A Combined Monte Carlo and Possibilistic Approach to Uncertainty Propagation in Event Tree Analysis

In risk analysis, the treatment of the epistemic uncertainty associated to the probability of occurrence of an event is fundamental. Traditionally, probabilistic distributions have been used to characterize the epistemic uncertainty due to imprecise knowledge of the parameters in risk models. On the other hand, it has been argued that in certain instances such uncertainty may be best accounted for by fuzzy or possibilistic distributions. This seems the case in particular for parameters for which the information available is scarce and of qualitative nature. In practice, it is to be expected that a risk model contains some parameters affected by uncertainties that may be best represented by probability distributions and some other parameters that may be more properly described in terms of fuzzy or possibilistic distributions. In this article, a hybrid method that jointly propagates probabilistic and possibilistic uncertainties is considered and compared with pure probabilistic and pure fuzzy methods for uncertainty propagation. The analyses are carried out on a case study concerning the uncertainties in the probabilities of occurrence of accident sequences in an event tree analysis of a nuclear power plant.     

Robust linear mixed models for Small Area Estimation

Hierarchical models are popular in many applied statistics fields including Small Area Estimation. One well known model employed in this particular field is the Fay–Herriot model, in which unobservable parameters are assumed to be Gaussian. In Hierarchical models assumptions about unobservable quantities are difficult to check. For a special case of the Fay–Herriot model, Sinharay and Stern [2003. Posterior predictive model checking in Hierarchical models. J. Statist. Plann. Inference 111, 209–221] showed that violations of the assumptions about the random effects are difficult to detect using posterior predictive checks. In this present paper we consider two extensions of the Fay–Herriot model in which the random effects are assumed to be distributed according to either an exponential power (EP) distribution or a skewed EP distribution. We aim to explore the robustness of the Fay–Herriot model for the estimation of individual area means as well as the empirical distribution function of their ‘ensemble’. Our findings, which are based on a simulation experiment, are largely consistent with those of Sinharay and Stern as far as the efficient estimation of individual small area parameters is concerned. However, when estimating the empirical distribution function of the ‘ensemble’ of small area parameters, results are more sensitive to the failure of distributional assumptions.     

An Indicator for the Measurement of Political Participation: The Case of Italy

In the modern globalized world, political participation is of paramount importance for balanced socio-economic growth and for human development. The Indagine Multiscopo sulle famiglie, a survey by Italian public institutions (ISTAT and CNEL), provides a wide range of data to evaluate specific aspects of Italian life. This work uses a set of data from the Indagine to analyse political participation in Italy at a regional level, by means of a composite indicator using parametric (Pena’s distance) and non-parametric (Mazziotta–Pareto Index) techniques. We have obtained a ranking that shows the level of political participation in different territorial contexts. The aim is to analyse the relation between Italian regions and the political behaviour of their communities: political discussions, participation in political meetings and marches, voluntary activity or donations to political parties and so on. The ranking is not correlated to voter turnout. We can assume that the politically engaged minority are unable to convince and involve the rest. At the same time, these small groups do not alter the general mistrust in parties and, generally speaking, in politics, which is spreading across Italy and also Europe.     

Diversity patterns of alien and native plant species in Trieste port area: exploring the role of urban habitats in biodiversity conservation

Nowadays, urban areas play a crucial role in biodiversity conservation and habitat protection despite the constant pressures on which these habitats are subjected. They may even host relatively new plant communities due to the peculiar ecosystem where they vegetate. The port of Trieste (NE Italy) is characterized by a mixed mosaic of intensely human impacted areas (where commercial activities are still ongoing) flanked by abandoned areas where vegetation persists or has spontaneously recovered. In this study, we sampled the whole port area through a stratified random sampling by placing multiscalar nested plots in four different habitats (strata) previously identified by photo-interpretation. Plant species richness and abundance were assessed in each plot. Each species was then classified as native or alien and patterns of species richness and complementarity were compared among habitats. Results show that there is a significant difference in species richness patterns among habitats, while observed patterns are likely to vary at different spatial scales. As expected, urban plots account for most of the alien species in the sampling, while wooded plots cope better with invasion, accounting for a lower alien/native ratio. These results highlight how habitat diversity enhances biodiversity in urban areas and how it could provide an effective filtering effect able to reduce the spread of alien species. In addition, we provide further evidence for the use of multi-scale approaches in order to study the complex relationships between spatial heterogeneity and plant species richness.     

