Il tuo browser non supporta JavaScript!

Libri in offerta

First applications of a new three-parameter distribution for non-negative variables
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 2
Anno: 2012
SUMMARY Zenga (2010a) recently proposed a new three-parameter family of density functions for non-negative variables. Its properties resemble those of economic size distributions: it has positive asymmetry, Paretian right tail and it may be zeromodal, unimodal or even bimodal. In this paper we explore some methods for fitting the new density to empirical income distributions. We will see that D’Addario’s invariants method clearly outperforms Pearson’s moments method, which does not seem to work well with heavy tailed distributions. Further, we propose some new methods based on the minimization of a measure for the goodness of fit, imposing restrictions on the parameter space to preserve some features of the empirical distribution in the fitted model. We will see that these methods provide very satisfactory results with income distributions from Italy, Swiss, US and UK. Keywords: Income Distribution, Zenga’s Distribution, Goodness of Fit, Moments Method, Invariants Method.
Scarica
Estimation of the variance for logistic distribution under ranked set sampling and simple random sampling: a comparative study
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 2
Anno: 2012
SUMMARY The logistic distribution is applicable in many area of research. In this study, several estimators of the variance when the location parameter is known and unknown are considered when data are gathered under simple random sampling (SRS) and ranked set sampling (RSS). For some estimators considered, the bias and mean square error (MSE) are not gotten in closed form. Using Monte Carlo simulations, comparison of these estimators is made based on biases, MSE and efficiency. When the estimators are compared, it is found that estimators based on maximum likelihood method are more efficient than other estimators considered, under both SRS and RSS. However, estimators based on RSS have more advantages over those based on SRS. Keywords: Logistic Distribution, Ranked set Sampling, Simple Random Sampling, Variance, Estimations.
Scarica
Regression model for proportions with probability masses at zero and one
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 2
Anno: 2012
SUMMARY In many settings, the variable of interest is a proportion with high concentration of data at the boundaries. This paper proposes a regression model for a fractional variable with nontrivial probability masses at the extremes. In particular, the dependent variable is assumed to be a mixed random variable, obtained as the mixture of a Bernoulli and a beta random variables. The endpoints of zero and one are modelled by a logistic regression model. The values belonging to the interval (0,1) are assumed to be beta distributed and their mean and dispersion are jointly modelled by using two link functions. The regression model proposed here accommodates skewness and heteroscedastic errors. Finally, an application to loan recovery process of Italian banks is also provided. Keywords: Proportions, Mixed Random Variable, Beta Regression, Skewness, Heteroscedasticity.
Scarica
The analysis of the passenger satisfaction as a formative second-order construct
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 2
Anno: 2012
SUMMARY The aim of the paper is to define a new concept of global measure for the Passenger Satisfaction (PS), conceived as second-order latent variables (Henseler and Chin, 2010), and a new estimation approach to its measurement. This idea arises from theoretical and methodological limits of the existent models in correctly capturing the construct of satisfaction and the relationships with its subdimensions. The two main approaches to the estimation of higher-order constructs through the Partial Least Squares Path Modeling (PLS-PM) are presented: the so called Repeated Indicators and the Two-Step approaches. Some criticisms of these methodologies are highlighted and a solution to the issue of the identification of formative second-order constructs is suggested through the adoption of a Hybrid Two-Step approach for solving the presented PS case study. Three ways of modeling PS are then compared: a Base Model, where PS is measured as a traditional first-order construct, and two second-order models estimated, respectively, through the Repeated Indicators and the Hybrid Two-Step. Results are discussed. Keywords: Passenger Satisfaction, Second Order Latent Variables, Partial Least Squares Path Modeling, Hybrid Two-Step Approach.
Scarica
Summaries
Gratis
digital
formato: Articolo | STUDI DI SOCIOLOGIA - 2012 - 2
Anno: 2012
Scarica
EDITORIALE: Servi della Parola
Gratis
digital
formato: Articolo | LA RIVISTA DEL CLERO ITALIANO - 2012 - 2
Anno: 2012
Scarica
Decomposition of Zenga’s inequality index by sources
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
Scarica
Estimating the normal population with known coefficient of variation using the optimal ranked set sampling scheme
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
