Weak disintegrability as a form of preservation of coherence

Summary Weak disintegrations are investigated from various points of view. Kolmogorov's definition of conditional probability is critically analysed, and it is noted how the notion of disintegrability plays some role in connecting Kolmogorov's definition with the one given in line with de Finetti's coherence principle. Conditions are given, on the domain of a prevision, implying the equivalence between weak disintegrability and conglomerability. Moreover, weak sintegrations are characterized in terms of coherence, in de Finetti's sense, of, a suitable function. This fact enables us to give, an interpretation of weak disintegrability as a form of “preservation of coherence”. The previous results are also applied to a hypothetical inferential problem. In particular, an inference is shown to be coherent, in the sense of Heath and Sudderth, if and only if a suitable function is coherent, in de Finetti's sense. Research partially supported by: M.U.R.S.T. 40% “Problemi di inferenza pura”.     

Sensitivity Analysis Using Risk Measures

In a quantitative model with uncertain inputs, the uncertainty of the output can be summarized by a risk measure. We propose a sensitivity analysis method based on derivatives of the output risk measure, in the direction of model inputs. This produces a global sensitivity measure, explicitly linking sensitivity and uncertainty analyses. We focus on the case of distortion risk measures, defined as weighted averages of output percentiles, and prove a representation of the sensitivity measure that can be evaluated on a Monte Carlo sample, as a weighted average of gradients over the input space. When the analytical model is unknown or hard to work with, nonparametric techniques are used for gradient estimation. This process is demonstrated through the example of a nonlinear insurance loss model. Furthermore, the proposed framework is extended in order to measure sensitivity to constant model parameters, uncertain statistical parameters, and random factors driving dependence between model inputs.     

Cautious Expected Utility and the Certainty Effect

Many violations of the independence axiom of expected utility can be traced to subjects' attraction to risk‐free prospects. The key axiom in this paper, negative certainty independence ([Dillenberger, 2010]), formalizes this tendency. Our main result is a utility representation of all preferences over monetary lotteries that satisfy negative certainty independence together with basic rationality postulates. Such preferences can be represented as if the agent were unsure of how to evaluate a given lottery p; instead, she has in mind a set of possible utility functions over outcomes and displays a cautious behavior: she computes the certainty equivalent of p with respect to each possible function in the set and picks the smallest one. The set of utilities is unique in a well defined sense. We show that our representation can also be derived from a “cautious” completion of an incomplete preference relation.     

Clustering in weighted networks

In recent years, researchers have investigated a growing number of weighted networks where ties are differentiated according to their strength or capacity. Yet, most network measures do not take weights into consideration, and thus do not fully capture the richness of the information contained in the data. In this paper, we focus on a measure originally defined for unweighted networks: the global clustering coefficient. We propose a generalization of this coefficient that retains the information encoded in the weights of ties. We then undertake a comparative assessment by applying the standard and generalized coefficients to a number of network datasets.     

Decomposition of the main effects and interaction term by using orthogonal polynomials in multiple non symmetrical correspondence analysis

The multiple non symmetric correspondence analysis (MNSCA) is a useful technique for analyzing a two-way contingency table. In more complex cases, the predictor variables are more than one. In this paper, the MNSCA, along with the decomposition of the Gray–Williams Tau index, in main effects and interaction term, is used to analyze a contingency table with two predictor categorical variables and an ordinal response variable. The Multiple-Tau index is a measure of association that contains both main effects and interaction term. The main effects represent the change in the response variables due to the change in the level/categories of the predictor variables, considering the effects of their addition, while the interaction effect represents the combined effect of predictor categorical variables on the ordinal response variable. Moreover, for ordinal scale variables, we propose a further decomposition in order to check the existence of power components by using Emerson's orthogonal polynomials.     

