Regularization with Maximum Entropy and Quantum Electrodynamics: The Merg(E) Estimators

It is well-known that under fairly conditions linear regression becomes a powerful statistical tool. In practice, however, some of these conditions are usually not satisfied and regression models become ill-posed, implying that the application of traditional estimation methods may lead to non-unique or highly unstable solutions. Addressing this issue, in this paper a new class of maximum entropy estimators suitable for dealing with ill-posed models, namely for the estimation of regression models with small samples sizes affected by collinearity and outliers, is introduced. The performance of the new estimators is illustrated through several simulation studies.     

Layered adaptive importance sampling

Monte Carlo methods represent the de facto standard for approximating complicated integrals involving multidimensional target distributions. In order to generate random realizations from the target distribution, Monte Carlo techniques use simpler proposal probability densities to draw candidate samples. The performance of any such method is strictly related to the specification of the proposal distribution, such that unfortunate choices easily wreak havoc on the resulting estimators. In this work, we introduce a layered (i.e., hierarchical) procedure to generate samples employed within a Monte Carlo scheme. This approach ensures that an appropriate equivalent proposal density is always obtained automatically (thus eliminating the risk of a catastrophic performance), although at the expense of a moderate increase in the complexity. Furthermore, we provide a general unified importance sampling (IS) framework, where multiple proposal densities are employed and several IS schemes are introduced by applying the so-called deterministic mixture approach. Finally, given these schemes, we also propose a novel class of adaptive importance samplers using a population of proposals, where the adaptation is driven by independent parallel or interacting Markov chain Monte Carlo (MCMC) chains. The resulting algorithms efficiently combine the benefits of both IS and MCMC methods.     

Driving complementarity in interdisciplinary research: a reflection

ABSTRACT

The value of interdisciplinary research is increasingly recognised by the research community. Funding bodies are nowadays specifically encouraging that research they fund is interdisciplinary in nature. However, what is often branded as interdisciplinary research is in fact a network of researchers working to deliver a research output. In this research note, we share our experience of what we think can be labelled “truly interdisciplinary”. We share some best practice tips for those who are interested to go through a similar metamorphosis as we did as a team, learning from each other’s ways of working. Overall, it has been a very positive experience and a revelation that has had a big impact on each author’s view on how to conduct research as an integrated multidisciplinary team, as it has shifted our mental models and broadened our thinking, capacity to reflect, and critical analysis. We hope that our research note clearly shows the benefits of truly interdisciplinary research and motivates other researchers to follow our pathway of transformation.     

Adult self-sufficiency and social adjustment in care leavers from children's homes: a long-term assessment

This paper presents a study carried out in Spain that followed up 260 young people, the majority of them adults, who had been in residential care for significant periods. The follow‐up takes place between 1 and 9 years after participants had left residential care, and assesses their level of social and work integration, as well as considering the incidence of problems related to marginalization and social exclusion. Furthermore, it analyses the reasons for the child being taken into care, the socio‐family context, length of stay, changes in placement and other features or incidents in relation to the residential care. The data show that close to 15% have serious problems (drug dependence, delinquency, etc.), 25% receive help from the social services and the rest manage independently to a greater or lesser extent. We discuss the significance of these data, especially the relationship between the final result and the initial and process variables.     

Support provided by elderly in Italy: a hierarchical analysis of ego networks controlling for alter–overlapping

Statistical Methods & Applications - Providing support outside the household can be considered an actual sign of an active social life for the elderly. Adopting an ego–network...     

Friends don't let friends ...or do they? Developmental and gender differences in intervening in friends' ATOD use

This study focused on the strategies adolescents endorsed for situations in which friends were experimenting with alcohol, tobacco, and other drugs. Four hypothetical vignettes (concerning a friend smoking, using drugs, getting drunk at a party, or deciding whether to attend a party with alcohol and drugs) were presented to 2697 5th-12th graders. Whereas younger students were more likely to choose proactive strategies (talking to the friend or an adult or ending the friendship), older students were more inclined to say they would ignore a friend's smoking and drug use although they would take the car keys away from a friend drinking alcohol. Among those 13 years old and older, the more dangerous the substance, the more inclined the youth were to intervene. Females were more inclined than males to talk to friends about smoking, drinking, and drugs and less inclined to ignore the behaviors or stop being a friend.     

Explaining offline and online civic engagement intentions between Italian and migrant youth / Análisis de las intenciones de participación cívica virtual y presencial entre jóvenes italianos y emigrantes

The aim of the study was to assess the role of some psychosocial factors in explaining offline and online civic engagement intentions in a sample of Italian and second generation migrant (Albanian and Moroccan) adolescents and young adults living in Italy. The theoretical model was an extended version of the Theory of Planned Behaviour including past experience. The sample included 598 adolescents and young adults (M = 19.32, SD = 3.17). Two hundred were Italian (88 males, 44.0%), 197 migrants of Albanian origin (130 males, 66%) and 201 migrants of Moroccan origin (116 males, 57.7%). Moroccan youth reported higher levels of both past civic engagement and future intentions than Albanian and Italian peers. Perceived effectiveness of civic engagement and past experience are consistently associated with stronger intentions to engage in the future (offline and online) in all groups. Internal efficacy plays a limited role, whereas the role of subjective norms differs according to the group and the source of normative influence (parents, peers).     

Social Participation, Sense of Community and Social Well Being: A Study on American, Italian and Iranian University Students

Aim of the study was to assess the relationship between social participation and Sense of Community in a sample of University students and the impact of such variables on Social well being. A further aim was to assess the generality of the relationships between these constructs across different countries, and specifically, the USA, Italy and Iran. The sample includes 200 Italian, 125 American and 214 Iranian University students, male and female. Results show higher levels of social participation, Sense of Community and Social well being among American students. Sense of Community is positively correlated with social participation in all three samples; however, only among Italian students social participation positively predicts Social well being. Implications of results will be discussed.     

Analyse diachronique d'un conseil traditionnel (Colombie)*

This paper is concerned with the role of the traditional council of authorities (cabildo) in a Columbian community of Indian origin. It is shown that its evolution reflects that of the community, since the cabildo has always been essentially an interaction mechanism between the community and the external society, more than the head of an autonomous body. Moreover, this mechanism has mostly been a tool, in the hands of the colonial and, later, national upper class, for manipulating the Indians. The institution was first imposed upon the Indians to ensure their political submission to and economic integration into colonial capitalistic society. In Columbia, this leads to a relatively rapid acculturation of the Indians. During the Republic, a major change occurred when the national economy ceased to rest upon a tributary exploitation of the Indians: landlord/tenant relationships made local community structures useless. Many managed to survive, though, when they were able to keep a certain amount of land on which their members could lead an independent life. The community under study was among these, although its lands were drastically reduced (the better parts being grabbed by adjacent landowners). The local authorities, left without any power to stop these abuses, saw their roles confined to the solution of internal petty disputes. From 1920 on, the further integration of the community in the national economy, through intensive cash-cropping, has gradually made even this reduced role redundant. The author believes that in the study of peasant political systems, a diachronic study of the interrelationships between the economic and the political level is necessary if the understanding is to be complete.