Genetic influence on age at first birth of female twins born in the UK, 1919–68

Using a sample of monozygotic (945, 42?per cent) and dizygotic (1,329, 58?per cent) twin pairs born 1919–68 in the UK, we applied innovative tobit models to investigate genetic and environmental influences on age at first birth (AFB). We found that a substantial part (40?per cent) of the variation in AFB is caused by latent family characteristics. Genetic dispositions (26?per cent) play a more important role than the shared environment of siblings (14?per cent), with the non-shared environment/measurement error having the strongest influence (60?per cent). Like previous studies, this study reveals marked changes in estimates over time, and supports the idea that environmental constraints (war or economic crisis) suppress and normative freedom (sexual revolution) promotes the activation of genetic predispositions that affect fertility. We show that the exclusion of censored information (i.e., on the childless) by previous studies biased their results.

Supplementary material for this article is available at: http://dx.doi.org/10.1080/00324728.2015.1056823     

Immigrants in the UK and in West Germany –Relative income position,income portfolio,and redistribution effects

Based on data from the BHPS and the SOEP, we analyse the economic performance of various ethnic groups in the UK and West Germany, as well as the effects of income redistribution on these populations. Taking the indigenous population of each country as the reference category, we find that, as a whole, the non-indigenous population in the UK fares much better than the immigrant population in Germany. However, the range of economic performance across different ethnic groups in the UK is much larger than that in Germany. The German corporatist welfare system is characterised by much stronger redistribution effects than the liberal UK one. Consequently, the relatively low-performing immigrant population in Germany profits more from the redistribution system than immigrants with similar socio-economic attributes in the UK.All correspondence to Felix Büchel. Responsible editor: Christoph M. Schmidt     

Promoting workplace‐based training to fight youth unemployment in three EU countries: Different strategies,different results?

During the economic crisis, youth unemployment grew exponentially in many European countries. It was argued that countries with a high level of firm involvement in the provision of initial vocational training were better equipped to address this problem. Boosting workplace‐based training was therefore seen as the right strategy to tackle unemployment. Using Denmark, Spain and the UK as case studies, this article analyses how countries with different skill formation systems have improved this type of training. While the UK reinforced the voluntaristic character of its training regime, Denmark improved the quality of its vocational education, and Spain made reforms to the training and apprenticeship contract. Interestingly, the countries achieved different results. To explain this divergence, it is argued that while the reforms made in the UK and Denmark were compatible with the national institutions and coordination mechanisms, this was not the case in Spain, where reforms were implemented in a non‐complementary way. Key Practitioner Message:

• After the economic crisis it was argued that countries with a high level of firm involvement in the provision of initial VET were better equipped to fight youth unemployment.
• The study analysed how countries with different skill formation systems improved this type of training and assessed their relative success.
• The article shows that when implementing reforms policy makers must take into account the institutions and mechanisms of coordination that prevail in each country. Otherwise, reforms may be unsuccessful.

     

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.     

Managing Electricity Peak Loads in Make‐To‐Stock Manufacturing Lines

In this article, we study the control of stochastic make‐to‐stock manufacturing lines in the presence of electricity costs. Electricity costs are difficult to manage because unit costs increase with the total load, that is, the amount of electricity needed by the manufacturing line at a certain point in time. We demonstrate that standard methods for controlling manufacturing lines cannot be used and that standard analytic results for stochastic manufacturing lines do not hold in the presence of electricity costs. We develop a control policy that balances electricity costs with inventory holding and backorder costs. We derive closed‐form expressions and analytic properties of the expected total cost for manufacturing lines with two workstations and demonstrate the accuracy and robustness of the policy for manufacturing lines with more than two workstations. The results indicate that avoiding electricity peak loads requires additional investment in manufacturing capacity and higher inventory and backorder costs. Our approach also applies to companies which aim at reducing their carbon emissions in addition to their operating costs.     

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.     

Education and Roma Children in the Basque Region of Spain

The European Union and those countries that make up the region of South-eastern Europe are built on the pillars of a multicultural society, with different languages, cultures, religions and ethnic groups. This diversity gives rise to various kinds of conflicts. The way in which we resolve these will determine the kind of future we can create for next generations. In this paper, we look at the situation of Roma and Educational provisions for Roma in the Basque region of Spain. It is clear that improvements are being made, but that much work is still necessary. Too few Roma children succeed at the moment in the Spanish and Basque educational systems. We use the case study of one school, the La Esperanza School, to highlight opportunities and barriers to effectively addressing the issue of Roma education.     

Statistical control charts for shifted generalized poisson distribution

Summary The use of shifted (or zero-truncated) generalized Poisson distribution to describe the occurrence of events in production processes is considered. The methods of moments and maximum likelihood are proposed for estimating the parameters of shifted generalized Poisson distribution. Control charts for the total number of events and for the average number of events are developed. Finally, a numerical example is used to illustrate the construction of control charts.     

A computational analysis of the tournament equilibrium set

A recurring theme in the mathematical social sciences is how to select the “most desirable” elements given a binary dominance relation on a set of alternatives. Schwartz’s tournament equilibrium set (TEQ) ranks among the most intriguing, but also among the most enigmatic, tournament solutions proposed so far. Due to its unwieldy recursive definition, little is known about TEQ. In particular, its monotonicity remains an open problem to date. Yet, if TEQ were to satisfy monotonicity, it would be a very attractive solution concept refining both the Banks set and Dutta’s minimal covering set. We show that the problem of deciding whether a given alternative is contained in TEQ is NP-hard, and thus does not admit a polynomial-time algorithm unless P equals NP. Furthermore, we propose a heuristic that significantly outperforms the naive algorithm for computing TEQ.