Search results for "Bay"
showing 10 items of 1187 documents
Bayesian temporal and spatio-temporal Markov switching models for the detection of influenza outbreaks
2017
Influenza is a disease which affects millions of people every year and causes hundreds of thousends of deads every year. This disease causes substantial direct and indirect costs every year. The influenza epidemic have a particular behavior which shapes the statistical methods for their detection. Seasonal epidemics happen virtually every year in the temperate parts of the globe during the cold months and extend throughout whole regions, countries and even continents. Besides the seasonal epidemics, some nonseasonal epidemics can be observed at unexpected times, usually caused by strains which jump the barrier between animals and humans, as happened with the well known Swine Flu epidemic, w…
Production and Efficiency in 21 Industrialized Countries from 1966 to 2007 to Analyse the Italy’s Decline: Application of a Stochastic Frontier Model…
2008
This paper uses a stochastic frontier production model to estimate the technical efficiency of 21 nations among the more industrialized countries in the world for the wide period from 1966 to 2007. A Cobb-Douglas with labour and capital as inputs, GDP as output and efficiency with exponential distribution appears to work good from a statistical point of view. This model is used to estimate in a bayesian approach the efficiency score of these 21 countries. The bayesian way, applied via Gibbs sampling, is here useful to avoid problems about the small number of observations. So, each efficiency score is obtained as mean of 10,000 draws. The results underline a general and progressive efficienc…
The Spatial Overlap of Police Calls Reporting Street-Level and Behind-Closed-Doors Crime: A Bayesian Modeling Approach
2021
Traditionally, intimate-partner violence has been considered a special type of crime that occurs behind closed doors, with different characteristics from street-level crime. The aim of this study is to analyze the spatial overlap of police calls reporting street-level and behind-closed-doors crime. We analyzed geocoded police calls in the 552 census-block groups of the city of Valencia, Spain, related to street-level crime (N = 26,624) and to intimate-partner violence against women (N = 11,673). A Bayesian joint model was run to analyze the spatial overlap. In addition, two Bayesian hierarchical models controlled for different neighborhood characteristics to analyze the relative risks. Resu…
Generalizability and Simplicity as Criteria in Feature Selection: Application to Mood Classification in Music
2011
Classification of musical audio signals according to expressed mood or emotion has evident applications to content-based music retrieval in large databases. Wrapper selection is a dimension reduction method that has been proposed for improving classification performance. However, the technique is prone to lead to overfitting of the training data, which decreases the generalizability of the obtained results. We claim that previous attempts to apply wrapper selection in the field of music information retrieval (MIR) have led to disputable conclusions about the used methods due to inadequate analysis frameworks, indicative of overfitting, and biased results. This paper presents a framework bas…
Late Quaternary marine ostracods of the Basque Basin (S Bay of Biscay): taxonomy and distribution
2018
Late Quaternary taxonomy and ecologic and age distributions of ostracods from the Basque Basin (S Bay of Biscay) are described. More than forty-four thousands ostracod specimens have been obtained from one hundred surface samples and core samples from six cores located in shelf and upper bathyal depths and other infrabathyal core as comparative deep reference. A total of 155 species have been taxonomically described, belonging to 67 genera. Most characteristic species (123) have been SEM figured, and ecologic-geographic distributions and ages have been provided for all species. The resulting database will be a useful help for palaeoceanographic and palaeoclimatologic studies of the region.
La falta de reproducibilitat de la investigació: L'estadística com a legitimació del resultat
2014
La investigació científica es legitima mitjançant la replicació dels seus resultats, però els esforços per replicar afirmacions enganyoses exhaureixen el finançament. Ens centrarem en una d’aquestes errades: els resultats de proves estadístiques que ofereixen falsos positius a causa de l’atzar. Els mètodes estadístics clàssics confien en un p-valor per a ponderar les proves enfront d’una hipòtesi nul·la, però les proves d’hipòtesis bayesianes ofereixen resultats més fàcils de comprendre, sempre que hom puga especificar distribucions a priori per a la hipòtesi alternativa. Descriurem noves proves, les UMPBT, tests bayesians que ofereixen una especificació per defecte de les alternatives a pr…
Improving statistical classification methods and ecological status assessment for river macroinvertebrates
2016
Aquatic ecosystems are facing a growing number of human-induced stressors and the need to implement more biomonitoring to assess the ecological status of water bodies is eminent. This dissertation aims at providing tools to reduce the costs and improve the accuracy of freshwater benthic macroinvertebrate biomonitoring. To improve the cost-e ciency, we consider automated classi cation and develop a novel classi er suitable for complex macroinvertebrate image data. To enhance the accuracy of macroinvertebrate biomonitoring, we study the statistical properties of the Percent Model A nity index crucial to current Finnish biomonitoring and the factors a ecting these statistics. Finally, we perfo…
Single-cell analysis of population context advances RNAi screening at multiple levels
2012
Isogenic cells in culture show strong variability, which arises from dynamic adaptations to the microenvironment of individual cells. Here we study the influence of the cell population context, which determines a single cell's microenvironment, in image‐based RNAi screens. We developed a comprehensive computational approach that employs Bayesian and multivariate methods at the single‐cell level. We applied these methods to 45 RNA interference screens of various sizes, including 7 druggable genome and 2 genome‐wide screens, analysing 17 different mammalian virus infections and four related cell physiological processes. Analysing cell‐based screens at this depth reveals widespread RNAi‐induce…
Theoretical and methodological aspects of MCMC computations with noisy likelihoods
2018
Approximate Bayesian computation (ABC) [11, 42] is a popular method for Bayesian inference involving an intractable, or expensive to evaluate, likelihood function but where simulation from the model is easy. The method consists of defining an alternative likelihood function which is also in general intractable but naturally lends itself to pseudo-marginal computations [5], hence making the approach of practical interest. The aim of this chapter is to show the connections of ABC Markov chain Monte Carlo with pseudo-marginal algorithms, review their existing theoretical results, and discuss how these can inform practice and hopefully lead to fruitful methodological developments. peerReviewed
Statistical modelling of selective non-participation in health examination surveys
2018
Health examination surveys aim to collect reliable information on the health and risk factors of a population of interest. Missing data occur when some invitees do not participate the survey. If non-participation is associated with the variables to be studied, then the estimates based only on the participants cannot be generalised to the population of interest. In this case, the estimates have selection bias, which misleads the decision-makers. The purpose of this thesis is to develop statistical methods to reduce the selection bias in the cross-sectional data using additional data sources. The data, which we use, comes from the National FINRISK Study, and we aim to estimate the prevalences…