factor model representation. Rather than including macroeconomic variables as additional factors, I use them to extract the Nelson and Siegel factors. Estimation is performed by EM algorithm and Kalman filter using a data set composed by 17 yields and 118 macro variables. Results show that incorporating large macroeconomic information improves the accuracy of out-of-sample yield forecasts at medium and long horizons.
The third chapter statistically tests whether the Nelson and Siegel (1987) yield curve model is arbitrage-free. Theoretically, the Nelson-Siegel model does not ensure the absence of arbitrage opportunities. Still, central banks and public wealth managers rely heavily on it. Using a non-parametric resampling technique and zero-coupon yield curve data from the US market, I find that the no-arbitrage parameters are not statistically different from those obtained from the Nelson and Siegel model, at a 95 percent confidence level. I therefore conclude that the Nelson and Siegel yield curve model is compatible with arbitrage-freeness.
Doctorat en Sciences économiques et de gestion
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Romain, Astrid. "Essays in the empirical analysis of venture capital and entrepreneurship". Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210729.
Texto completo da fonteThis thesis aims at analysing some aspects of Venture Capital (VC) and high-tech entrepreneurship. The focus is both at the macroeconomic level, comparing venture capital from an international point of view and Technology-Based Small Firms (TBSF) at company and founder’s level in Belgium. The approach is mainly empirical.
This work is divided into two parts. The first part focuses on venture capital. First of all, we test the impact of VC on productivity. We then identify the determinants of VC and we test their impact on the relative level of VC for a panel of countries.
The second part concerns the technology-based small firms in Belgium. The objective is twofold. It first aims at creating a database on Belgian TBSF to better understand the importance of entrepreneurship. In order to do this, a national survey was developed and the statistical results were analysed. Secondly, it provides an analysis of the role of universities in the employment performance of TBSF.
A broad summary of each chapter is presented below.
PART 1: VENTURE CAPITAL
The Economic Impact of Venture Capital
The objective of this chapter is to perform an evaluation of the macroeconomic impact of venture capital. The main assumption is that VC can be considered as being similar in several respects to business R&D performed by large firms. We test whether VC contributes to economic growth through two main channels. The first one is innovation, characterized by the introduction of new products, processes or services on the market. The second one is the development of an absorptive capacity. These hypotheses are tested quantitatively with a production function model for a panel data set of 16 OECD countries from 1990 to 2001. The results show that the accumulation of VC is a significant factor contributing directly to Multi-Factor Productivity (MFP) growth. The social rate of return to VC is significantly higher than the social rate of return to business or public R&D. VC has also an indirect impact on MFP in the sense that it improves the output elasticity of R&D. An increased VC intensity makes it easier to absorb the knowledge generated by universities and firms, and therefore improves aggregate economic performance.
Technological Opportunity, Entrepreneurial Environment and Venture Capital Development
The objective of this chapter is to identify the main determinants of venture capital. We develop a theoretical model where three main types of factors affect the demand and supply of VC: macroeconomic conditions, technological opportunity, and the entrepreneurial environment. The model is evaluated with a panel dataset of 16 OECD countries over the period 1990-2000. The estimates show that VC intensity is pro-cyclical - it reacts positively and significantly to GDP growth. Interest rates affect the VC intensity mainly because the entrepreneurs create a demand for this type of funding. Indicators of technological opportunity such as the stock of knowledge and the number of triadic patents affect positively and significantly the relative level of VC. Labour market rigidities reduce the impact of the GDP growth rate and of the stock of knowledge, whereas a minimum level of entrepreneurship is required in order to have a positive effect of the available stock of knowledge on VC intensity.
PART 2: TECHNOLOGY-BASED SMALL FIRMS
Survey in Belgium
The first purpose of this chapter is to present the existing literature on the performance of companies. In order to get a quantitative insight into the entrepreneurial growth process, an original survey of TBSF in Belgium was launched in 2002. The second purpose is to describe the methodology of our national TBSF survey. This survey has two main merits. The first one lies in the quality of the information. Indeed, most of national and international surveys have been developed at firm-level. There exist only a few surveys at founder-level. In the TBSF database, information both at firm and at entrepreneur-level will be found.
The second merit is about the subject covered. TBSF survey tackles the financing of firms (availability of public funds, role of venture capitalists, availability of business angels,…), the framework conditions (e.g. the quality and availability of infrastructures and communication channels, the level of academic and public research, the patenting process,…) and, finally, the socio-cultural factors associated with the entrepreneurs and their environment (e.g. level of education, their parents’education, gender,…).
