Nonparametric Estimation of the Average Availability

The average availability of a repairable system is the expected proportion of time that the system is operating in the interval [0, t]. The present article discusses the nonparametric estimation of the average availability when (i) the data on ‘n’ complete cycles of system operation are available, (ii) the data are subject to right censorship, and (iii) the process is observed upto a specified time ‘T’. In each case, a nonparametric confidence interval for the average availability is also constructed. Simulations are conducted to assess the performance of the estimators.     

Analysis of the changing relationship between peer acceptance and academic achievement in adolescents / Análisis de la relación variable entre la aceptación entre iguales y el rendimiento académico de los adolescentes

Peer interactions in the context of group-level relationships have significant consequences on social adjustment across the lifespan of children and adolescents. Indeed, peer relations change systematically with individuals’ development. This study examined the effect of positive peer interactions measured as peer acceptance on academic achievement during the adolescence developmental stage. Participants were 766 students aged 11–16 years old. Adolescents completed a sociometric measure of peer acceptance. Academic achievement data were obtained from students’ report card grades. Regression analyses indicated that peer acceptance predicted academic achievement, and also a moderation effect was found displaying a higher impact of peer acceptance on academic achievement for younger adolescents than for older adolescents. It is suggested that improving peer relationships within the group, especially at early adolescence, can be a target of intervention to improve academic functioning at school.     

Single motherhood and children's health

This analysis employs the recently released Hispanic Health and Nutrition Examination Survey (hispanic HANES) and the National Health and Nutrition Examination Survey II (NHANES) to determine the effect of a mother's marital status on her report of her child's health for Mexican-American, black, and non-Hispanic white children aged 6 months to 11 years. The results reveal that single mothers report poorer overall physical health for their children than do mothers in intact marriages. Several social and cultural factors, including marital status, acculturation, and income, affect the accuracy of mother's assessments. The analysis also documented the extensive dependence of single mothers, especially minority-group mothers, on public programs. In summary, a mother's report of her child's health is the result of a complex interaction of cultural, demographic, and social class factors. This analysis revealed that marital status operates differently for 3 racial and ethnic groups, and that poverty and the stresses associated with single motherhood decrease levels of reported health for children. Analysis of a matched sample of Mexican-American children and their mothers revealed that, net of physician's assessment of a child's health, a mother's depression score is among the most significant predictors of her assessment of her child's health.     

The simulation of industrial robot systems

This paper describes the GRASP computer aided design system for modelling and evaluating industrial robot workplaces. GRASP satisfies a range of simulation needs within the context of designing, implementing and operating industrial robotic systems. The GRASP software may be used to investigate robots operating by themselves or, more likely, as part of an integrated cell. Facilities within GRASP assist workplace layout, position and velocity evaluations, clash detection and co-ordination between items. A robot library exists and is being extended, and an embryo off-line programming facility has been used under restricted conditions. GRASP has been used to help solve a wide range of practical industrial robot problems and has proved itself technically, and also as an educational tool, by showing how a proposed system would operate. The paper describes the facilities within GRASP.     

Kritische Ereignisse und private Überschuldung

This article investigates in how far critical life events (e.g. unemployment) as well as financial shocks triggered by such events affect the probability of private households to enter over-indebtedness (shock hypothesis). Second, we examine if the effect of such events is mitigated by coping measures set by the household after the critical event and/or financial shock has occurred (coping hypothesis). Third, we test if the effect of critical events/financial shocks also depends on the household structure and its financial circumstances (vulnerability hypothesis). To test these hypotheses, we use panel data from the ECHP (1995–2001) and EU-SILC (2004–2008) for Austria. We estimated multivariate panel regression models which allow controlling for unobserved, time-invariant factors. Results suggest that financial shocks have a positive and significant effect on the likelihood of becoming over-indebted, while we did not find evidence for a direct effect of critical life events on over-indebtedness after controlling for unobserved time-constant factors in the fixed effects regression specifications. Regarding the coping hypothesis, evidence for a diminishing moderation effect of cost-saving strategies by households is weak but robust. Similarly, there is some evidence to support the vulnerability hypothesis—but only for some of the indicators chosen to reflect household vulnerability. Overall, our results indicate that causes to enter over-indebtedness cannot be exclusively reduced to either exogenous shocks or behavioral factors.     

The Gender Wage Gap and Poverty in Colombia

Abstract. Using 19 years of cross‐section wage data, we look at the trend of the ratio of male to female wages in Colombia. First, we observe a long‐term trend towards an increase in the gender wage gap that may be related to new labor regulations giving more protection to women and thereby raising the cost of female employment for firms. Second, we measure the impact on poverty of the increasing gap by producing estimates of the income distribution for the subsequent years had the wage gap remained at the low level it used to be in the early 1990s. As mainly low‐skilled women suffered from the increase in the wage gap, we find that the phenomenon contributed to an overall increase in poverty during the decade.     

How do we capture 15 years of complex and meaningful data about young people's lives?

Abstract

This paper describes the development of a method of data collection, which captures the complexity of living situations, family dynamics and key life events of teenagers. This ‘Life History Calendar’ was adapted from earlier life history calendar methods for a multidisciplinary intergenerational study. The new calendar is able to record details of 15 years of teenage participants’ lives and can be administered to teenagers and their parents to show changes over individual lives and difference between individuals in a cohort. Referring to some preliminary data, we show that the calendar is a practical and effective method of data collection, which will be useful to researchers and practitioners working with young people and their families.     

Diaspora,Community and Communication: Internet Use in Transnational Haiti

Abstract With its capacity to link many people interactively across great distances, the Internet seems to be the ultimate tool for dispersed ethnic groups wishing to sustain identity in an ‘alien’ land and work in solidarity with those facing challenges at ‘home’. Some theorists speak of the creation of diasporic public spheres arising from creative use of Internet technologies. Nevertheless, scholars working in this area rarely embed their analyses within existing work on the public sphere. In the present study I use insights from public sphere theory to evaluate participants' use of a Haiti Global Village forum. After examining Haiti Global Village, I conclude that such forums offer needed space for civic deliberation and provide a valuable infrastructure for networking. Participants' difficulty in translating these assets into an off‐line project, however, highlights the importance of place‐based social ties. Consideration of the experience of other Haitian forums reinforces the importance of such ties.     

Minimum Φ-divergence estimator in logistic regression models

A general class of minimum distance estimators for logistic regression models based on the ϕ-divergence measures is introduced: The minimum ϕ-divergence estimator, which is seen to be a generalization of the maximum likelihood estimator. Its asymptotic properties are studied as well as its behaviour in small samples throught a simulation study. This work was supported partially by Grant DGI (BMF2003-00892).