New Bootstrap Applications in Supervised Learning

Some bootstrap and boosting methods for problems related to classification are introduced in this article. The first method chooses better boosting weights by using a bootstrap search algorithm. The second method is a good way to define a classification frontier. A new formulation for boosting in linear discriminant analysis is given. Since in this new formulation the uncertainty is represented by the weighted covariance matrix, it is more appropriate from the conceptual point of view. Simulation results show that the proposed methods perform well in data analysis.     

Mapping Civic Engagement in Later Life: A Scoping Review of Gerontological Definitions and Typology Proposal

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations - Research on older people’s civic engagement has increased significantly in the last two decades, as have policy and...     

On the Determinants of Mortality Reductions in the Developing World

This article presents and critically discusses evidence on the determinants of mortality reductions in developing countries. It argues that increases in life expectancy between 1960 and 2000 were largely independent of improvements in income. The author characterizes the age and cause‐of‐death profile of changes in mortality and assesses what can be learned about the determinants of these changes from the international evidence and from country‐specific studies. Public health infrastructure, immunization, targeted programs, and the spread of less palpable forms of knowledge all seem to have been important factors. Finally, the article suggests that the evolution of health inequality across and within countries is intrinsically related to the process of diffusion of new technologies and to the nature of these new technologies, public or private.     

Father Involvement and Children's Early Learning: A Critical Review of Published Empirical Work from the Past 15 Years

ABSTRACT

Parent involvement research predominantly focuses on the involvement of mothers in children's educational experiences, and rarely speaks to the role of the “other” parent – fathers. Yet, there is building interest in the role that fathers play in children's development, and how this role may be especially salient during early childhood and the transition into formal schooling. This review critically evaluates father involvement literature from 1990 to 2005 within this early childhood population. In particular, it provides systematic evidence that to some degree researchers have been responsive to recent critiques, and lays out a path of sampling, methodological and conceptual challenges still left to be tackled.     

“Isn't it ironic…!?!” Mobility researchers go sedentary: A group auto-ethnography on collective coping and care in pandemic times

We moved places and places moved us, until force majeure detained us on the spot. Signed-up to be hyper-mobile Ph.D.-candidates, we became hyper-reflective pandemic intimates. We moved together into a space that felt safe, OUR safe space. Suspended. Did the pandemic open this door, or had this space always existed, even back in the old days? Probably the latter, although we were not sensitive enough to perceive it, too busy to push the door, too lonesome to CARE. Not attentive to its possibilities, not imaginative of its POWER, too confident to be capable of succeeding alone. Even if we might have secretly wished for this space to exist. The present piece of work, and JOY, might be described by others as a “side-step,” a “hobby project,” a “shadow activity.” For us, it is a recollection of shocks and wonders, a sentience of precious, ephemeral instances that last. We are a group of eight early career researchers who study global mobility and labor migration from a variety of disciplinary perspectives. With prior international mobility experience, we left our previous countries of residence in 2018 to join an EU-funded research project, whilst being located in different European cities. One could classify us, for example, as highly qualified, privileged migrants. The present paper is the outcome of a collaborative, auto-ethnographic study, conducted in 2020, in the midst of the Covid-19 pandemic, when we suddenly were forced not to travel anymore. We got together online every week to “refaire le monde,” and we conducted virtual, dialogical self-interrogations and group reflections. Based on an emic approach, in line with Chang et al. (2013), we applied an iterative process of data collection and analysis. Our weekly conversations naturally emerged as a safe space for exchange and understanding, as we were facing similar situations, despite staying at different places. Suddenly, as the privilege of “always being on the move,” “always socializing and networking” disappeared due to closed borders and pandemic threats, we experienced anxieties and isolation and had to re-evaluate our perceptions on life, work, and international mobility. The very purpose and meaning of our broader research endeavors and employment perspectives suddenly faded away. We realized more than ever before, what it means to us to be allowed to move, to travel freely across continents.     

Is the scheduling task context-dependent? A survey investigating the presence of constraints in different manufacturing contexts

Abstract

Most studies regarding real scheduling constraints only consider the constraints related to the specific manufacturing environment studied, limiting the possibility of drawing general conclusions. A survey of 50 companies was conducted in order to discover which constraints were present and what their relationship was with the scheduling context. This paper investigates which practical scheduling constraints are present in the manufacturing industry and whether the scheduling task is context-dependent. Results of this study show that some practical production constraints are context-dependent.     

An extended Birnbaum–Saunders distribution: Theory,estimation, and applications

Abstract

Birnbaum and Saunders (1969a Birnbaum, Z.W., Saunders, S.C. (1969a). A new family of life distributions. J. Appl. Probab. 6:319–327.[Crossref], [Web of Science ®] , [Google Scholar]) pioneered a lifetime model which is commonly used in reliability studies. Based on this distribution, a new model called the gamma Birnbaum–Saunders distribution is proposed for describing fatigue life data. Several properties of the new distribution including explicit expressions for the ordinary and incomplete moments, generating and quantile functions, mean deviations, density function of the order statistics, and their moments are derived. We discuss the method of maximum likelihood and a Bayesian approach to estimate the model parameters. The superiority of the new model is illustrated by means of three failure real data sets. We also propose a new extended regression model based on the logarithm of the new distribution. The last model can be very useful to the analysis of real data and provide more realistic fits than other special regression models.     

An extension of the gamma distribution

ABSTRACT

The gamma distribution has been widely used in many research areas such as engineering and survival analysis. We present an extension of this distribution, called the Kummer beta gamma distribution, having greater flexibility to model scenarios involving skewed data. We derive analytical expressions for some mathematical quantities. The estimation of parameters is approached by the maximum likelihood method and Bayesian analysis. The likelihood ratio and formal goodness-of-fit tests are used to compare the presented distribution with some of its sub-models and non nested models. A real data set is used to illustrate the importance of the distribution.     

Macroeconomic Uncertainty Through the Lens of Professional Forecasters

ABSTRACT

We analyze the evolution of macroeconomic uncertainty in the United States, based on the forecast errors of consensus survey forecasts of various economic indicators. Comprehensive information contained in the survey forecasts enables us to capture a real-time measure of uncertainty surrounding subjective forecasts in a simple framework. We jointly model and estimate macroeconomic (common) and indicator-specific uncertainties of four indicators, using a factor stochastic volatility model. Our macroeconomic uncertainty estimates have three major spikes has three major spikes aligned with the 1973–1975, 1980, and 2007–2009 recessions, while other recessions were characterized by increases in indicator-specific uncertainties. We also show that the selection of data vintages affects the estimates and relative size of jumps in estimated uncertainty series. Finally, our macroeconomic uncertainty has a persistent negative impact on real economic activity, rather than producing “wait-and-see” dynamics.