Statistical models for e-learning data

In this paper we analyse a real e-learning dataset derived from the e-learning platform of the University of Pavia. The dataset concerns an online learning environment with in-depth teaching materials. The main focus of this paper is to supply a measure of the relative importance of the exercises (test) at the end of each training unit; to build predictive models of student’s performance and finally to personalize the e-learning platform. The methodology employed is based on nonparametric statistical methods for kernel density estimation and generalized linear models and generalized additive models for predictive purposes.     

LR cointegration tests when some cointegrating relations are known

This paper considers the asymptotic analysis of the likelihood ratio (LR), cointegration (CI) rank test in vector autoregressive models (VAR) when some CI vectors are known and fixed. It is shown that the limit law is free of nuisance parameters. In the case of LR tests against the alternative of completely unrestricted CI space, the limit law can be expressed as the convolution of known distributions. This deconvolution is employed to approximate the quantiles of the distribution, without resorting to new simulations.     

Use of quantitative ultrasound as bone mineral density evaluation in an Italian female population living with HIV: A real-life experience

This is a multicenter cross-sectional study where we aimed to detect the rate of osteopenia/osteoporosis in an HIV female population (WLWHIV) by means of “heel quantitative ultrasound” (QUS) measurement. We enrolled 273 patients, mean age 48.1 years, 36% menopausal, 96% on combination antiretroviral therapy (cART). Calcaneal measure of bone mass index by QUS revealed osteopenia and osteoporosis in 76 (27.8%) and 16 (5.9%) WLWHIV. Our data underline the correlation between low QUS parameters and traditional risk factors for osteoporosis rather than with cART exposure, thus suggesting the crucial importance of detection and correction of traditional risk factors for osteoporosis in WLWHIV.     

Monopolistic competition,as you like it

We explore monopolistic competition with asymmetric preferences over a variety of goods provided by heterogeneous firms, and compute equilibria (approximating Cournot and Bertrand equilibria when market shares are negligible) through average Morishima elasticities of substitution. Further results concerning pricing and entry emerge under homotheticity and when demands depend on a common aggregator, as with Generalized Additively Separable preferences. Under additivity we can determine which goods are going to be provided under free entry, as well as the selection effects associated with changes in market size, consumers' income, aggregate productivity, and preference parameters.     

A Scale of Risk

This article proposes a conceptual framework for ranking the relative gravity of diverse risks. This framework identifies the moral considerations that should inform the evaluation and comparison of diverse risks. A common definition of risk includes two dimensions: the probability of occurrence and the associated consequences of a set of hazardous scenarios. This article first expands this definition to include a third dimension: the source of a risk. The source of a risk refers to the agents involved in the creation or maintenance of a risk and captures a central moral concern about risks. Then, a scale of risk is proposed to categorize risks along a multidimensional ranking, based on a comparative evaluation of the consequences, probability, and source of a given risk. A risk is ranked higher on the scale the larger the consequences, the greater the probability, and the more morally culpable the source. The information from the proposed comparative evaluation of risks can inform the selection of priorities for risk mitigation.     

Valori e norme di fronte alla complessità

Riassunto

Scopo del presente contributo è quello di evidenziare alcune connessioni concettuali fra il mondo normativo ed il moderno approccio della complessità.

A partire dal 1972, psicologi, etologi, antropologi culturali hanno sottolineato l'importanza dei codici sociali—oggettivati in diritti e doveri—in quanto parte integrante della interazione sociale. In particolare Calegari e Massimini (1979) hanno sostenuto che Le Costituzioni possono essere analizzate quali organizzazioni gerarchiche di sistemi complessi. Gli autori hanno indicato—nell'ambito di sistemi normativi—delle gerarchie di comprensione e di connessione riferite a centri di controllo di comportamenti registrati nelle Leggi fondamentali. Essi hanno sviluppato un metodo di analisi basato sulla identificazione di unità molari e di loro relazioni ed hanno messo a punto una serie di indici utili a misurare le dimensoni di complessità di tali sistemi.

Sulla base di un sucessivo approfondimento, l'autore ha centrato la sua attenzione sulle decisioni adattive incluse nelle Costituzioni. La conseguente analisi cognitiva mostra che le strategie normative si configurano in livelli (metapiani, piani globali, sottopiani, istruzioni comportamentali) in accordo con la ipotesi sistémica generale formulata da Bruner, Goodnow ed Austin (1966). La organizzazione gerarchica di questo tipo di strategia è caratterizzata dalla valenza e dalla covalenza di piani globali e di sottopiani, dal grado di similarità dei metapiani e dei piani globali, dal grado di ridondanza emergente ai differenti livelli gerarchici.

Le decisioni adattive sono presenti in numero limitato e ciò conferma le stipulazioni formulate dagli antropologi culturali. L'autore sottolinea che la presenza di ridondanza negli elementi di un sistema complesso rende possibile la sua descrizione in modo più coerente e completo.     

The origins of the Gini index: extracts from Variabilità e Mutabilità (1912) by Corrado Gini

The scope of this paper is to celebrate the 100th anniversary of the Gini index by providing the original formulae. Corrado Gini introduced his index for the first time in a 1912 book published in Italian under the name of ??Variabilità e Mutabilità?? (Variability and Mutability). This article provides selected extracts of Part I of the book dedicated to measures of variability. We find that Gini proposed no less than 13 formulations of his index, none of which is known today to the large public. We also find that Gini anticipated some of the developments that derived from the study of his index.     

Guilt in Marketing Research: An Elicitation–Consumption Perspective and Research Agenda

Guilt regulates many consumption processes and, consequently, marketers frequently use appeals based on guilt to influence consumers' behaviour. Owing to the multidisciplinary interest in this emotion, however, the literature is diverse and fragmented. The effectiveness of guilt appeals is contested, and some authors suggest that the use of this emotion in marketing might be unethical. Furthermore, research to date has not explored the potential relationships between the experience of guilt in consumption and the elicitation of this emotion through marketing appeals. This paper analyses existing research on guilt in marketing, developing four specific contributions based on the evidence reviewed. First, it shows under what circumstances feelings of guilt support consumer self‐regulation processes. Second, it outlines evidence‐based managerial recommendations on how to produce effective guilt appeals and avoid the potentially unethical consequences of marketing through this emotion. Third, it identifies a gap in existing theorizing and presents an elicitation–consumption perspective of guilt in marketing as a framework that complements current approaches to this research topic. Fourth, it develops an agenda for future research and suggests eleven research hypotheses for the advancement of this field. Through the analysis of research produced within different disciplinary perspectives, this study develops a necessary foundation for future work on the role of guilt in marketing processes.     

A fuzzy logic approach to poverty analysis based on the Gini and Bonferroni inequality indices

In the poverty analysis framework, a great deal of attention has been paid to the poverty measurement in terms of monetary variables, such as income or consumption. In this context, a relevant open problem is connected with the distinction between poor and non-poor. In fact, the concept of poverty is rather vague and cannot be defined in a clear way. In this respect, following a fuzzy logic approach, some new poverty measures are proposed. In particular, the fuzzy extension of two existing poverty measures based on the Gini and Bonferroni inequality indices is provided. Some synthetic and real applications are given in order to show how the proposed poverty measures work.