Bayesian averaging of classical estimates in asymmetric vector autoregressive models

The estimated vector autoregressive (VAR) model is sensitive to model misspecifications, resulting to biased and inconsistent parameter estimates. This article extends the Bayesian averaging of classical estimates, a robustness procedure in cross-section data, to a vector time-series that is estimated using a large number of asymmetric VAR models. The proposed procedure was applied to simulated data from various forms of model misspecifications. The results of the simulation suggest that, under misspecification problems, particularly if an important variable and moving average (MA) terms were omitted, the proposed procedure gives robust results and better forecasts than the automatically selected equal lag-length VAR model.     

Deterred by debt? Young people,schools and the escalating cost of UK higher education

Popular commentaries lament that reforms to the financing of Higher Education (HE) in the UK will operate as a significant deterrent to HE participation amongst students from less advantaged backgrounds. This view of debt as a deterrent is powerful and exists not only at a societal level, but also, as we show, is present in schools. Our data reveal, however, that these ‘debt commentaries’ play out very differently across schools according to the nature of their catchment and the sorts of views staff hold about pupils in relation to their fear of debt. Furthermore, students’ views on debt largely contradict these popular ‘debt-as-deterrent’ narratives and instead are often characterised by acceptance, ambivalence and at times positive orientations towards the prospect of debt. These findings vividly illuminate both the regional and institutional specificity of staff and student decision making in relation to ‘debt’, hence they have substantial implications for HE funding policy specifically and debates about widening participation in HE more generally, where ensuring greater equity in the scope of choices young people have when it comes to choosing a university is a pressing concern.     

Pharmaceutically-Made Men: Masculinities in Chad’s Emergent Oil Economy

This article explores masculinities and changes in men’s lives in the rural oil fields of Chad during the period of an oil and pipeline project described by the World Bank as a “model” for oil-as-development. In many parts of Africa, private sector investment is concentrated in the extractive industries, especially oil and gas projects. Africa’s emerging oil economies entail new institutional configurations, or what Michael Watts called an “oil complex,” that challenge antecedent norms and forms of identity. In this article, I describe the expectations, desires, and experiences of three distinct groups of men—those who found temporary employment on the project, those who continued to make a living from farming while contending with land expropriation, and those who migrated to oil field towns in search of work—to make three general points about the oil complex and masculinities in Chad. The structure of the global oil industry meant that local men who found jobs on the project could act as breadwinners and patriarchs, but only temporarily; local workers struggled post-employment with their exclusion from the possibilities associated with the project. Men who never found jobs continued to eke out a living from the land, but state-of-the-art policies governing land expropriation led simultaneously to conflict in families and greater economic interdependence among family members. Finally, in the low-media environment of the oil field region, ideas and images about sex, sexuality, and love emanating from the transient and hyper-masculine global oil industry workforce served as models for landless young men who migrated to oil field towns and who, in the absence of work, sought to transform themselves into objects of desire through the mediation of pharmaceuticals.

     

Difference-based Methods for Truncating the Singular Value Decomposition

Given a noisy time series (or signal), one may wish to remove the noise from the observed series. Assuming that the noise-free series lies in some low-dimensional subspace of rank r, a common approach is to embed the noisy time series into a Hankel trajectory matrix. The singular value decomposition is then used to deconstruct the Hankel matrix into a sum of rank-one components. We wish to demonstrate that there may be some potential in using difference-based methods of the observed series in order to provide guidance regarding the separation of the noise from the signal, and to estimate the rank of the low-dimensional subspace in which the true signal is assumed to lie.     

Childbearing Across Partnerships in Australia,the United States,Norway, and Sweden

This article compares mothers’ experience of having children with more than one partner in two liberal welfare regimes (the United States and Australia) and two social democratic regimes (Sweden and Norway). We use survey-based union and birth histories in Australia and the United States and data from national population registers in Norway and Sweden to estimate the likelihood of experiencing childbearing across partnerships at any point in the childbearing career. We find that births with new partners constitute a substantial proportion of all births in each country we study. Despite quite different arrangements for social welfare, the determinants of childbearing across partnerships are very similar. Women who had their first birth at a very young age or who are less well-educated are most likely to have children with different partners. The educational gradient in childbearing across partnerships is also consistently negative across countries, particularly in contrast to educational gradients in childbearing with the same partner. The risk of childbearing across partnerships increased dramatically in all countries from the 1980s to the 2000s, and educational differences also increased, again, in both liberal and social democratic welfare regimes.     

New Data,Strategies, and Insights for Listeria monocytogenes Dose‐Response Models: Summary of an Interagency Workshop, 2011

Listeria monocytogenes is a leading cause of hospitalization, fetal loss, and death due to foodborne illnesses in the United States. A quantitative assessment of the relative risk of listeriosis associated with the consumption of 23 selected categories of ready‐to‐eat foods, published by the U.S. Department of Health and Human Services and the U.S. Department of Agriculture in 2003, has been instrumental in identifying the food products and practices that pose the greatest listeriosis risk and has guided the evaluation of potential intervention strategies. Dose‐response models, which quantify the relationship between an exposure dose and the probability of adverse health outcomes, were essential components of the risk assessment. However, because of data gaps and limitations in the available data and modeling approaches, considerable uncertainty existed. Since publication of the risk assessment, new data have become available for modeling L. monocytogenes dose‐response. At the same time, recent advances in the understanding of L. monocytogenes pathophysiology and strain diversity have warranted a critical reevaluation of the published dose‐response models. To discuss strategies for modeling L. monocytogenes dose‐response, the Interagency Risk Assessment Consortium (IRAC) and the Joint Institute for Food Safety and Applied Nutrition (JIFSAN) held a scientific workshop in 2011 (details available at http://foodrisk.org/irac/events/ ). The main findings of the workshop and the most current and relevant data identified during the workshop are summarized and presented in the context of L. monocytogenes dose‐response. This article also discusses new insights on dose‐response modeling for L. monocytogenes and research opportunities to meet future needs.     

The life-course origins of mastery among older people

In this article, we aim to identify the sources of mastery--the understanding that individuals hold about their ability to control the circumstances of their lives. The sample for our inquiry was drawn from the Medicare beneficiary files of people 65 and older living in Washington, DC, and two adjoining Maryland counties. We find that past circumstances, particularly those reflecting status attainment and early exposure to intractable hardships, converge with stressors experienced in late life to influence elders' level of mastery. The impact of past conditions, however, does not necessarily directly affect the current mastery of older people. Instead, the effect of prior experiences on current mastery is mediated by what we refer to as life-course mastery: one's belief that one has directed and managed the trajectories that connect one's past to the present. Our analyses show that life-course mastery largely serves as the mediating channel through which individuals connect their past to their present.