Theorizing the social: Émile Durkheim's theory of force and energy

This paper offers a new interpretation of Émile Durkheim's The Elementary Forms of Religious Life (1912) as the basis for reconsidering the Tarde–Durkheim debate of 1903 and the distinctions between a theory of social force and a theory of social assemblage. Resisting traditional interpretations of Durkheim's scientism, this essay traces how concepts of force and energy are centrally developed in Elementary Forms to draw new lines between epistemology to ontology for twentieth-century theory. I argue that Durkheim develops an ‘energetic epistemology’ that conceives of the human capacity for shared meaning as a product of invested energy in the form of continually enacted and evolving material practice, thought, and attention. According to Durkheim, when a member of a collective perceives a god or feels belief, he or she actually perceives the accumulated energy of on-going creation and maintenance of objects and ideas by members of a collective. Sacred objects, images, and ideas bear the trace of collective energy the more they are carefully crafted, maintained in spaces that are specially arranged, and written into behavioural codes. This reading of Durkheim allows us to consider him in a lineage of social constructivists and, particularly, in relation to Ludwik Fleck, who has been largely confined to different theoretical discussions when his contributions to sociology have been acknowledged at all. By reconsidering Durkheim, we have occasion to rethink his sociology and understand how he redrew the lines between thought and action, between epistemology and ontology, through the material framework of energy and force.     

Does the compensation level of outside director depend on its personal profile? Some evidence from UK

Combining human capital theory and equity theory, we developed and tested a model in which the outside directors’ total cash compensation is related to the outsider’s profile, as well as to the board and firm characteristics. Consistent with our model, characteristics of the outsider’s profile, in terms of his/her role and responsibility, meeting activities and length of service, are relevant. Only the director’s popularity, as a part of his/her human capital, has a significant effect on his/her compensation. Our empirical results confirm the necessity to create a stronger link between the remuneration policies of the outsider directors and their contribution in a board, in terms of human capital. The remuneration policies adopted by firms should be linked to practices on corporate governance useful for helping outsiders contribute confidently to their work of the board and receive ongoing support and information so they can develop their understanding of the total environment within they work. Then, we suggest having recourse to qualifications and professional skills as well as to specific training or board induction programmes defined by firms themselves. Finally, the Combined Code should promote the adoption and spreading of such practices on market.     

Huntington's disease

In this case study, we describe the symptoms, neurological exam, neuropsychological test results, and brain pathology of a man who died with Huntington's disease (HD). HD is a rare neurodegenerative disease. Like other movement disorders involving the basal ganglia, HD affects motor, cognitive, and psychiatric functioning. The disease follows an autosomal dominant pattern of inheritance, with onset of symptoms most commonly occurring in the late 30s or early 40s, as in this patient. HD is caused by an unstable expansion of the trinucleotide CAG, coding for glutamine, on chromosome 4. Despite knowledge of the gene mutation responsible for HD, no definitive treatment is currently available to slow or halt progression of the disease. However, symptomatic treatment can significantly improve the quality of life for patients with HD.     

Behavioural Addictions in Adolescents and Young Adults: Results from a Prevalence Study

Our study aims to assess the prevalence of behavioural addictions in an adolescent population, evaluating the effects of gender and age, and to assess the correlations among different behavioural addictions. 2853 high school students were assessed in order to evaluate the prevalence of behavioural addictions such as Pathological Gambling (PG), Compulsive Buying (CB), Exercise Addiction (EA), Internet Addiction (IA), and Work Addiction (WA), in a population of Italian adolescents. The South Oaks Gambling Screen-Revised Adolescent (SOGS-RA), the Compulsive Buying Scale (CBS), the Exercise Addiction Inventory (EAI), the Internet Addiction Test (IAT), and the Work Addiction Risk Test (WART), were compiled anonymously by the students. Overall prevalence was 7.0% for PG, 11.3% for CB, 1.2% for IA, 7.6% for WA, 8.5% for EA. PG and EA were more common among boys, while gender had no effect on the other conditions. CB was more common among younger (<18 years old) students. The scores of all of these scales were significantly correlated. The strong correlation among different addictive behaviours is in line with the hypothesis of a common psychopathological dimension underlying these phenomena. Further studies are needed to assess personality traits and other clinical disorders associated with these problems behaviours.