Statistical Evidence
The main characteristics of companies in our sample are that employment and profits net of taxation do not follow the same trend. Indeed, employment may decrease while results after taxes may stay constant. Only a few companies enjoy a growth in both employment and results after taxes between 1998 and 2003.
On the financing front, our findings suggest that internal finance in the form of personal funds, as well as the funds of family and friends are the primary source of capital to start-up a high-tech company in Belgium. Entrepreneurs rely on their own personal savings in 84 percent of the cases. Commercial bank loans are the secondary source of finance. This part of external financing (debt-finance) exceeds the combined angel funds and venture capital funds (equity-finance).
On the entrepreneur front, the preliminary results show that 80 percent of entrepreneurs in this study have a university degree while 42 percent hold postgraduate degrees (i.e. master’s, and doctorate). In term of research activities, 88 percent of the entrepreneurs holding a Ph.D. or a post-doctorate collaborate with Belgian higher education institutes. Moreover, more than 90 percent of these entrepreneurs are working in a university spin-off.
The Contribution of Universities to Employment Growth
The objective of this chapter is to test whether universities play a role amongst the determinants of employment growth in Belgian TBSF. The empirical model is based on our original survey of 87 Belgian TBSF. The results suggest that both academic spin-offs and TBSF created on the basis of an idea originating from business R&D activities are associated with an above than average growth in employees. As most ‘high-tech’ entrepreneurs are at least graduated from universities, there is no significant impact of the level of education. Nevertheless, these results must be taken with caution, as they are highly sensitive to the presence of outliers. Young high-tech firms are by definition highly volatile, and might be therefore difficult to understand.
CONCLUSION
In this last chapter, recommendations for policy-makers are drawn from the results of the thesis. The possible interventions of governments are classified according to whether they influence the demand or the supply of entrepreneurship and/or VC. We present some possible actions such as direct intervention in the VC funds, interventions of public sector through labour market rigidities, pension system, patent and research policy, level of entrepreneurial activities, bankruptcy legislation, entrepreneurial education, development of university spin-offs, and creation of a national database of TBSF.
Doctorat en Sciences économiques et de gestion
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Kazic, Dusan. "Plantes animées. De la production aux relations avec les plantes". Thesis, Université Paris-Saclay (ComUE), 2019. http://www.theses.fr/2019SACLA027.
Texto completo da fonteThis thesis deals with animated relationships between peasants and their plants in French fields. For some, plants are sentient and intelligent beings, for others they are working beings, accompanying beings, game beings, suffering beings. Some peasants speak to their plants, others weave loving relationships, and let their plants teach them how to cultivate them in the fields. In describing these relationships, the thesis shows that, thanks to the sensitive relations that these peasants weave with their plants, they animate them by leaving naturalist epistemologies aside. By taking these words seriously, literally, the thesis defends the hypothesis that, in order to prevent the agricultural world from becoming ruins, we must no longer seek to "produce differently", but we must break with the paradigm of production to anchor peasants and their plants in co-evolutionary relationships. By plunging into the history of modernity, that is to say by revisiting the conflict between the peasant world on one side and the modern world on the other, with the arrival of the physiocrats among the French intellectual and policy-making bodies, this thesis shows that the concept of production is based on a universalist and naturalized approach that has been imposed without any empirical basis in the agricultural world and in the modern world more widely
Toti, Boga Jean-François. "Rôle de l'éthique dans le processus de décision d'achat du consommateur et consommation éthique". Thesis, Aix-Marseille, 2015. http://www.theses.fr/2015AIXM2011.
Texto completo da fonteConsumption is part of the mechanisms that allow individuals to distinguish themselves, especially through culture, sports and food practices. Academics found that consumers express their ethics through their consumption choices. However, the definition of ethical consumption remains quite blurred in the field of consumer behavior and its measurement is not always appropriate. We propose in this research to clarify the concepts of consumer’s ethical sensibility (CES) and consumer’s ethical consumption behavior (ECB). Then, we build an appropriate conceptual framework to explore ethics in the field of consumption. First, a qualitative study was conducted with 14 in-depth interviews and then, in a second step, a quantitative data collection was conducted among 559 consumers. The results open interesting perspectives for academics and managers in the field of consumer ethics
Payen, Aurore. "Importance de la temporalité dans les phénomènes de propagation. Une illustration sur des échanges d'animaux d'élevage". Electronic Thesis or Diss., Sorbonne université, 2018. http://www.theses.fr/2018SORUS247.
