Search results for "GiST"
showing 10 items of 3463 documents
Regression models for multivariate ordered responses via the Plackett distribution
2008
AbstractWe investigate the properties of a class of discrete multivariate distributions whose univariate marginals have ordered categories, all the bivariate marginals, like in the Plackett distribution, have log-odds ratios which do not depend on cut points and all higher-order interactions are constrained to 0. We show that this class of distributions may be interpreted as a discretized version of a multivariate continuous distribution having univariate logistic marginals. Convenient features of this class relative to the class of ordered probit models (the discretized version of the multivariate normal) are highlighted. Relevant properties of this distribution like quadratic log-linear e…
Inferential tools in penalized logistic regression for small and sparse data: A comparative study.
2016
This paper focuses on inferential tools in the logistic regression model fitted by the Firth penalized likelihood. In this context, the Likelihood Ratio statistic is often reported to be the preferred choice as compared to the ‘traditional’ Wald statistic. In this work, we consider and discuss a wider range of test statistics, including the robust Wald, the Score, and the recently proposed Gradient statistic. We compare all these asymptotically equivalent statistics in terms of interval estimation and hypothesis testing via simulation experiments and analyses of two real datasets. We find out that the Likelihood Ratio statistic does not appear the best inferential device in the Firth penal…
What subject matter questions motivate the use of machine learning approaches compared to statistical models for probability prediction?
2014
This is a discussion of the following papers: "Probability estimation with machine learning methods for dichotomous and multicategory outcome: Theory" by Jochen Kruppa, Yufeng Liu, Gerard Biau, Michael Kohler, Inke R. Konig, James D. Malley, and Andreas Ziegler; and "Probability estimation with machine learning methods for dichotomous and multicategory outcome: Applications" by Jochen Kruppa, Yufeng Liu, Hans-Christian Diener, Theresa Holste, Christian Weimar, Inke R. Konig, and Andreas Ziegler.
Bayesian Modeling of Sequential Discoveries
2022
We aim at modelling the appearance of distinct tags in a sequence of labelled objects. Common examples of this type of data include words in a corpus or distinct species in a sample. These sequential discoveries are often summarised via accumulation curves, which count the number of distinct entities observed in an increasingly large set of objects. We propose a novel Bayesian method for species sampling modelling by directly specifying the probability of a new discovery, therefore allowing for flexible specifications. The asymptotic behavior and finite sample properties of such an approach are extensively studied. Interestingly, our enlarged class of sequential processes includes highly tr…
Registration and fusion of segmented left atrium CT images with CARTO electrical maps for the ablative treatment of atrial fibrillation
2005
This study aims to extract the interior surface of the left atrium (LA) and pulmonary veins (PVs) from threedimensional tomographic data and to integrate it with LA CARTO electrical maps. The separation of LA and PVs from other overlapping structures of the heart was performed processing 3D CT data by marker-controlled watershed segmentation and surface extraction. CARTO maps were then registered on the L A internal surface by a stochastic optimization algorithm based on simulated annealing. The residual registration error resulted inferior to 3 mm. The integration between electrophysiological and high resolved anatomic information of LA results feasible and may constitute a significant sup…
Nicola Bonacasa e l’insegnamento dell’Archeologia nell’Università di Palermo
2016
Si ripercorre la storia dell'insegnamento di Archeologia nell'Università di Palermo, focalizzando l'attenzione sull'apporto alla sua riorganizzazione da parte di Nicola Bonacasa, a lungo direttore dell'Istituto di Archeologia e presidente dei corsi di studio dell'ambito. It traces the history of the teaching of Archeology at the University of Palermo, focusing attention on the contribution to its reorganization by Nicola Bonacasa, long director of the Institute of Archeology and president of the study courses in the field.
Identificare registrare riconoscere tra medioevo e prima età moderna. Alcune Riflessioni su pratiche siciliane
2015
Specific practices for the identification and the registration of people, not necessarily related to the State control of migration flows, were recorded in Sicily as well as in the rest of Europe in the Middle Ages and in the Early Modern Age. We should consider the need of individuals to establish their condition or to assure themselves certain rights and privileges through some form of registration providing recognition of identity. The matter extends then to other areas such as those of property, testimony, rights and law. Taking advantage of the considerable amount of archival records produced in Sicily in the aforementioned period, the present essay aims to focus on some of the identif…
Productivity change of the Spanish Port System: impact of the economic crisis
2016
The main goal of this study was to assess the impact of the economic crisis on the productivity growth of the Spanish Port System (SPS). The Malmquist Productivity Index (MPI) was estimated for the 28 Port Authorities of the SPS, for a 'non-crisis period' (2005-2008) and a 'crisis period' (2008-2011). From a policy perspective, the MPI is a very useful approach for assessing the productivity change because it can be decomposed into the catching-up index and the frontier productivity index. The results showed that the economic crisis did not impact all of the Spanish Port Authorities equally. Some Port Authorities presented higher productivity growth during the crisis period than in the non-…
Strategic Planning for Integrated Mobility-on-Demand and Urban Public Bus Networks
2020
App-based services and ridesharing in the field of mobility-on-demand (MoD) create a new mode of transport between motorized individual transport and public transportation whose long-term role in the urban mobility landscape and within public transport systems is not fully understood as of today. For the public transport industry, these new services offer new chances but also risks, making planning models and tools for integrated intermodal network planning indispensable. We develop a strategic network planning optimization model for bus lines that allows for intermodal trips with MoD as a first or last leg. Starting from an existing public transport network, we decide simultaneously on th…
Conventions of Quality in Consumer Preference toward Local Honey in Southern Italy
2016
During the last few decades consumer demand for local foods has increased around the world, particularly in the USA and Europe. Such consumer trend also contributes to redefine a new alternative geography of food; in which local foods are perceived to be of better quality and safer. Moreover, consumers frame local food quality not only in terms of general attributes, such as taste and price, but also in terms of more subjective attributes closely linked to social and environmental aspects of products. These attributes are recognised by consumers as a range of socially constructed food quality criteria, which play an important role in the creation of information about quality and consumer de…