The Simple Economics of Hog Marketing Reforms in Quebec

Hogs, marketing, vertical coordination, auctions, Industrial Organization, Livestock Production/Industries, Marketing,

Moment-based density and risk estimation from grouped summary statistics

Data on a continuous variable are often summarized by means of histograms or displayed in tabular format: the range of data is partitioned into consecutive interval classes and the number of observations falling within each class is provided to the analyst. Computations can then be carried in a nonparametric way by assuming a uniform distribution of the variable within each partitioning class, by concentrating all the observed values in the center, or by spreading them to the extremities. Smoothing methods can also be applied to estimate the underlying density or a parametric model can be fitted to these grouped data. For insurance loss data, some additional information is often provided about the observed values contained in each class, typically class-specific sample moments such as the mean, the variance or even the skewness and the kurtosis. The question is then how to include this additional information in the estimation procedure. The present paper proposes a method for performing density and quantile estimation based on such augmented information with an illustration on car insurance data

Remittances and poverty : Who benefits in the household ?.

We use data from a newly designed household survey in Senegal to study intrahousehold allocation of remittances income. In this survey, households are split between sub-groups of individuals, in a way that is natural to households and that corresponds to the internal budgetary arrangements found in the extended families of Senegal. We find that remittances accruing to specific individuals in the household are not completely fungible with other sources of income. In particular the school enrolment of children aged 7 to 13 is found to depend on remittances income accruing to the sub-group he/she belongs to and not on the remittances accruing to other sub-groups. Looking at total expenditures, we also find that transfers received by a sub-group are a significant determinant of its own consumption, contrarily to transfers received by other groups. This is not true for food consumption, suggesting that households tend to satisfy the basic needs of all their members.Économie domestique; Indicateurs de pauvreté; Envois de fonds; Revenu discrétionnaire; Senegal;

Vers le "Design d'information" pour valoriser les résultats d'une veille sur les maladies chroniques

National audienceThe topics of this research work cover all phases of the “Information Design” applied to the “chronic disease” since the analysis requirements to the achievement of the deliverable, as an information system for the decision support. As defined, the field of information design applies the process of translating complex, unorganized, or unstructured data into valuable and meaningful information. Its practice requires an interdisciplinary approach which combines skills in graphic design –writing, analysis processing and editing-, human performance technology and human factors. In our approach to implement the "information design", the processes used and relied cover the whole of this theme implicitly while we develop the KM process in the context of the Economic Intelligence. In this paper, at first, we consider the used approach to extract knowledge, as noun phrase (or NP) concepts, from a database bibliographic references that we formed for scientific monitoring. In this approach, Sahbi Sidhom in his Ph.D. thesis built a morpho-syntactic analysis platform for automatic indexing and information retrieval (IR), using syntactic graphs to extract NPs from corpus. This approach is applied to French and American bibliographic databases in a multilingual monitoring view. At second, through natural language processing (NLP), the concepts extracted (NPs and semantic relations) from bibliographic corpus are visualized with semantic graphs. At last, we discuss the results based on corpus processing and the connection to multilingual concepts in monitoring process. What is looked at this last work can start with new topic, the “intercultural intelligence” for information monitoring. Index Terms — Natural Language Processing, Data Visualization, Information Indexing, Knowledge Management (KM), Economic Intelligence, Noun Phrase concept, Semantic Graph, Intercultural Intelligence, Information DesignL'objectif du travail est de concevoir un système d'aide à la décision (SIAD) associant une série de problèmes à résoudre liée à la gestion de l'information. En premier, comment adapter l'espace collaboratif que représente le SIAD à un groupe de travail, composé d'experts issus de différentes spécialités médicales (psychologues, épidémiologistes, gastro-entérologues, etc.) ? Comment traiter l'hétérogénéité des sources pour assurer une intégration au SIAD permettant par la suite un traitement efficace de l'information ? Enfin, comment l'usager (i.e. l'expert) peut-il tirer bénéfice de la masse d'informations contenue dans le système ? La première partie de cet article présente la méthodologie et les outils mis en œuvre dans le cadre d'une veille informationnelle. Si le SIAD comporte des formats de documents diverses, l'échantillon test de notre méthodologie a concerné un corpus de notices issues de différentes bases de données bibliographiques. L'implémentation pour ce travail a nécessité l'élaboration d'un outil spécifique à notre thématique. La deuxième partie fait état des résultats obtenus après l'analyse automatique des notices bibliographiques avec leur rendu visuel pour l'émergence de nouvelles connaissances. Enfin, la dernière partie est consacrée à la discussion de ces résultats d'analyse et des nouvelles connaissances

