Comments on “Sums,Products, and Ratios of Non-Central Beta Variables” by Saralees Nadarajah

Brief comments on “Sums, Products, and Ratios of Non-Central Beta Variables” by Saralees Nadarajah, which appeared in Communications in Statistics – Theory and Methods, Volume 34, Issue 1, pp. 89–100.     

Neighborhood Effects in Temporal Perspective

Theory suggests that neighborhood effects depend not only on where individuals live today, but also on where they lived in the past. Previous research, however, usually measured neighborhood context only once and did not account for length of residence, thereby understating the detrimental effects of long-term neighborhood disadvantage. This study investigates the effects of duration of exposure to disadvantaged neighborhoods on high school graduation. It follows 4,154 children in the PSID, measuring neighborhood context once per year from age 1 to 17. The analysis overcomes the problem of dynamic neighborhood selection by adapting novel methods of causal inference for time-varying treatments. In contrast to previous analyses, these methods do not "control away" the effect of neighborhood context operating indirectly through time-varying characteristics of the family, and thus they capture the full impact of a lifetime of neighborhood disadvantage. We find that sustained exposure to disadvantaged neighborhoods has a severe impact on high school graduation that is considerably larger than effects reported in prior research. Growing up in the most (compared to the least) disadvantaged quintile of neighborhoods is estimated to reduce the probability of graduation from 96% to 76% for black children, and from 95% to 87% for nonblack children.     

Child Mortality and Environment in Developing Countries

This paper studies child mortality and fertility in 61 developing countries including the Central Asian Republics (CARs). To control for simultaneity, an estimated value of fertility was used in the mortality equation and a final specification included only exogenous socio-economic, health and environmental variables. We confirm the importance of female literacy in explaining both fertility and mortality, and also find a measure of consumption for the poorest share of the population to be significant, while controlling for nutrition, health expenditure, and income distribution. Incidence of tuberculosis and female agricultural population proxy for environmental impacts, but in spite of these controls, approximately 41% additional mortality was estimated due to living in the CARs. The results fill gaps in the literature: we use a wider range of socio-economic and environmental health variables than previously in an encompassing analysis of mortality and fertility, and find evidence of excessive mortality in the CARs most likely linked to environmental degradation in the region.

Bildungschancen von Grundschülern: Die Bedeutung des Klassen- und Schulkontextes am Übergang auf die Sekundarstufe I

Do context characteristics of class and school have an impact on elementary school pupils’ educational opportunities in addition to the confirmed individual effects of social origin and academic performance? The paper investigates the influence of the contextual performance- and SES-level as well as of the ethnic composition of the context on the probability of (1) obtaining a recommendation for higher secondary schools (Gymnasium) and (2) effectively attending a higher secondary school. To this end, we base our theoretical framework on the distinction between primary and secondary effects, as introduced by Boudon (1974), and extend it by a contextual perspective, as well as the related decisions of parents and teachers. The analyses are based on a survey of all 4^th graders of elementary schools in the city of Wiesbaden (Germany) during the school year 2006/07. The context effects are modelled by using logistic multilevel models. The results show that the affiliation to both school- and class context explains about 10 per cent of the total variance of academic achievement. Additionally, there is evidence that the context effects significantly influence the individual educational opportunities in particular when the individual marks are controlled for (secondary context effects). Furthermore, especially the SES-related context composition influences the educational outcomes when controlling for relevant individual variables. With respect to the accomplished transitions to the Gymnasium, the performance level of the school also has significant impact. Contrary to previous studies, we could not detect any effect of the ethnic composition of the context when SES is controlled for. While there are effects of the class context as well as of the school context with the educational recommendation as dependent variable, only the school context is of relevance concerning the effectively attained school transition.     

The Biodemography of Fertility: A Review and Future Research Frontiers

The social sciences have been reticent to integrate a biodemographic approach to the study of fertility choice and behaviour, resulting in theories and findings that are largely socially-deterministic. The aim of this paper is to first reflect on reasons for this lack of integration, provide a review of previous examinations, take stock of what we have learned until now and propose future research frontiers. We review the early foundations of proximate determinants followed by behavioural genetic (family and twin) studies that isolated the extent of genetic influence on fertility traits. We then discuss research that considers gene and environment interaction and the importance of cohort and country-specific estimates, followed by multivariate models that explore motivational precursors to fertility and education. The next section on molecular genetics reviews fertility-related candidate gene studies and their shortcomings and on-going work on genome wide association studies. Work in evolutionary anthropology and biology is then briefly examined, focusing on evidence for natural selection. Biological and genetic factors are relevant in explaining and predicting fertility traits, with socio-environmental factors and their interaction still key in understanding outcomes. Studying the interplay between genes and the environment, new data sources and integration of new methods will be central to understanding and predicting future fertility trends.     

作为普遍人类现象的批判性思维——中国和美国的视角

本文论述了西方批判性思维的起源和发展,分析了批判性思维对教育、经济和民主的重要作用,概述了批判性思维技能和倾向的定义,比较了中国和西方批判性思维的特点,并期待二者的综合,最后指出了进一步研究批判性思维的两条主要途径。在整个美国和许多其他地方,大学教育的基本目标之一就是教会学生批判性思维。     

On the bivariate negative binomial regression model

In this paper, a new bivariate negative binomial regression (BNBR) model allowing any type of correlation is defined and studied. The marginal means of the bivariate model are functions of the explanatory variables. The parameters of the bivariate regression model are estimated by using the maximum likelihood method. Some test statistics including goodness-of-fit are discussed. Two numerical data sets are used to illustrate the techniques. The BNBR model tends to perform better than the bivariate Poisson regression model, but compares well with the bivariate Poisson log-normal regression model.     

Team adaptation triggers: A categorization scheme

In the present study of the journal of Gruppe. Interaktion. Organisation, the purpose was to identify the types of events that activate team adaptive behavior during goal achievement and to provide a roadmap for future research into how team adaptation responses may differ depending on the demands faced. Two hundred and eight engineering students involved in an eight-week team project, participated in our study. They reported, at three time points, 271 events that triggered their team to change their way of functioning. We applied qualitative content analysis to identify the underlying categories of the collected triggers and identified three main categories of internal (interpersonal dynamics, task-related activities, reaching a milestone), and three main categories of external team adaption triggers (change in resources, interventions, alterations in framework), with various subcategories. Our findings demonstrated that team adaptation triggers can stem from the team’s environment and from the team itself. Furthermore, our results suggested that positively connoted events (e.g. achievement of subgoals) as well as negatively connoted events (e.g. loss of a member) are perceived as relevant team adaptation triggers. Our study opens a new avenue for team adaptation theory and research by providing the first categorization scheme of team adaptation triggers. Future studies can from now provide insight into the relationship between trigger features and team adaptation processes, exploring team adaptation success in various contexts.

     

Households’ preferences for attributes of Conditional Cash Transfer programmes: A choice experiment in Ghana

Conditional cash transfer (CCT) is increasingly being integrated into poverty reduction strategies in developing countries. However, debate remains over key elements of CCT programme design. Using a discrete choice model, this article examines Ghanaian households’ preferences regarding key CCT programme design elements including conditionality, targeting, and payment method. The results revealed a preference for CCT designs that target beneficiaries with limited or no productive capacity and CCT designs that are conditional on beneficiaries either investing in children's human capital or performing communal service, relative to unconditional programmes. Also, direct bank deposit was revealed as the preferred payment mode relative to receipt of cash payments or use of mobile money systems.