Il tuo browser non supporta JavaScript!

STATISTICA & APPLICAZIONI - 2004 - 2

digital STATISTICA & APPLICAZIONI - 2004 - 2
Fascicolo digitale
rivista STATISTICA & APPLICAZIONI
fascicolo 2 - 2004
titolo STATISTICA & APPLICAZIONI - 2004 - 2
editore Vita e Pensiero
formato Fascicolo digitale | Pdf
Scrivi un commento per questo prodotto

Ebook in formato Pdf leggibile su questi device:

Secondo fascicolo del 2004

CONTENTS

Kurtosis Diagram for the Log-Dagum Distribution
di_autore Filippo Domma pagine: 21 Scarica
Abstract
The aim of this paper is to study, through the kurtosis diagram proposed by Zenga (1996), the kurtosis of the log-Dagum distribution. In particular, we analyse how changes the kurtosis on the left and right side of the distribution when the parameter β changes, having fixed the median and absolute mean value from the median. We prove that the kurtosis depends only on parameter β and we show that a reduction of the kurtosis on the left side of the diagram and an increse of the kurtosis on the right side of the diagram occours when β increases.

Keywords: Log-Dagum distribution, kurtosis diagram, symmetric and asymmetric distribution.
Random variate generation from Multivariate Exponential Power distribution
di_autore Nadia Solaro pagine: 21 Scarica
Abstract
In this paper two procedures for random variate generation for the family of Multivariate Exponential Power (MEP) distributions are developed and then compared. By conveniently expressing MEP distributions in terms of mixture of random variables, a simple and fast procedure based on transformation approach is proposed. Another procedure, based on a general acceptance-rejection (AR) technique for multivariate orthounimodal densities, is considered. As expected, the transformation-based procedure is considerably less time-consuming than the other one. Furthermore, this study allows us to evaluate to which extent generalizations of AR methods could be computationally less efficient than a transformation one for the type of multivariate distributions considered.

Keywords: acceptance-rejection method, multivariate elliptical and symmetric distributions, multivariate orthounimodal distributions, transformation method.
Ricerca di soglie critiche per un test su matrici di confusione
di_autore Eugenio Brentari, Elena Poli pagine: 13 Scarica
Abstract
This paper will discuss misclassification errors induced by human judgement. Facing different classifications coming from different trials, often researchers have to evaluate the goodness of classification proposed. Particularly, we propose an interesting application concerning olfactory measurement. In that field the accuracy of a confusion matrix is crucial, because the classification suggested by a panel of experts is collected by means of a confusion matrix.
The analysis of a confusion matrix we will perform in this study serves both to evaluate skills of judges, of whom the panel is composed, and to evaluate the discriminant capability of the element used to make the experiment.
This work will focus in establishing critical thresholds for the test thorough which we asses not random classification.

Keywords: Confusion Matrix, Misclassification, Critical Thresholds.
Alcune considerazioni sull’efficienza degli stimatori rapporto-cum-prodotto
di_autore Pier Francesco Perri pagine: 17 Scarica
Abstract
In order to estimate the unknown mean of a study variable using two auxiliary variables, the efficiency of a modified version of the ratio-cum-product estimators is analysed when the sampling fraction is less then 0.5. Approximate expressions for the bias and the mean square error are obtained and specific conditions under which the modified estimators are more efficient then the original ones are analytically defined. Also a comparison with the multivariate regression estimator is included.

Keywords: auxiliary variables, efficiency, sampling fraction, ratio-cum-product estimators, regression estimator.
L’incidenza dei fattori ambientali sul rischio di malattia: un modello anisotropico
di_autore Eugenia Nissi, Annalina Sarra pagine: 15 Scarica
Abstract
In the recent years, there has been growing interest in the development of statistical methods useful in the detection of disease cases related to environmental pollution.
Our starting point is an inhomogeneous Poisson point process model for the spatial variation in the incidence of cases and controls in a designated geographic region, as proposed by Diggle.
In this paper we focus on a particular model with directional effects to analyse the health risk around a point source.
In order to evaluate the adequacy of the proposed model we perform a Monte Carlo simulation study. In particular we analyse the maximum likelihood estimators properties of the model parameters.

Keywords: processi spaziali di punto, regressione binaria, epidemiologia ambientale, modello con effetti direzionali.

News

29.07.2019
Maryanne Wolf al Festivaletteratura
"Come diventiamo lettori" è il titolo del dialogo tra la Wolf e Manguel che si terrà sabato 7 settembre al Festivaletteratura di Mantova.
26.07.2019
Credo: lo recitate senza comprenderlo?
Tomáš Halík, prendendo spunto da un dibattito sul "Credo", si interroga sulla capacità di non rimanere intrappolati nella meccanicità delle formule.
05.07.2019
«Sogno scuole di lettura, prima che di scrittura»
Il commento di Alessandro D'Avenia al libro "Lettore, vieni a casa" in attesa dell'incontro con l'autrice Maryanne Wolf al Festivaletteratura di Mantova.
28.05.2019
Qui, ai margini: anteprima di Esquirol
Anteprima del libro del filosofo catalano Esquirol "La penultima bontà": un illuminante percorso che inizia fuori dal paradiso, ai margini.

Newsletter

* campi obbligatori

Collane

  • Cultura e storia
  • Filosofia morale
  • Grani di senape
  • Le nuove bussole
  • Metafisica e storia della metafisica
  • Punti
  • Relazioni internazionali e scienza politica.ASERI
  • Sestante
  • Studi interdisciplinari sulla famiglia
  • Temi metafisici e problemi del pensiero antico
  • Transizioni
  • Varia. Saggistica
  • Tutte le Collane