Robust specification of the roughness penalty prior distribution in spatially adaptive Bayesian P-splines models

peer reviewedThe potential important role of the prior distribution of the roughness penalty parameter in the resulting smoothness of Bayesian Psplines models is considered. The recommended specification for that distribution yields models that can lack flexibility in specific circumstances. In such instances, these are shown to correspond to a frequentist P-splines model with a predefined and severe roughness penalty parameter, an obviously undesirable feature. It is shown that the specification of a hyperprior distribution for one parameter of that prior distribution provides the desired flexibility. Alternatively, a mixture prior can also be used. An extension of these two models by enabling adaptive penalties is provided. The posterior of all the proposed models can be quickly explored using the convenient Gibbs sampler.IAP research network nr P5/2

Penalty parameter selection and asymmetry corrections to Laplace approximations in Bayesian P-splines models

Laplacian-P-splines (LPS) associate the P-splines smoother and the Laplace approximation in a unifying framework for fast and flexible inference under the Bayesian paradigm. Gaussian Markov field priors imposed on penalized latent variables and the Bernstein-von Mises theorem typically ensure a razor-sharp accuracy of the Laplace approximation to the posterior distribution of these variables. This accuracy can be seriously compromised for some unpenalized parameters, especially when the information synthesized by the prior and the likelihood is sparse. We propose a refined version of the LPS methodology by splitting the latent space in two subsets. The first set involves latent variables for which the joint posterior distribution is approached from a non-Gaussian perspective with an approximation scheme that is particularly well tailored to capture asymmetric patterns, while the posterior distribution for parameters in the complementary latent set undergoes a traditional treatment with Laplace approximations. As such, the dichotomization of the latent space provides the necessary structure for a separate treatment of model parameters, yielding improved estimation accuracy as compared to a setting where posterior quantities are uniformly handled with Laplace. In addition, the proposed enriched version of LPS remains entirely sampling-free, so that it operates at a computing speed that is far from reach to any existing Markov chain Monte Carlo approach. The methodology is illustrated on the additive proportional odds model with an application on ordinal survey data

Integrated bi-directional SiC MOSFET power switches for efficient, power dense and reliable matrix converter assembly

This paper presents an innovative device packaging and system integration approach aimed at optimizing the electro-thermal, electro-magnetic and thermo-mechanical performance of the switches in a power converter. In particular, the focus is on state-of-the-art commercially available silicon-carbide (SiC) power MOSFETs used within a matrix converter topology. The improvements at switch level over conventional packaging and integration solutions translate into higher efficiency, power density (in terms of volume and weight) and reliability at system level. In view of typical application domains (e.g., renewable energies, solid-state transformation, smart grids, electric transport), requiring harsh environment withstand capability with high reliability and availability levels, an AC-to-AC matrix converter is chosen as a particularly relevant case study. The paper also addresses two aspects of growing relevance: reliable manufacturability and preventive maintenance compatible modular system assembly for reduced impact of single component failure on system availability

An approach for Fault Tolerant and Performance Guarantee Autonomous Robotic Mission

International audienceLong duration autonomous missions are still challenging objectives for robotics. This paper presents a new methodology using performance points of view to guide hardware and software resources management according to mission execution and fault occurrence. Experimental results on a patrolling mission are presented. It also detail how localization guarantee is managed and what impact it has on the overall methodology and its performances