196,329 research outputs found
Additive regression modelling for zero inflated Poisson distribution
No full textin S. Zani and A. Cerioli (Eds
Hierarchical latent variable models for dimensionality reduction: an application on composite indicators
No full textThis thesis is devoted to the development of new hierarchical latent variable models for Dimensionality Reduction with a specific focus on the construction of Composite Indicators (CIs). Since our society is producing a huge quantity of data, the construction of model-based CIs represents an interesting and still open methodological challenge. This dissertation is motivated by the necessity to provide model-based CIs which are built according to a statistical approach avoiding subjective choices (e.g., normative weights), therefore, the new insights and proposals hope to represent a contribution to the current literature. This thesis provides an introduction to CIs, a brief review of the most used methods in Multidimensional Data Analysis framework, a discussion about measurement models and methodological proposals to model latent concepts. Factor Analysis and its hierarchical extensions have been introduced in order to set the starting point of the analysis. A first proposal represents a new latent factor model that could be used for building CIs, it aims to investigate the hierarchical structure of the data in order to define two levels of CIs. The model, named Hierarchical Disjoint Non-Negative Factor Analysis is composed of two novelties: a model which is the two level hierarchical extension of FA and its disjoint extension with non-negative loadings. The latter model is enriched by considerations about the CIs used for tracking coherent policy conclusions. A set of features, properties and rules useful to build "good" CIs have been presented and explained. The last proposal in the thesis represents a new model for positive data correlation matrices which aims to detect reliable concepts and to build the hierarchy from them to the most general one. The proposed models are illustrated both via simulation studies and real data applications, to analyze their performances and abilities. In particular, the main application in this thesis regards the construction of a hierarchically aggregated index for the multidimensional phenomenon Waste Management in European Union. Waste Management is becoming even more important for its impact on human-being's lives, and many data have been produced about it, therefore the construction of a CI able to reduce its dimensionality and to highlight the main dimensions of it has a extraordinary usefulness in order to provide support to EU countries' action and policies
Civic participation powered by Ethereum: A proposal
No full textIn the last decade, ICT infrastructures for smart cities have become a reality and the number of projects affecting citizens' lives is growing. In particular, the technology supporting civic participation is mature, although many systems do not reach the needed critical mass, as they are not able to capture the interest of their intended target. To overcome this difficulty, we describe a proposal for encouraging citizens' participation by a reward mechanism based on a civic currency, powered by blockchain tokens, used to recognize civic engagement.
This paper briefly sketches the main features of the system and discusses the development of its proof-of-concept in the context of a university course following an agile process, highlighting the lessons so learned
Statistical models and the Benford hypothesis: a unified framework
No full textThe Benford hypothesis is the statement that a random sample is made of realizations of an absolutely continuous random variable distributed according to Benford’s law. Its potential interest spans over many domains such as detection of financial frauds, verification of electoral processes and investigation of scientific measurements. Our aim is to provide a principled framework for the statistical evaluation of this statement. First, we study the probabilistic structure of many classical univariate models when they are framed in the space of the significand and we measure the closeness of each model to the Benford hypothesis. We then obtain two asymptotically equivalent and powerful tests. We show that the proposed test statistics are invariant under scale transformation of the data, a crucial requirement when compliance to the Benford hypothesis is used to corroborate scientific theories. The empirical advantage of the proposed tests is shown through an extensive simulation study. Applications to astrophysical and hydrological data also motivate the methodology. © 2023, The Author(s)
Enlisting Students in Gamifying Software Testing Education: Results and Key Insights
No full textGamification aims to enhance motivation for a variety of routine tasks by incorporating game elements, such as scoring. In educational settings, students are often the players, and gamification can create a more engaging learning environment that motivates them to achieve academic success. In this paper, we describe an experimental software engineering course where we asked students enrolled in a Master's degree program in Computer Science to play the role of game designers and develop software prototypes for the gamification of software testing education. We outline and compare their three proposals to gamify learning in software testing, which reflect team members' diverse interests and inclinations. As a result, the proposals vary in nature, ranging from a gamified standard web application delivering exercises to a fully-fledged game. User testing provided a preliminary evaluation of their playability. Our lessons learned can guide other academics in designing similar assignments for software engineering students to develop gamification prototypes
Genetic algorithms-based approaches for clustering time series
No full textRevised version of the selected paper presented at the biennal meeting of the Classification and Data Analysis Group (CLADAG) of the Italian Statistical Society which was held in Parma, June 6 - 8 , 2005.
S. Zani, A. Cerioli, M. Riani and M. Vichi Editor
Loop Graphs And Asteroidal Sets
No full text[No abstract available]22179183Alcón, L., de Figueiredo, C.H., Cerioli, M., Gutierrez, M., Meidanis, J., Tree Loop Graphs (2004) Electronic Notes in Discrete Mathematics, 18, pp. 17-23. , Proceedings of LACGA 2004 Full paper accepted for publication in Discrete Applied Mathematics Series on Computational Molecular BiologyAlcón, L., de Figueiredo, C.H., Cerioli, M., Gutierrez, M., Meidanis, J., Loop Graphs with induced cycles (2005) Electronic Notes in Discrete Mathematics, 19, pp. 289-295. , Proceedings of GRACO 2005Setubal, J.C., Meidanis, J., (1997) Introduction to Computational Molecular Biology, , PWS, BostonWalter, J.R., Representations of Chordal Graphs as subtrees of a tree (1978) J. of Graph Theory, 2, pp. 265-26
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