Texto completo da fonteDisease spread among agricultural premises is greatly enhanced by cattle trade movements. Preventing spreading is a key issue for economical issues, for instance to prevent trade restrictions, but also for public health. Indeed, many animal diseases affect human beings, such as bovine tuberculosis. Tracing cattle trade movements is aiming at detecting the sources of infection, and thus, helps fighting against disease spread. Accessing databases recording cattle trade movements allows to study the structure and dynamic of the exchanges. To do so, methods developed for Social Network Analysis are more and more adapted and use for these purposes. The aim of this work is to use temporal models and methods to study cattle trade movements. As the development of temporal networks is relatively recent, few analyzes using these methods have been conduct on cattle trade data. Thus, contributions are twofold in this work: taking part to the development of analysis tools of temporal networks, and then, deducting potential ways of enhancement to control and fight against disease spread among holdings
Largeron, Yann. "Dynamique de la couche limite atmosphérique stable en relief complexe : application aux épisodes de pollution particulaire des vallées alpines". Phd thesis, Grenoble, 2010. http://www.theses.fr/2010GRENU032.
Texto completo da fonteThe study is focusing on the dynamics of the stably-stratified Atmospheric Boundary Layer in wintertime in valleys, especially during situations leading to PM10 pollution peaks. The analysis is made by means of LES-like numerical simulations and local measurements. In a first part, we study the katabatic wind created over the slopes of a narrow valley. We show that they are intermittent and turbulent and that their turbulent diffusivity is proportional to the square of a Froude number, and decreases with the ambient stratification. We also study the internal wave field generated by these winds and find that this frequency depends only on the stratification and seems to be independent of the characteristics of its source. In a second part, we study the valley wind system and the thermal inversions which occur by winter conditions in the valleys of the Grenoble area. Meteorological conditions leading to pollution episodes in the Grenoble valleys are also studied and their link with the previous mechanisms are explained. We show that these episodes take place during anticyclonic conditions, are induced by thermal inversion and that their evolution is linked to that of the weather regimes. During these episodes, we show that the local winds system is always the same, independent of the synoptical regime and consists of thermally-driven winds, whose spatial organization is controlled by the geometry of the site. These currents are confined into a thermal inversion, which persists during the whole episode, and is however not destroyed during the day if the solar energy is not sufficient. The corresponding energy treshold is highlighted
Hites, Gisèle. "Essays on the dynamics of cross-country income distribution and intra-household time allocation". Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210601.
Texto completo da fonteThe first part is methodological and macroeconomic in nature, addressing the question of whether the distribution of income across countries is converging (i.e. are the poor catching up to the rich?) or diverging (i.e. are we witnessing the formation of two exclusive clubs, one for poor countries and another one for rich countries?). Applications of the simple Markov model to this question have generated evidence in favor of the divergence hypothesis. In the first chapter, I critically review these results. I use statistical inference to show that the divergence results are not statistically robust, and I explain that this instability of the results comes from the application of a model for discrete data to data that is actually continuous. In the second chapter, I reposition the whole convergence-divergence debate by placing it in the context of Silverman’s classic survey of non-parametric density estimation techniques. This allows me to use the basic notions of fuzzy logic to adapt the simple Markov chain model to continuous data. When I apply the newly adapted Markov chain model to the cross-country distribution question, I find evidence against the divergence hypothesis, and this evidence is statistically robust.
The second part of the thesis is empirical and microeconomic in nature. I question whether observed differences between husbands’ and wives’ participation in labor markets are due to different preferences or to different constraints. My identification strategy is based on the idea that the more power an individual has relative to his/her partner, the more his/her actions will reflect his/her preferences. I use 2001 PSID data on cohabiting couples to estimate a simultaneous equations model of the spousal time allocation decision. My results confirm the stylized fact that specialization and trade does not explain time allocation for couples in which the wife is the primary breadwinner, and suggest that power could provide a more general explanation of the observations. My results show that wives with relatively more power choose to work more on the labor market and less at home, whereas husbands with more power choose to do the opposite. Since women start out from a lower level of labor market participation than men do, it would seem that spouses’ agree that the ideal mix of market work and housework lies somewhere between the husbands’ and the wives’ current positions.
