Neurocognitive Effects in Welders Exposed to Aluminium: An Application of the NPC Test and NPC Ranking Methods

The aim of this study is to investigate the effects of exposure to aluminium on the cognitive sphere in a group of welders. Given the intrinsic complexity of the neurocognitive sphere, three different psychomotor variables were used for its investigation allowing the resulting problem to be naturally modelized into a multivariate framework and solved by a nonparametric combination of permutation tests (NPC test). In order to make the treated and control groups comparable, we also stratified the samples on the basis of a risk index that estimates the combined action of biological age and exposure time. Despite the fact that studies in the literature have reached conflicting results, our study highlights a significant drop in attention and memory performances in individuals exposed to aluminium. Finally, we identify a global criterion that summarises the information on the neurocognitive state by applying the nonparametric combination of dependent rankings method (NPC ranking).     

An empirical investigation into the effect of childbearing on economic wellbeing in Europe

This paper investigates the extent childbearing among couples in Europe affects their level of economic well being. We do so by implementing a propensity score matching procedure in combination with a difference-in-difference estimator. Using data from European Community Household Panel Survey (ECHP), we compare how the impact of childbearing on wellbeing varies among countries. We use several measures for wellbeing, including poverty status and various deprivation indices that take into account the multidimensionality of individuals‘ assessment of wellbeing. Not unexpected we find childbearing tend to worsen the economic wellbeing of households, but with important differences in magnitude across countries. In Scandinavian countries the effect is small and rarely significant, it is strong in the UK and also significant in Mediterranean countries. Depending on the measure of wellbeing, we find important differences among countries that are similar in terms of welfare provision.     

The Effect of Changing Sexual, Marital and Contraceptive Behaviour on Conceptions, Abortions, and Births

A model is proposed to estimate the number of conceptions during a single year using scarce survey data, official data on births and abortions for the two years following the survey, and some parameters on contraception failure. The model is fitted for 1979, 1989, 1994 to Puglia, a Southern Italian region with a population of 4 millions. Simulations are also produced.The decrease in births is caused mainly by the decline in wanted births, whereas the decline in abortions is caused by diffusion of the pill, IUD, and condom. The rapid increase in the proportion of never-married women explains the slow decrease in unwanted births and conceptions, compared to the fast decline in wanted ones. This situation is different compared to other Western countries (e.g. France, UK, and USA) where the decline in TFR during the 1960s and 1970s was largely caused by the decline in unwanted fertility, thanks to improved modern contraception and sterilisation.     

The use of different data sources in the analysis of co-authorship networks and scientific performance

Scientific collaboration is usually derived from archival co-authorship data. Several data sources may be examined, but they all have advantages and disadvantages, especially when a specific discipline or community is of interest. The aim of this paper is to explore the effect of the use of three data sources – Web of Science, Current Index to Statistics and nationally funded research projects – on the analysis of co-authorship networks among Italian academic statisticians. Results provide evidence of our hypotheses on distinct collaboration patterns among statisticians, as well as distinct effects of scientist network positions on scientific performance, by both Statistics subfield and data source.     

Testing for Heterogeneity with Categorical Data: Permutation Solution vs. Bootstrap Method

In this article the problem of comparing distributional heterogeneities for categorical variables is addressed. Specifically, the one-sided testing problem for heterogeneity comparisons is considered. For such a problem a bootstrap method is proposed and compared with a permutation method already present in literature. The power behavior of the two methods is compared through a Monte Carlo simulation study. The results of two real applications are shown.     

The Banking Industry in Egypt

This paper examines the structure and performance of the banking industry in Egypt during the period from 2002 to 2009. The Central Bank of Egypt undertook a major banking reform towards a more liberal system. This included the strengthening of bank supervision and regulation and the bank privatization, where it helped to improve market competitiveness and efficiency. Total registered banks’ deposits grew at a CAGR of 11.43% during 2002–2009, reaching LE 848.7 billion at the end of December 2009, while their total credit facilities increased at a CAGR of 10%, reaching LE 793.8 billion.     

A Bayesian non-parametric modeling to estimate student response to ICT investment†

This paper estimates the causal impact of investment in information and communication technologies (ICT) on student performances in mathematics as measured in the Program for International Student Assessment (PISA) 2012 for Spain. To do this we apply a new methodology in this context known as Bayesian Additive Regression Trees that has important advantages over more standard parametric specifications. Results indicate that ICT has a moderate positive effect on math scores. In addition, we analyze how this effect interacts with variables related to school features and student socioeconomic status, finding that ICT investment is especially beneficial for students from a low socioeconomic background.