Adolescent Psychological Well‐being,Radicalism, and Activism: The Mediating Role of Social Disconnectedness and the Illegitimacy of the Authorities

The identification of factors that counter youth’s radicalization while promoting democratic activism is a timely social issue. This paper examines the association of psychological well‐being (PWB) with violent radicalism and nonviolent activism, by focusing on the mediating role of both social disconnectedness (SD) and the perceived illegitimacy of the authorities (PIoA). Two mediation structural equation models (full vs. partial) were applied to data collected from 328 Italian adolescents (14–19 years). The results showed how SD and PIoA fully mediated the link of PWB with radicalism (negatively) and activism (positively). This model was further supported when compared with an alternative one proposing PWB as a mediator between SD and PIoA. The findings are discussed in light of the existing literature and provide potential implications for practice.     

Parameter estimation in the classical occupancy model

Under the classical occupancy model, balls are randomly and independently allocated into cells (by assuming that each arrangement of balls is equally probable) in such a way that the random variable of interest is the empty cell number. In some practical applications the total cell number is known and the target parameter turns out to be the number of balls which is estimated on the basis of the observed empty cell count. For instance, the classical occupancy model is commonly adopted for airborne-microorganism abundance estimation, a topic of central importance in environmental microbiology, in aerobiology and in occupational medicine. The classical occupancy model is also applied to the analysis of US National AIDS surveillance data (which are inflated by duplicate reporting) in order to estimate the true population size of AIDS cases. Since many inaccuracies and misunderstandings are present in applied literature, the aim of the present paper is to introduce a formal analysis of the inferential issues connected with the estimation of the number of balls.     

Exploring the absolutist vs relativist perception of poverty using a cross-country questionnaire survey

Questionnaires eliciting the absolutist vs relativist perception of poverty are administered to 1941 undergraduate students in eight countries - Bolivia, Brazil, Italy, Kenya, Laos, Sweden, Switzerland and the UK. We find that the perception of poverty expressed by a large fraction of respondents exhibits both absolutist and relativist concerns, with the former components prevailing over the latter. High-income countries exhibit a significantly more pronounced relativist attitude. Personal characteristics such as past experience of material hardship and relative standard of living play a germane role in shaping respondents’ views.     

Some measures of kurtosis and their inference on large datasets

AStA Advances in Statistical Analysis - This paper deals with the estimation of kurtosis on large datasets. It aims at overcoming two frequent limitations in applications: first, Pearson's...     

Bayesian analysis of dynamic magnetic resonance breast images

Summary.  We describe an integrated methodology for analysing dynamic magnetic resonance images of the breast. The problems that motivate this methodology arise from a collaborative study with a tumour institute. The methods are developed within the Bayesian framework and comprise image restoration and classification steps. Two different approaches are proposed for the restoration. Bayesian inference is performed by means of Markov chain Monte Carlo algorithms. We make use of a Metropolis algorithm with a specially chosen proposal distribution that performs better than more commonly used proposals. The classification step is based on a few attribute images yielded by the restoration step that describe the essential features of the contrast agent variation over time. Procedures for hyperparameter estimation are provided, so making our method automatic. The results show the potential of the methodology to extract useful information from acquired dynamic magnetic resonance imaging data about tumour morphology and internal pathophysiological features.     

Refusal to Answer Specific Questions in a Survey: A Case Study

It is well known that non ignorable item non response may occur when the cause of the non response is the value of the latent variable of interest. In these cases, a refusal by a respondent to answer specific questions in a survey should be treated sometimes as a non ignorable item non response. The Rasch-Rasch model (RRM) is a new two-dimensional item response theory model for addressing non ignorable non response. This article demonstrates the use of the RRM on data from an Italian survey focused on assessment of healthcare workers’ knowledge about sudden infant death syndrome (that is, a context in which non response is presumed to be more likely among individuals with a low level of competence). We compare the performance of the RRM with other models within the Rasch model family that assume the unidimensionality of the latent trait. We conclude that this assumption should be considered unreliable for the data at hand, whereas the RRM provides a better fit of the data.     

Varying levels of anomie in Europe: a multilevel analysis based on multidimensional IRT models

Recent years have seen increased attention paid to monitoring social anomie and its dependency on micro- and macro-factors. In this paper, we endorse the theorisation of social anomie as a complex, multidimensional and multilevel phenomenon. To ensure a rigorous measurement of the varying levels of social anomie in the European countries, the current study relies on a multilevel multidimensional item response theory model which explicitly accounts for the presence of a non-ignorable missing data mechanism. This unified approach makes it possible to specify an analytical model of links between anomie features and their determinants and to explore how the latent traits of interest are influenced by individual-level factors, as well as by country-level indicators. Additionally, to avoid misleading inferential conclusions, the proposed model takes into account the respondent’s omitting behaviour, assuming that the missingness mechanism is driven by a latent propensity to respond. Data used in this study have been collected in the 2010 wave of the European Social Survey. To reduce the computational complexities, a Bayesian specification of the MIRT model is provided and the parameter model estimates are obtained through MCMC algorithms.     

A note on a universal random variate generator for integer-valued random variables

A universal generator for integer-valued square-integrable random variables is introduced. The generator relies on a rejection technique based on a generalization of the inversion formula for integer-valued random variables. This approach allows to create a dominating probability function, whose evaluation solely involves two integrals depending on the characteristic function of the random variable to be generated. The proposal gives rise to a simple algorithm which may be implemented in a few code lines and which may show good performance when the classical families of distributions—such as the Poisson and the Binomial—are considered. In addition, applications to the Poisson-Tweedie and the Luria-Delbrück distributions are provided.     

Assessors

The application of technology, such as interactive digital whiteboards, in the online environment of higher education, is growing at an accelerated pace. Much is known about the tools used in an on-ground course to promote student engagement, but the literature is scant on tools to promote student engagement in the online environment. The purpose of this study is to explore qualitative data from students on faculty efforts to promote student engagement through leveraged digital whiteboard technology. A qualitative review of feedback from graduate students (n = 81) qualitative responses from open-ended questions and follow up online focus group sessions (n = 9) indicate that this technology can be useful to promote a sense of social engagement among students. It is expected that this knowledge will help instructors to better understand what promotes student engagement in an online graduate social work cohort. This learning tool can be used to promote further engagement in future assignments.