Doctorat en sciences économiques, Orientation économie
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Cincera, Michele. "Economic and technological performances of international firms". Doctoral thesis, Universite Libre de Bruxelles, 1998. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/212081.
Texto completo da fonteThe second chapter illustrates the importance of R&D investments, patenting activities and other measures of technological activities performed by firms over the last 10 years.
The third chapter describes the main features as well as the construction of the database. The raw data sample consists of comparable detailed micro-level data on 2676 large manufacturing firms from several countries. These firms have reported important R&D expenditures over the period 1980-1994.
The fourth chapter explores the dynamic structure of the patent-R&D relationship by considering the number of patent applications as a function of present and lagged levels of R&D expenditures. R&D spillovers as well as technological and geographical opportunities are taken into account as additional determinants in order to explain patenting behaviours. The estimates are based on recently developed econometric techniques that deal with the discrete non-negative nature of the dependent patent variable as well as the simultaneity that can arise between the R&D decisions and patenting. The results show evidence of a rather contemporaneous impact of R&D activities on patenting. As far as R&D spillovers are concerned, these externalities have a significantly higher impact on patenting than own R&D. Furthermore, these effects appear to take more time, three years on average, to show up in patents.
The fifth chapter explores the contribution of own stock of R&D capital to productivity performance of firms. To this end the usual productivity residual methodology is implemented. The empirical section presents a first set of results which replicate the analysis of previous studies and tries to assess the robustness of the findings with regard to the above issues. Then, further results, based on different sub samples of the data set, investigate to what extent the R&D contribution on productivity differs across firms of different industries and geographic areas or between small and large firms and low and high-tech firms. The last section explores more carefully the simultaneity issue. On the whole, the estimates indicate that R&D has a positive impact on productivity performances. Yet, this contribution is far from being homogeneous across the different dimensions of data or according to the various assumptions retained in the productivity model.
The last empirical chapter goes deeper into the analysis of firms' productivity increases, by considering besides own R&D activities the impact of technological spillovers. The chapter begins by surveying the alternative ways proposed in the literature in order to asses the effect of R&D spillovers on productivity. The main findings reported by some studies at the micro level are then outlined. Then, the framework to formalize technological externalities and other technological determinants is exposed. This framework is based on a positioning of firms into a technological space using their patent distribution across technological fields. The question of whether the externalities generated by the technological and geographic neighbours are different on the recipient's productivity is also addressed by splitting the spillover variable into a local and national component. Then, alternative measures of technological proximity are examined. Some interesting observations emerge from the empirical results. First, the impact of spillovers on productivity increases is positive and much more important than the contribution of own R&D. Second, spillover effects are not the same according to whether they emanate from firms specialized in similar technological fields or firms more distant in the technological space. Finally, the magnitude and direction of these effects are radically different within and between the pillars of the Triad. While European firms do not appear to particularly benefit from both national and international sources of spillovers, US firms are mainly receptive to their national stock and Japanese firms take advantage from the international stock.
Doctorat en sciences économiques, Orientation économie
info:eu-repo/semantics/nonPublished
Louati, Amine. "Une approche multi-agents pour la composition de services Web fondée sur la confiance et les réseaux sociaux". Thesis, Paris 9, 2015. http://www.theses.fr/2015PA090035/document.
Texto completo da fonteThis thesis deals with service discovery, selection and composition problems. The aim is to fulfill a complex requester query. To do that, we propose a multi-agent approach based on trust and social networks. We define a trust model as a compositional concept that includes social, expert, recommender and cooperation-based component. The social-based component judges whether or not the provider is worthwhile pursuing before using his services. The expert-based component estimates whether or not the service behaves well and as expected. The recommender-based component checks whether or not an agent is reliable and if we can rely on its recommendations. The cooperation-based component allows agents to decide with whom to interact in a service composition. We propose a distributed algorithm for service discovery using trust between agents and referral systems in social networks. We also develop a new method based on a probabilistic model to infer trust between non adjacent agents while taking into account roles of intermediate agents. Finally, we present an original coalition formation process which is incremental, dynamic and overlapping for service composition in social networks. %In particular, our coalition formation process engaging self-interested agents is incremental, dynamic and overlapping. Experimental results show that our multi-agents approaches are efficient, outperforms existing similar ones and can deliver more trustworthy results at low cost of communications