The dynamic household as a logical concept and its use in demography

Event history models for aggregate units such as households are complicated by the fact that such entities do not have a well-defined identity through time. The difficulties of applying conventional transition-based models to household change are discussed. More generally, what constitutes time and change are also considered. It is argued that many changes occurring within households such as leaving home are better-considered as fuzzy than crisp phenomena. An alternative perspective based on household change considered as an evolving network is proposed. The implications for sample designs which are designed to track explicithousehold dynamics (such as the Panel Study on Income Dynamics) are discussed. The ways in which particular forms of analysis come to dominate the scientific literature, including those for analysing household change is discussed in relation to non-linear dynamic models. Finally, it is argued that there would be considerable benefits if insights available from the physical, mathematical and biological sciences were to be more widely incorporated within technical demography.Les modèles d'analyse biographique d'unités agrégées, telles que les ménages, sont complexes, car ces entités ne peuvent être définies avec précision au cours du temps. Nous discutons ici les difficultés d'appliquer les modèles habituels basés sur des transitions, aux changements connus par les ménages. Plus généralement, nous analysons ce qui constitue «le temps» et le «changement». Nous montrons ainsi que de nombreux changements connus par les ménages, tels que la décohabitation, sont mieux saisis comme des évévements «flous» plutôt que comme des événements ponctuels. Nous proposons dès lors une autre perspective, basée sur les changements survenus dans des réseaux en évolution. Nous en discutons les implications sur les méthodes d'échantillonnage destinées à tracer l'évolution explicite des ménages (telles que l'étude par panel sur l'évolution des revenus). Les façons selon lesquelles certaines formes d'analyse en viennent à avoir une position dominante dans la littérature scientifique, y compris celles qui permettent l'analyse des changements dans les ménages, sont discutées en liaison avec les modèles dynamiques non-linéaires. Finalement, nous montrons qu'il y a des avantages importants à ce que des approches suivies dans les sciences physiques, mathématiques et biologiques, soient plus largement introduites dans les techniques d'analyse démographique.     

II Planning the care environment

This article reviews the experience of a two year post-graduate CQSW course in organising the first year placement as a cluster in which six or seven students are placed in different social work agencies but in the same geographical area. It outlines the advantages of this model of placement planning and practice teaching for students, practice teachers, student units, and college tutors. Particular attention is drawn to the support and stability offered to students and to the opportunity to demonstrate links between theory and practice in the teaching of community social work. It is suggested that this model may provide one way in which student units might develop as training resources for the local area, and help the development of closer collaboration between agencies and colleges.     

The effects of children’s proximity‐seeking to maternal attachment figures during mild stress exposure on mood and physiological responses: An experimental study

In this study we investigated the effects of seeking versus avoiding proximity to mother on children’s emotional recovery from a stressor. Sixty children 9–12 years underwent a moodinduction procedure and were randomly assigned to seek proximity from or avoid an image of their mothers. The effect of this manipulation on children’s self‐reported negative emotions, skin conductance and heart rate variability (respiratory sinus arhythmia) was assessed. Higher levels of attachment anxiety were linked to more self‐reported sadness when children had to avoid mother, but no evidence for such an effect was found on a physiological level. For avoidant attachment, a similar pattern of results emerged, but both for self‐reported sadness and skin conductance.     

The effect of artificial lighting on the arrival time of birds using garden feeding stations in winter: A missed opportunity?

