Search results for "Statistica"
showing 10 items of 5969 documents
Hybrid kernel estimates of space-time earthquake occurrence rates using the Etas model
2010
The following steps are suggested for smoothing the occurrence patterns in a clustered space–time process, in particular the data from an earthquake catalogue. First, the original data is fitted by a temporal version of the ETAS model, and the occurrence times are transformed by using the cumulative form of the fitted ETAS model. Then the transformed data (transformed times and original locations) is smoothed by a space–time kernel with bandwidth obtained by optimizing a naive likelihood cross-validation. Finally, the estimated intensity for the original data is obtained by back-transforming the estimated intensity for the transformed data. This technique is used to estimate the intensity f…
Dynamic Gaussian Graphical Models for Modelling Genomic Networks
2014
After sequencing the entire DNA for various organisms, the challenge has become understanding the functional interrelatedness of the genome. Only by understanding the pathways for various complex diseases can we begin to make sense of any type of treatment. Unfortunately, decyphering the genomic network structure is an enormous task. Even with a small number of genes the number of possible networks is very large. This problem becomes even more difficult, when we consider dynamical networks. We consider the problem of estimating a sparse dynamic Gaussian graphical model with \(L_1\) penalized maximum likelihood of structured precision matrix. The structure can consist of specific time dynami…
Rejection odds and rejection ratios: A proposal for statistical practice in testing hypotheses
2016
Much of science is (rightly or wrongly) driven by hypothesis testing. Even in situations where the hypothesis testing paradigm is correct, the common practice of basing inferences solely on p-values has been under intense criticism for over 50 years. We propose, as an alternative, the use of the odds of a correct rejection of the null hypothesis to incorrect rejection. Both pre-experimental versions (involving the power and Type I error) and post-experimental versions (depending on the actual data) are considered. Implementations are provided that range from depending only on the p-value to consideration of full Bayesian analysis. A surprise is that all implementations -- even the full Baye…
Bayesian Inference for the Exponential Power Function Parameters
2008
This paper addresses the problem of obtaining the marginal posterior distributions, via Gibbs Sampler, for the parameters of the well-known generalized error distribution called Exponential Power Function (E.P.F.). This density represents a family of unimodal symmetric distributions with shapes varying from leptokurtic to platikurtic.
Operational Quantification of Continuous-Variable Correlations
2007
We quantify correlations (quantum and/or classical) between two continuous variable modes in terms of how many correlated bits can be extracted by measuring the sign of two local quadratures. On Gaussian states, such `bit quadrature correlations' majorize entanglement, reducing to an entanglement monotone for pure states. For non-Gaussian states, such as photonic Bell states, ideal and real de-Gaussified photon-subtracted states, and mixtures of pure Gaussian states, the bit correlations are shown to be a {\em monotonic} function of the negativity. This yields a feasible, operational way to quantitatively measure non-Gaussian entanglement in current experiments by means of direct homodyne d…
Double precision errors in the logistic map: statistical study and dynamical interpretation.
2007
The nature of the round-off errors that occur in the usual double precision computation of the logistic map is studied in detail. Different iterative regimes from the whole panoply of behaviors exhibited in the bifurcation diagram are examined, histograms of errors in trajectories given, and for the case of fully developed chaos an explicit formula is found. It is shown that the statistics of the largest double precision error as a function of the map parameter is characterized by jumps whose location is determined by certain boundary crossings in the bifurcation diagram. Both jumps and locations seem to present geometric convergence characterized by the two first Feigenbaum constants. Even…
Análisis de las publicaciones españolas sobre Documentación e Informática Médica
1994
Se estudia la producción española de documentación e información médicas, en sus distintas áreas de especialización, hasta el año 1991. Se analiza el crecimiento de la producción de los diferentes tipos de documentos sobre la disciplina, así como las materias, instituciones de procedencia y distribución geográfica . Los resultados muestran la gran dispersión de los trabajos sobre el tema y el predominio de los estudios dedicados a la documentación clínica, producidos en instituciones hospitalarias.
IL REGISTRO REGIONALE DELLE CRONICITÀ: NUOVI ALGORITMI PER LA VALUTAZIONE DEI PROFILI DI CONSUMI PER CATEGORIE DIAGNOSTICHE IN SICILIA
2013
Introduzione. Conoscere la prevalenza di una malattia cronica è essenziale per una corretta programmazione delle risorse economiche e umane necessarie per l’implementazione delle strategie preventive e terapeutiche. La Base Dati degli Assistibili (BDA), sviluppata nell’ambito del Piano Operativo di Assistenza Tecnica alle Regioni dell’Obiettivo Convergenza (POAT) cui la Regione Sicilia partecipa attivamente, consente dianalizzare in modo integrato le informazioni provenienti dai diversi flussi informativi che la costituiscono. Obiettivi. Costituire un registro regionale delle cronicità in Sicilia, al fine di valutare i profili di consumi per categorie diagnostiche e stimarne i relativi cari…
Critical behavior of a colloid-polymer mixture confined between walls
2006
We investigate the influence of confinement on phase separation in colloid-polymer mixtures. To describe the particle interactions, the colloid-polymer model of Asakura and Oosawa [J. Chem. Phys. 22, 1255 (1954)] is used. Grand canonical Monte Carlo simulations are then applied to this model confined between two parallel hard walls, separated by a distance D=5 colloid diameters. We focus on the critical regime of the phase separation and look for signs of crossover from three-dimensional (3D) Ising to two-dimensional (2D) Ising universality. To extract the critical behavior, finite size scaling techniques are used, including the recently proposed algorithm of Kim et al. [Phys. Rev. Lett. 91…
Concentration and energy fluctuations in a critical polymer mixture
1995
A semi-grand-canonical Monte Carlo algorithm is employed in conjunction with the bond fluctuation model to investigate the critical properties of an asymmetric binary (AB) polymer mixture. By applying the equal peak-weight criterion to the concentration distribution, the coexistence curve separating the A-rich and B-rich phases is identified as a function of temperature and chemical potential. To locate the critical point of the model, the cumulant intersection method is used. The accuracy of this approach for determining the critical parameters of fluids is assessed. Attention is then focused on the joint distribution function of the critical concentration and energy, which is analysed usi…