Clustering-based measurement of dependence

A measure of the dependence of a multivariate response variable upon a categorical variable is introduced. Its characteristics are explored via simulations by referring to a specific mixture association model. Inferential aspects are investigated using a permutation test approach. We present preliminary results

Towards a consolidation of worldwide journal rankings - A classification using random forests and aggregate rating via data envelopment analysis

AbstractThe question of how to assess research outputs published in journals is now a global concern for academics. Numerous journal ratings and rankings exist, some featuring perceptual and peer-review-based journal ranks, some focusing on objective information related to citations, some using a combination of the two. This research consolidates existing journal rankings into an up-to-date and comprehensive list. Existing approaches to determining journal rankings are significantly advanced with the application of a new classification approach, ‘random forests’, and data envelopment analysis. As a result, a fresh look at a publication׳s place in the global research community is offered. While our approach is applicable to all management and business journals, we specifically exemplify the relative position of ‘operations research, management science, production and operations management’ journals within the broader management field, as well as within their own subject domain

L’analisi delle relazioni tra corsi di vita: un approccio basato sull’analisi delle sequenze

si introducono metodi per valutare l'associazione tra corsi di vita rappresentati per mezzo di sequenz

Graphical and smoothing techniques for sequence analysis

We consider the problem of the visualisation of life courses represented as sequences. We describe the state of the art and introduce new plots which improve the graphical display of sequences unveiling their most salient features. Our proposal is based upon the application of smoothing techniques, reducing if not completely removing individual noises. The advantages of our plots are illustrated using data from the Panel study of Social Integration in the Netherlands (PSIN)

Grouping and Classifying using CART

Si illustra come ottenere alberi di classificazione quando l’oggetto di interesse è troppo complesso per essere “trattato” con le consuete tecniche. Si suppone di disporre di una matrice di dissimilarità che sintetizza le differenze tra i diversi individui con riferimento all’oggetto di interesse. Si illustra come ottenere gruppi di casi omogenei e simultaneamente prevedere l’appartenenza al gruppo, estendendo la tecnica CART al caso in esame, considerando i problemi di generazione dell’albero, sua potatura e cross-validazion

Transition to parenthood and HIV infection in rural Zimbabwe

Background The relationship between the risk of acquiring human immunodeficiency virus (HIV) infection and people’s choices about life course events describing the transition to parenthood–sexual debut, union (in the form of marriage, cohabitation, or long-term relationship), and parenthood–is still unclear. A crucial role in shaping this relationship may be played by the sequence of these events and by their timing. This suggests the opportunity to focus on the life courses in their entirety rather than on the specific events, thus adopting a holistic approach that regards each individual’s life course trajectory as a whole. Methods We summarise the individual life courses describing the transition to parenthood using ordered sequences of the three considered events. We aim to (i) investigate the association between the sequences and HIV infection, and (ii) understand how these sequences interact with known mechanisms for HIV transmission, such as the length of sexual exposure and the experience of non-regular sexual partnerships. For this purpose, we use data from a general population cohort study run in Manicaland (Zimbabwe), a Sub-Saharan African area characterised by high HIV prevalence. Results For both genders, individuals who experienced either premarital or delayed childbearing have higher HIV risk compared to individuals following more standard transitions. This can be explained by the interplay of the sequences with known HIV proximate determinants, e.g., a longer exposure to sexual activity and higher rates of premarital sex. Moreover, we found that people in the younger birth cohorts experience more normative and safer sequences. Conclusions The shift of younger generations towards more normative transitions to parenthood is a sign of behaviour change that might have contributed to the observed reduction in HIV prevalence in the area. On the other hand, for people with less normative transitions, targeted strategies are essential for HIV prevention