Interval-censored data with misclassification: a Bayesian approach

Survival data involving silent events are often subject to interval censoring (the event is known to occur within a time interval) and classification errors if a test with no perfect sensitivity and specificity is applied. Considering the nature of this data plays an important role in estimating the time distribution until the occurrence of the event. In this context, we incorporate validation subsets into the parametric proportional hazard model, and show that this additional data, combined with Bayesian inference, compensate the lack of knowledge about test sensitivity and specificity improving the parameter estimates. The proposed model is evaluated through simulation studies, and Bayesian analysis is conducted within a Gibbs sampling procedure. The posterior estimates obtained under validation subset models present lower bias and standard deviation compared to the scenario with no validation subset or the model that assumes perfect sensitivity and specificity. Finally, we illustrate the usefulness of the new methodology with an analysis of real data about HIV acquisition in female sex workers that have been discussed in the literature.     

The New International Migrations and the Changes in the Labour Market

Abstract. The article intends to point out some of the main changes that are taking place in the structure of the labour market in Europe and the role played by the recent waves of immigration from Third World countries. The main features of these new migratory flows are that they involve a much larger number of states, both as sending and as receiving countries. Secondly the majority of the migrants workers tend to hold secondary labour market jobs or to work in the informal sector. These two aspects make today's international migrations very different from the intraeuropean migratory waves that concerned a much lower number of countries and were directed towards industrial areas.     

Big Data and Social Indicators: Actual Trends and New Perspectives

Big Data are a top subject in international research articles and a vast debate is taking place on their actual capability of being used to complement or even substitute official statistics surveys and social indicators in particular. In this paper we analyse the metadata of the Scopus database of academic articles on Big Data and we show that most of the existing and intensively growing literature is focused on software and computational issues whilst articles that are specifically focused on statistical issues and on the procedures to build social indicators from Big Data are a much smaller share of this vast production. Nevertheless the works that focus on these topics show promising results because in developed countries Big Data seem to be a good information base to create reliable proxies of social indicators, whereas in developing countries their use (for instance using satellite images) may be a viable alternative to traditional surveys. However, Big Data based social indicators deeply suffer of a number of open issues that affect their actual use: they do not correspond to any sampling scheme and they are often representative of particular segments of the population; they generally are private process-produced data whose access by national statistical offices is rarely possible although the intrinsic value of the information contained in Big Data has a social importance that should be shared with the whole community; Big Data lack the socio-economic background on which social indicators have been founded and their help to policy makers in their decision process is a fully open point. Therefore Big Data may be a big opportunity for the definition of traditional or new social indicators but their statistical reliability should be further investigated and their availability and use should be internationally coordinated.     

Unfolding female quiet in wargames: gender bias in Metal Gear Solid V: The Phantom Pain from representation to gameplay

This article investigates the cultural mediatization of the relationship between gender and war by looking at the representation and agency of female presence in one of the most popular sagas in video games: Metal Gear Solid. We have specifically focused on the last chapter of the series, Metal Gear Solid V (MGS5) by putting under scrutiny the character of Quiet. The analysis draws upon the rich theoretical corpus of feminist film studies, with reference to two main concepts: the “visual pleasure” by Laura Mulvey and the “female voice” by Kaja Silverman. These analytic tools are employed in order to scrutinize both the visual representation and the design of the game. We argue that MGS5 is a relevant instance of a large part of gaming production that develops a war imagery characterized by (a) the exploitation of women and (b) an employment of female body as a tool to fulfill the visual pleasure of the male gaze. The figure of Quiet, with the oversexualization of her body and the deprivation of her voice, is particularly telling in this respect. Our analysis aims to identify effective solutions in order to think about more inclusive digital games able to address conflictual issues without surrendering to sexism.     

The Quality of Recent Pacific Sociological Association (PSA) Meetings: Location,Session Quality and Institutional Change

Employing data (n?=?734) collected from those having attended the Pacific Sociological Association (PSA) annual meetings held in San Diego, California (2012) and Reno, Nevada (2013), we test whether session quality and host-city satisfaction are positively associated with how respondents rated the overall quality of the meetings. A majority (54 %) of respondents reported the quality of the meetings highly (“Above Average” or “Excellent”), and suggestive of the importance of conference location, this declined from 64 % in 2012 to 41 % in 2013. Controlling for individual characteristics and institutional affiliation, regression results intimate that both host-city satisfaction and session quality are positively associated with how respondents rated the overall quality of the meetings. And they suggest that the former is somewhat more important than the latter for explaining variation in meeting quality. A final stage of our analysis (n?=?205) finds that attendees’ evaluations of changes in how the 2013 PSA meetings were developed and organized are positively associated with meeting quality without diminishing the independent effects of session or location quality. We discuss implications of these results for future PSA meetings, as well as for research investigating how to improve the quality of regional academic conferences more generally.