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digital STATISTICA & APPLICAZIONI - 2012 - 1
Digital issue
issue 1 - 2012
publisher Vita e Pensiero
format Digital issue | Pdf
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Decomposition of Zenga’s inequality index by sources
by Paolo Radaelli, Michele M. Zenga, Michele Zenga pages: 29 Download
Estimating the normal population with known coefficient of variation using the optimal ranked set sampling scheme
by Mohd T. Alodat, D.A. Omari pages: 10 Download
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.
Some properties of the new Zenga curve
by K.R. Muraleedharan Nair, N. Sreelakshmi, N. Unnikrishnan Nair pages: 10 Download
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.
Metrics-based Markov chains for Web Analytics
by Sergio Scippacercola pages: 12 Download
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.
Mobility as prevailing direction for transition matrices
by Camilla Ferretti pages: 12 Download
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.
The performance evaluation system of the Ministry of Labour and Social Policies: an analysis of inspection activity
by Enrico Ciavolino, Anna Maria Frasca, Piergiorgio Mossi pages: 13 Download
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.