Rejoinder: Bayesian Checking of the Second Levels of Hierarchical Models

Rejoinder: Bayesian Checking of the Second Levels of Hierarchical Models [arXiv:0802.0743]Comment: Published in at http://dx.doi.org/10.1214/07-STS235REJ the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Objective Bayes testing of Poisson versus inflated Poisson models

The Poisson distribution is often used as a standard model for count data. Quite often, however, such data sets are not well fit by a Poisson model because they have more zeros than are compatible with this model. For these situations, a zero-inflated Poisson (ZIP) distribution is often proposed. This article addresses testing a Poisson versus a ZIP model, using Bayesian methodology based on suitable objective priors. Specific choices of objective priors are justified and their properties investigated. The methodology is extended to include covariates in regression models. Several applications are given.Comment: Published in at http://dx.doi.org/10.1214/074921708000000093 the IMS Collections (http://www.imstat.org/publications/imscollections.htm) by the Institute of Mathematical Statistics (http://www.imstat.org

Criteria for Bayesian model choice with application to variable selection

In objective Bayesian model selection, no single criterion has emerged as dominant in defining objective prior distributions. Indeed, many criteria have been separately proposed and utilized to propose differing prior choices. We first formalize the most general and compelling of the various criteria that have been suggested, together with a new criterion. We then illustrate the potential of these criteria in determining objective model selection priors by considering their application to the problem of variable selection in normal linear models. This results in a new model selection objective prior with a number of compelling properties.Comment: Published in at http://dx.doi.org/10.1214/12-AOS1013 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

Bayesian design and analysis of replications in scientific experimentation

En la práctica estadística es frecuente la replicación de experiencias estadísticas, justificada por muy diversos intereses: ratificar conclusiones, estudiar la variación en las respuestas cuando se experimenta sobre una población distinta, validar un modelo, detectar sesgos, etc. Al disponer, antes de replicar, de los resultados de cierto estudio previo, es razonable pensar en buscar un buen diseño para la réplica utilizando la información que dicho primer estudio proporciona. Un diseño óptimo de la réplica consistirá en decidir, asumido un modelo, sobre el menor tamaño muestral que otorga al investigador suficientes garantías de concluir con éxito en su inferencia. Una modelización jerárquica bayesiana permite precisar fácilmente las relaciones entre datos y poblaciones (original y replicada) y derivar conclusiones sobre los resultados más probables (en función del tamaño de la réplica) a través de las distribuciones a posteriori y predictivas que se obtengan

On the prevalence of information inconsistency in normal linear models

Informally, ‘information inconsistency’ is the property that has been observed in some Bayesian hypothesis testing and model selection scenarios whereby the Bayesian conclusion does not become definitive when the data seem to become definitive. An example is that, when performing a t test using standard conjugate priors, the Bayes factor of the alternative hypothesis to the null hypothesis remains bounded as the t statistic grows to infinity. The goal of this paper is to thoroughly investigate information inconsistency in various Bayesian testing problems. We consider precise hypothesis tests, one-sided hypothesis tests, and multiple hypothesis tests under normal linear models with dependent observations. Standard priors are considered, such as conjugate and semi-conjugate priors, as well as variations of Zellner’s g prior (e.g., fixed g priors, mixtures of g priors, and adaptive (data-based) g priors). It is shown that information inconsistency is a widespread problem using standard priors while certain theoretically recommended priors, including scale mixtures of conjugate priors and adaptive priors, are information consistent

Comparative evaluation of impedanciometry combined with chromogenic agars or RNA hybridization and real-time PCR methods for the detection of L. monocytogenes in dry-cured ham

Listeria monocytogenes is an important foodborne pathogen of particular relevance in “Ready To Eat” products. Food producers require rapid methods to detect L. monocytogenes, since the reference method (ISO 11290-1) is laborious, lengthy and costly. The aim of this study was to evaluate three alternative methods to detect L. monocytogenes in dry-cured ham following the ISO 16140-2:2016 standard: (A) impedance measurement followed by plating onto chromogenic agars; (B) impedance measurement followed by RNA hybridization, and (C) real-time PCR. Inclusivity and exclusivity were evaluated. The limits of detection 50 (LOD50) and the relative limits of detection (RLOD) were obtained by analysing dry-cured ham samples inoculated with L. monocytogenes at three different levels of contamination. The sensitivity study of alternative methods, as well as the relative specificity (SP), sensitivity (SE), and Kappa Cohen''s index were calculated analysing 93 samples of sliced dry-cured ham. The inclusivity and exclusivity tests of three methods showed no interference in pathogen detection. LOD50 were very low for the three methods evaluated (<1 cfu/25 g dry-cured ham). The RLOD values of the three alternative methods were below the acceptability limit established by ISO 16140. For methods A and C, good results were obtained in the sensitivity study, as well as in the SP and SE. However, method B showed poorer results in the sensitivity study, along with lower results for SP (99.7%) and SE (79.6%), due to the occurrence of false positives and negatives in samples with presence of other Listeria spp. Methods A and C were considered to be a thoroughly appropriate control tool for use in the meat industry to improve the detection of L. monocytogenes

Un texto espiritual del siglo XVI

El texto espiritual al que nos referimos es una traducción al italiano del Segundo Abecedario Espiritual de Francisco de Osuna, realizada por el padre dominico Timoteo Bottonio a finales del siglo XVI. Quisiéramos advertir que si bien en este caso nos limitaremos a estudiar única y exclusivamente la traducción del Segundo Abecedario, ésta forma parte de un proyecto de investigación mucho más amplio y no es un hecho aislado. No debemos olvidar que existía una importante corriente de intercambio espiritual entre España e Italia durante el siglo XV