The proliferation of artificial lighting at night is one of the key anthropogenic changes associated with urbanised areas as well as some non-urban areas. Disruption to natural light/dark regimes can have considerable effects on the timing of different behaviours of birds, particularly during the breeding season. However, the effect of artificial lights on the timing of behaviours during winter has received relatively little attention, despite the fact that time partitioning of foraging can have implications for avian winter survival. In this study, we assess at a landscape scale during winter, whether birds arrive at feeding stations earlier in areas with increased levels of artificial lighting using data from a citizen science project. Arrival times of the ten most commonly recorded species were associated with a combination of the density of artificial lights, temperature, rainfall and urban land cover. We found no evidence that birds advance the onset of foraging in gardens with more artificial lights nearby; contrary to our prediction, birds generally arrived later into these areas. This is possibly a response to differences in food availability or predation risk in areas with more artificial lights. We conclude that artificial light at night may not be as important for driving the timing of foraging behaviour in winter as previously thought, but it remains to be seen whether this represents a missed opportunity to extend the foraging period or an adaptive response.     

B. Enjolras and K. H. Sivesind (eds): Civil Society in Comparative Perspective

VOLUNTAS: International Journal of Voluntary and Nonprofit Organizations -     

Great Expectations: Voluntary Sports Clubs and Their Role in Delivering National Policy for English Sport

Voluntary sports clubs (VSCs) account for about a quarter of all volunteering in England. The volunteers work in a mutual aid, self-production, self-consumption system whose main purpose is identifying and nurturing high-level performers. But the new HMG/Sport England strategies leading to London 2012 expects volunteers to make a major contribution to sustaining and extending participation. The study utilized six focus group sessions with a total of 36 officials and members of 36 clubs across the six counties of Eastern England to assess whether and to what extent government policy objectives can be delivered through the voluntary sector. The study focused on the perceptions and attitudes of club members about being expected to serve public policy and the current pressures they and their clubs face. The results lead the authors to question the appropriateness, sensitivity, and feasibility of current sport policy, particularly the emphasis on VSCs as policy implementers.     

Multichannel electroencephalographic analyses via dynamic regression models with time-varying lag–lead structure

Multiple time series of scalp electrical potential activity are generated routinely in electroencephalographic (EEG) studies. Such recordings provide important non-invasive data about brain function in human neuropsychiatric disorders. Analyses of EEG traces aim to isolate characteristics of their spatiotemporal dynamics that may be useful in diagnosis, or may improve the understanding of the underlying neurophysiology or may improve treatment through identifying predictors and indicators of clinical outcomes. We discuss the development and application of non-stationary time series models for multiple EEG series generated from individual subjects in a clinical neuropsychiatric setting. The subjects are depressed patients experiencing generalized tonic–clonic seizures elicited by electroconvulsive therapy (ECT) as antidepressant treatment. Two varieties of models—dynamic latent factor models and dynamic regression models—are introduced and studied. We discuss model motivation and form, and aspects of statistical analysis including parameter identifiability, posterior inference and implementation of these models via Markov chain Monte Carlo techniques. In an application to the analysis of a typical set of 19 EEG series recorded during an ECT seizure at different locations over a patient's scalp, these models reveal time-varying features across the series that are strongly related to the placement of the electrodes. We illustrate various model outputs, the exploration of such time-varying spatial structure and its relevance in the ECT study, and in basic EEG research in general.     

Bayesian Dynamic Factor Models and Portfolio Allocation

We discuss the development of dynamic factor models for multivariate financial time series, and the incorporation of stochastic volatility components for latent factor processes. Bayesian inference and computation is developed and explored in a study of the dynamic factor structure of daily spot exchange rates for a selection of international currencies. The models are direct generalizations of univariate stochastic volatility models and represent specific varieties of models recently discussed in the growing multivariate stochastic volatility literature. We discuss model fitting based on retrospective data and sequential analysis for forward filtering and short-term forecasting. Analyses are compared with results from the much simpler method of dynamic variance-matrix discounting that, for over a decade, has been a standard approach in applied financial econometrics. We study these models in analysis, forecasting, and sequential portfolio allocation for a selected set of international exchange-rate-return time series. Our goals are to understand a range of modeling questions arising in using these factor models and to explore empirical performance in portfolio construction relative to discount approaches. We report on our experiences and conclude with comments about the practical utility of structured factor models and on future potential model extensions.