SUMMARY In the ranked set sampling with set size equal to m, there are mm different possible sampling schemes. The aim of this paper is to characterize the optimal sampling scheme via the Fisher information numbers for normal distribution with known coefficient of variation. Moreover, we use the optimal sampling schemes to obtain unbiased estimators for the mean. Also we compare the estimators to their counterparts under the McIntyre’s ranked set sampling scheme. We show that the MLE under optimal sampling scheme is asymptotically more efficient than its counterpart under McIntyre’s RSS. Keywords: Ranked Set Sampling, Fisher Information, Maximum Likelihood, Normal Distribution, Coefficient of Variation.
Scarica
Some properties of the new Zenga curve
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
SUMMARY In the present communication, we discuss some properties of the new Zenga measure I (p) for inequality. Unlike the Lorenz curve, the I (p) curve can be decreasing, increasing and non-monotonic. Various conditions for monotonicity of I (p) are presented. Further some results on a stochastic order based on I (p) are also established. Keywords: Zenga Curve, Lorenz Curve, Stochastic Order, Quantiles.
Scarica
Metrics-based Markov chains for Web Analytics
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
SUMMARY Today the Web Pages with static contents (e.g. on line newspapers, public portals, didactic pages, etc.) are very widespread by Information Technology. These pages are carriers of knowledge so it is important to study their use. The common web analytics tools lack useful metrics for an evaluation of the dissemination of knowledge via the web. In this paper we propose a Method (called Knowledge Page Markovian Algorithm) that uses the Markov Chains on the data obtained from web analytics tools to evaluate the use of the knowledge pages. By this original approach, it is possible to create new Metrics to assess each web page for the eventual reengineering of the site. Finally, an application of the Method is shown on a website for three University Courses. Keywords: Web Analytics, Metrics, Knowledge Page, Markov Chains.
Scarica
Mobility as prevailing direction for transition matrices
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
SUMMARY Mobility indices are important tools for summarizing and comparing the dynamics of different samples. A mobility index is defined as a function which assigns a real value I to a given transition matrix . The function I ðPÞ, where P is the transition matrix, is chosen to describe a specific type of mobility (e.g. the tendency to leave the current state). In this paper we develop a family of mobility indices capable of embodying information on both the intensity and the prevailing direction of mobility in the sample under study. Keywords: Mobility Index, Transition Matrix, Prevailing Direction.
Scarica
The performance evaluation system of the Ministry of Labour and Social Policies: an analysis of inspection activity
Gratis
digital
formato: Articolo | STATISTICA & APPLICAZIONI - 2012 - 1
Anno: 2012
SUMMARY For several years it has become the practice of Public Administration quality assessment as part of the institutional activities carried out by offices to improve public services by monitoring the production process. The Ministry of Labour and Social Policies has adopted a system of ‘‘quality assessment’’ based on indicators selected as representative of the inspection carried out in decentralized offices. This scoring system – called Project Quality – is defined by three ‘‘synthetic indicators’’ determined periodically by the 92 Provincial Labour Directorates (in Italian: Direzioni Provinciali del Lavoro – DPL) operating in the country. It does indeed have a rating system that defines a ranking among the offices. This paper presents the results of the research in order to analytically describe the performance level with a different model and also suggesting the possible influence exerted by ‘‘local context variables’’, i.e., those relating to the geo-socio-economic differentials, in explaining the efficiency of inspection. The data are analyzed according to the variable inspection and local was formalized through a second-order structural equations model. Keywords: PLS Path-Modeling, Second Order Latent Variables, Performance Evaluation, Context Variables; Inspection Activity.
Scarica

News

24.05.2019
Festival Economia: Scusi prof cos'è il populismo?
Sabato 1°giugno alle 15.00 Andrea Boitani e Rony Hamaui saranno ospiti al Festival dell'Economia di Trento per presentare il loro nuovo libro.
16.05.2019
Funzionare o esistere? Benasayag a Milano
Il 7 giugno ai Frigoriferi Milanesi dialogo tra il filosofo argentino Miguel Benasayag e lo psicanalista Luigi Zoja.
04.03.2019
Diritto penale a processo: il bene non è impaziente
La giustizia fai da te, l'inasprimento delle punizioni, il dito social che giudica le sentenze: intervista a Gabrio Forti sullo stato di salute del diritto penale.
04.02.2019
Rembrandt e le sue ombre
"Rembrandt a Emmaus" è il libro di Max Milner dedicato alla sfida dei pittori, su tutti Rembrandt, di rappresentare il brano di Luca sull'incontro con Gesù.

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