WinBUGS - A Bayesian modelling framework: Concepts,structure, and extensibility

WinBUGS is a fully extensible modular framework for constructing and analysing Bayesian full probability models. Models may be specified either textually via the BUGS language or pictorially using a graphical interface called DoodleBUGS. WinBUGS processes the model specification and constructs an object-oriented representation of the model. The software offers a user-interface, based on dialogue boxes and menu commands, through which the model may then be analysed using Markov chain Monte Carlo techniques. In this paper we discuss how and why various modern computing concepts, such as object-orientation and run-time linking, feature in the software's design. We also discuss how the framework may be extended. It is possible to write specific applications that form an apparently seamless interface with WinBUGS for users with specialized requirements. It is also possible to interface with WinBUGS at a lower level by incorporating new object types that may be used by WinBUGS without knowledge of the modules in which they are implemented. Neither of these types of extension require access to, or even recompilation of, the WinBUGS source-code.     

Letters: A Critique of Meyerson's “Population,Development and Global Warming: Averting the Tragedy of the Climate Commons”

Population and Environment -     

Some macroeconomic aspects of global population aging

Across the demographic transition, declining mortality followed by declining fertility produces decades of rising support ratios as child dependency falls. These improving support ratios raise per capita consumption, other things equal, but eventually deteriorate as the population ages. Population aging and the forces leading to it can produce not only frightening declines in support ratios but also very substantial increases in productivity and per capita income by raising investment in physical and human capital. Longer life, lower fertility, and population aging all raise the demand for wealth needed to provide for old-age consumption. This leads to increased capital per worker even as aggregate saving rates fall. However, capital per worker may not rise if the increased demand for wealth is satisfied by increased familial or public pension transfers to the elderly. Thus, institutions and policies matter for the consequences of population aging. The accumulation of human capital also varies across the transition. Lower fertility and mortality are associated with higher human capital investment per child, also raising labor productivity. Together, the positive changes due to human and physical capital accumulation will likely outweigh the problems of declining support ratios. We draw on estimates and analyses from the National Transfer Accounts project to illustrate and quantify these points.     

Facing up to uncertain life expectancy: The longevity fan charts

This article uses longevity fan charts to represent the uncertainty in projections of future life expectancy. These fan charts are based on a mortality model calibrated on mortality data for English and Welsh males. The fan charts indicate strong upward sloping trends in future life expectancy. Their widths indicate the extent of uncertainty in these projections, and this uncertainty increases as the forecast horizon lengthens. Allowing for uncertainty in the parameter values of the model adds further to uncertainty in life expectancy projections. The article also illustrates how longevity fan charts can be used to stress-test longevity outcomes.     

A Comparison of Affect Ratings Obtained with Ecological Momentary Assessment and the Day Reconstruction Method

Measurement of affective states in everyday life is of fundamental importance in many types of quality of life, health, and psychological research. Ecological momentary assessment (EMA) is the recognized method of choice, but the respondent burden can be high. The day reconstruction method (DRM) was developed by Kahneman and colleagues (Science, 2004, 306, 1776–1780) to assess affect, activities and time use in everyday life. We sought to validate DRM affect ratings by comparison with contemporaneous EMA ratings in a sample of 94 working women monitored over work and leisure days. Six EMA ratings of happiness, tiredness, stress, and anger/frustration were obtained over each 24 h period, and were compared with DRM ratings for the same hour, recorded retrospectively at the end of the day. Similar profiles of affect intensity were recorded with the two techniques. The between-person correlations adjusted for attenuation ranged from 0.58 (stress, working day) to 0.90 (happiness, leisure day). The strength of associations was not related to age, educational attainment, or depressed mood. We conclude that the DRM provides reasonably reliable estimates both of the intensity of affect and variations in affect over the day, so is a valuable instrument for the measurement of everyday experience in health and social research.     

Looking at engagement and outcome from the perspectives of child protection workers and parents

This paper reports a study that sought to understand what facilitates engagement between parents and child protection workers and to ascertain the relationship between such engagement and intervention outcome. Quantitative and qualitative data were gathered through personal interviews with 131 worker-parent dyads (workers and corresponding parents receiving service) from 11 child protection agencies in Ontario, Canada. Measures included scales for engagement, parental well-being (depression and stress), and worker well-being (burnout, job satisfaction, stress). Outcome measures included perception of child safety, changed parenting practices and satisfaction. A relationship was found between workers' perception of parent engagement and parents' perception of their own engagement, as well as between the perceptions that workers and parents had around their own respective engagement. Workers who were satisfied with service outcomes were significantly more engaged than those who were unsatisfied. Parents thinking that their children were safer as a result of intervention were significantly more engaged than parents who thought that their children were less safe. The strongest reason given by parents for positive change was being able to trust their worker (p < .001) and believing that their worker was knowledgeable about parenting (p < .01). Qualitative data suggested that parents valued experienced workers because they thought such workers could better understand their problems and how to deal with them. Correspondingly, workers felt that experience enabled them to better understand clients' problems and provide more effective support. No relationship was found between parent engagement and parental depression or stress, but the mean depression score for parents placed them at risk of clinical depression. There was a negative correlation between worker stress and engagement. The study demonstrates that engagement between clients and workers is related to positive outcomes (as reported by workers and parents) and supports the contention that promoting engagement is integral to a successful child protection intervention.     

Evaluating local food programs: The case of Select Nova Scotia

This study evaluated the effectiveness of the buy local food program Select Nova Scotia; a government program with the goal to increase awareness and consumption of Nova Scotia produced and processed agri-food products by Nova Scotians and visitors. The evaluation methodology was based on prior evaluation resources and local food consumer research. Data were gathered through a web panel survey; 877 respondents completed the survey in June 2010. The results suggest that the program is reaching a wider audience than just those predisposed to local food initiatives. In addition, awareness of Select Nova was related to perceptions of local benefits and barriers, as well as purchase motivation and behavior. Respondents who were aware of Select Nova Scotia rated societal benefits as more important and viewed location and price as less of a barrier; they were also more likely to be highly motivated to purchase local foods. This study also informs results found in previous consumer research studies and identifies marketing opportunities to enhance the effectiveness of local food programs. The results suggest that societal benefits might be used as a way to differentiate products with similar attributes.     

Changes in Parent,Sibling, and Peer Support During the Transition to Young Adulthood

Longitudinal trajectories of parent, sibling, and peer support during the transition to young adulthood were compared among 600 participants (51.1% female) from Asian, European, and Latin American backgrounds. Participants completed questionnaires at 12th grade, 2 and 4 years after high school. Results indicated that parent support increased across this period for participants from European backgrounds but remained stable for participants from Asian and Latin American backgrounds. Peer and sibling support remained relatively stable. Supports had specific implications for self‐esteem and depressive mood. On average, young adults with higher levels of support reported greater expectations to reciprocate support within the family. Together, these findings highlight the changing dynamics of family and friends during the transition to young adulthood.