Consistency of Bayesian procedures for variable selection

It has long been known that for the comparison of pairwise nested models, a decision based on the Bayes factor produces a consistent model selector (in the frequentist sense). Here we go beyond the usual consistency for nested pairwise models, and show that for a wide class of prior distributions, including intrinsic priors, the corresponding Bayesian procedure for variable selection in normal regression is consistent in the entire class of normal linear models. We find that the asymptotics of the Bayes factors for intrinsic priors are equivalent to those of the Schwarz (BIC) criterion. Also, recall that the Jeffreys--Lindley paradox refers to the well-known fact that a point null hypothesis on the normal mean parameter is always accepted when the variance of the conjugate prior goes to infinity. This implies that some limiting forms of proper prior distributions are not necessarily suitable for testing problems. Intrinsic priors are limits of proper prior distributions, and for finite sample sizes they have been proved to behave extremely well for variable selection in regression; a consequence of our results is that for intrinsic priors Lindley's paradox does not arise.Comment: Published in at http://dx.doi.org/10.1214/08-AOS606 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Investigación iberoamericana sobre enseñanza eficaz

La investigación sobre Enseñanza efi caz es quizá la línea de análisis que más ha ayudado a la mejora de la calidad de la educación. Los objetivos de este trabajo son identifi car los factores que hacen que una enseñanza sea efi caz y determinar cuál es el impacto de cada uno de ellos, así como elaborar un modelo iberoamericano de Enseñanza efi caz. Se utilizan análisis multinivel con cuatro niveles, con cuatro variables de producto, dos de desarrollo cognitivo (rendimiento en lengua y rendimiento en matemáticas) y dos de socio-afectivo (autoconcepto y satisfacción hacia la escuela), y considera el rendimiento previo del alumno. Se analiza la información de 5 mil 722 estudiantes de nueve países de Iberoamérica. Finalmente, se comprueba la existencia de diez factores de Enseñanza eficazResearch on eff ective teaching is perhaps the line of analysis that has most improved the quality of education. The objectives of this article are to identify the factors that make teaching eff ective and to determine the impact of each factor, as well as to elaborate an Ibero-American model of eff ective teaching. Multilevel analysis with four levels is used, with four product variables: two in cognitive development (achievement in language and achievement in mathematics) and two in social-aff ectivity (self-concept and satisfaction at school), considering the student’s previous achievement. An analysis is made of information regarding 5,722 students in nine Ibero-American countries. The existence of ten factors of eff ective teaching is prove

The effect of the non-instructional time of teachers on cognitive development of students in Iberoamerica

El objetivo de la investigación es determinar la incidencia del porcentaje de tiempo que los docentes iberoamericanos de Educación Primaria destinan tareas no lectivas sobre el logro académico de sus estudiantes en Matemáticas y en Lectura. Para alcanzar dicho objetivo se han utilizado Modelos Multinivel de cuatro niveles de análisis (estudiante, aula, escuela y país) para el análisis de la información de la distribución del tiempo de 256 docentes de 9 países de Iberoamérica y sus 5.610 estudiantes. Los resultados encontrados señalan que una mayor dedicación a tres tareas mejora significativamente el logro de los estudiantes: la preparación de las clases, la corrección de evaluaciones y el trabajo con familias. Y, por el contrario, una mayor dedicación a tareas administrativas hace que disminuya el logro de los estudiantes. Con estos resultados se aportan evidencias empíricas acerca de la necesidad de que los docentes tengan unas condiciones laborales adecuadas para desempeñar adecuadamente su trabajoThis research aims to determine the incidence of the percentage of time that Latin American teachers of Primary Education allocated to different no teaching related tasks on the academic achievement of students in Mathematics and Language. To reach this aim we use multilevel models with four levels of analysis (student, classroom, school and country) to analyzed the information about teachers’ distribution time of 256 teachers from 9 countries in Latin America and 5,610 students. Our results show that an increased focus on three tasks significantly improves student achievement: the lesson preparation, correction of assessments, and work with families. And, conversely, a greater emphasis on administrative tasks lowers achieving students. With these results, empirical evidence is provided on the need for teachers to have suitable working conditions to adequately perform their job

Understanding the impact of line-of-sight in the ergodic spectral efficiency of cellular networks

In this paper we investigate the impact of lineof-sight (LoS) condition in the ergodic spectral efficiency of cellular networks. To achieve this goal, we have considered the kappa-mu shadowed model, which is a general model that provides an excellent fit to a wide set of propagation conditions. To overcome the mathematical complexity of the analysis, we have split the analysis between large and small-scale effects. Building on the proposed framework, we study a number of scenarios that range from heavily-fluctuating LoS to deterministic-LoS. Finally, we shed light on the interplay between fading severity and spectral efficiency by means of the amount of fading.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A hybrid approach for directory facilitators in a FIPA multi-agent platform

In this work we present a research line that focus on the design and implementation of a Directory Facilitator for a FIPA multi-agent platform. We will introduce three different approaches: a centralized version, a distributed one, and a hybrid solution. As we will explain below, the hybrid approach will have several advantages and it will be our choice for future implementations.Eje: Inteligencia artificialRed de Universidades con Carreras en Informática (RedUNCI

Comprender y construir la mediación intercultural = Understanding and developing the intercultural mediation

Ante la relativamente nueva introducción de la denominada mediación intercultural en el escenario del trabajo con la inmigración extranjera en España, se han multiplicado los debates y posiciones sobre la figura profesional que ha de ejercer tal actividad de mediación intercultural. Para contribuir a dichos debates aportamos el resumen de los resultados de un estudio que pretende delimitar el perfil del llamado "mediador o mediadora intercultural". El estudio ha consistido básicamente en hacer un recorrido por tres fuentes de información fundamentales: la formación que se ha proporcionado a mediadores y mediadoras interculturales en diferentes contextos europeos, las características y competencias que se les han atribuido y, por último, las funciones que se dice debe cumplir la mediación. Estos tres ámbitos de información deben dar respuesta adecuada al perfil del mediador o mediadora intercultural, destacando en especial su delimitación profesional, las proximidades y relaciones con otras profesiones y, en especial, el tipo de formación necesario para la capacitación profesional.In the face of the relatively new introduction of the named intercultural mediation in the context of work with foreign immigration in Spain, debates and positions on the professional figure that intercultural mediation has to be wielded have multiplied. In order to contribute to such debates, we provide the summary of the results of a study that aims to delimit the profile of the so called ‘’intercultural mediator’’. The study basically consisted of taking a tour for three fundamental sources of information: The training provided to intercultural mediators in different European contexts, the characteristics and competences attributed to them, and lastly, the functions that are said to be fulfilled by the mediator. These three aspects of information must give an adequate answer to the ’intercultural mediator’ profile, highlighting his professional delimitations, the proximities and relations with other professions, and especially, the type of training required for the vocational training

Gestión óptima de aguas subterráneas : regulación frente a no regulación

En este artículo se comparan dos modelos de gestión de aguas subterráneas: control y no-control. La diferencia entre ambos viene dada porque en el primero de ellos se computa el coste de uso del recurso, mientras que en el segundo no. La demanda de agua subterránea se desagrega por cultivos lo que permite obtener una asignación inter e intratemporal del recurso. Asimismo se realiza la aplicación sobre el acuífero de Ascoy-Sopalmo (Cuenca del Segura). La obtención del valor presente del excedente neto de los agricultores en ambos escenarios permite concluir que la pérdida de eficiencia es mínima para unos valores normales de las tasas de descuento y recarga.In this paper two management models of groundwater (control and no-control) are compared. The difference between these models is that in the first one user cost is considered whilst in the second one is not. The groundwater demand is disaggregated by crops, which makes possible to obtain an inter and intratemporal resource allocation. Furthermore, an application to the aquifer of Ascoy-Sopalmo (Segura Basin) is carried out. From the present value of the farmer's net surplus, derived in both models, we can conclude that the efficiency loss is minimum for normal values of the discount rate and recharge rate

School segregation by national origin in Spain

Esta investigación busca estimar la magnitud de la segregación escolar por origen nacional en España y sus Comunidades Autónomas en Educación Secundaria Obligatoria y contrastar estos resultados con los de los países de la Unión Europea. Para ello, se realiza una explotación especial de los datos PISA-2015 estimando el índice de Gorard. Los resultados indican que la magnitud de la segregación escolar por origen nacional en España es 0,45 (por debajo de la media europea). Sin embargo, los valores de la segregación neta reflejan una imagen menos optimista, de ser el tercer país con menos segregación de la Unión Europea, pasa a ser el séptimo.The aims of this research are to estimate the magnitude of school segregation by national origin in compulsory secondary education in Spain and its Autonomous Communities, and to compare with the results from other countries in the European Union. In order to achieve those aims, we used the PISA-2015 database and estimate the Gorard index. Our results indicate that the magnitude of school segregation by national origin in Spain is 0.45 (below the European average). However, net segregation values reflect a less optimistic image for Spain, from the third country with the least segregation of the European Union, becomes the seventh.Este artículo ha sido desarrollado en el marco del Proyecto I+D+i de Excelencia “Escuelas en contextos socio-económicamente desafiantes: Una aproximación desde la Educación para la Justicia Social” Ref: EDU2014-56118-P. Financiado con fondos del Ministerio de Economía y Competitividad-Gobierno de España

Capacity Limits of Spectrum-Sharing in Hoyt (Nakagami-q) Fading Channels

A channel capacity analysis is presented in this work for a spectrum-sharing cognitive radio link in which the fading experienced by the signal is modeled with the Hoyt (Nakagami-q) distribution. Based on a novel formulation of the squared Hoyt distribution derived by the authors, simple expressions for the capacity of the secondary link in a number of scenarios of interest are derived, which are given in terms of easy-to-compute finite-range integrals of elementary functions. The effect of fading severity in the secondary transmitter-primary receiver (ST-PR) and secondary transmitter-secondary receiver (ST-SR) links, and the impact of different antenna gains on the system performance are analyzed. We show that in the presence of severe fading for the ST-PR link, the capacity of the ST-SR link is increased.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. MINECO. Fondos FEDER. European Union Marie-Curie COFUND U-mobility program