Bayesian updating of atmospheric dispersion after a nuclear accident

Summary.  We consider a Bayesian forecasting system to predict the dispersal of contamination on a large scale grid in the event of an accidental release of radioactivity. The statistical model is built on a physical model for atmospheric dispersion and transport called MATCH. Our spatiotemporal model is a dynamic linear model where the state parameters are the (essentially, deterministic) predictions of MATCH; the distributions of these are updated sequentially in the light of monitoring data. One of the distinguishing features of the model is that the number of these parameters is very large (typically several hundreds of thousands) and we discuss practical issues arising in its implementation as a realtime model. Our procedures have been checked against a variational approach which is used widely in the atmospheric sciences. The results of the model are applied to test data from a tracer experiment.     

Attitudes and Risk Perceptions of Stakeholders in a Nuclear Waste Siting Issue

Stakeholders are often regarded as a critically important group in such issues as the siting of nuclear facilities. In this article, stakeholders were identified on the basis of self-reported activities with regard to a nuclear waste siting issue under debate in four communities. Data were obtained in an extensive mailed survey from a total of 2,548 respondents, approximately an equal number from each community. The overall response rate was 43.9%. Some of the results and telephone interviews with a sample of the nonrespondents indicated that the data are reasonably representative of the respective populations. Stakeholder activities were measured by 20 questions and combined with an index of stakeholder activity level, dichotomized at the 90th percentile. Stakeholders were found to have a higher level of education than others, but otherwise they did not differ in demographics. They did not tend to see risks in general as high, but were quite interested and involved in the nuclear waste siting issue. The stakeholder activity level correlated with risk perception and attitudes in the waste siting issue, but with different signs for those who were for and those who were opposed: stakeholders of both types had more extreme views than others, but in different directions. In addition, stakeholder opponents were much more likely to strongly espouse extreme statements regarding the project than were supporters who also were stakeholders. Implications for risk management and communication are discussed.     

On variable selection in generalized linear and related regression models

This paper is concerned with selection of explanatory variables in generalized linear models (GLM). The class of GLM's is quite large and contains e.g. the ordinary linear regression, the binary logistic regression, the probit model and Poisson regression with linear or log-linear parameter structure. We show that, through an approximation of the log likelihood and a certain data transformation, the variable selection problem in a GLM can be converted into variable selection in an ordinary (unweighted) linear regression model. As a consequence no specific computer software for variable selection in GLM's is needed. Instead, some suitable variable selection program for linear regression can be used. We also present a simulation study which shows that the log likelihood approximation is very good in many practical situations. Finally, we mention briefly possible extensions to regression models outside the class of GLM's.     

Worry and Risk Perception

Risk perception is sometimes measured by means of judgments about worry, sometimes as perceived risk more directly. However, perceived level of risk calls for a more intellectual judgment and worry tends to refer to emotional reactions. These two are therefore not the same and need not be strongly correlated. Results reported here show that perceived risk and worry are indeed weakly correlated, both for generalized worry and for more specific measures of worry matched with the same hazard as risk ratings. A distinction is suggested between cognitive, abstract hazards and concrete, sensory hazards, with implications for the worry-perceived risk relationship. It was furthermore found by means of cluster analysis that there were groups of subject displaying different dynamics of risk and worry.     

Negotiating deficiency: Exploring ethnic minority parents' narratives about encountering child welfare services in Norway

Evaluating the participatory opportunities for service users within social welfare institutions is a pressing issue. In this article, we explore a group of ethnic minority parents' experiences with child welfare services (CWS) in Norway. A strong narrative theme was deficiency positioning—how lacking a Norwegian normative set of knowledge and skills challenged the parents' opportunities to participate. We analysed how deficiency positioning was perceived, negotiated, and contested in the parents' accounts, and 4 themes emerged: (a) learning to parent, (b) contesting expert knowledge, (c) learning to be a client, and (d) constructing CWS deficiency. Nancy Fraser's concept of “participatory parity” was applied to explore how current institutional structures may enable and limit parents' participation. The analysis provides insight into agencies and informants' sense‐making processes as well as the diverse resources and strategies that parents draw upon in the CWS encounter. Furthermore, we argue that an interplay between a strong focus on “parenting skills” and bureaucratic and economic structures positions ethnic minority parents as deficient, thus providing powerful mechanisms for marginalization. Implications for case work and institutional levels are discussed.     

A comprehensive workplace intervention and its outcome with regard to lifestyle, health and sick leave: the AHA study

This study is a prospective multicentre cohort study entitled Work and Health in the Processing and Engineering Industries, the AHA Study (AHA is the Swedish abbreviation for the study). Four large workplaces in Sweden participated during the years from 2000 to 2003. The present report has two objectives: (1) to present a comprehensive occupational health intervention programme and (2) to evaluate this programme with a focus on lifestyle (smoking and exercise), health related quality of life (HRQoL) and sick leave. Interventions were provided on an individual and group level, including evidence-based methods for four health/focus areas (individual level) and a group intervention based on a survey-feedback methodology. The analyses in this report were exclusively employed at an organizational level. The proportion of smokers decreased at three companies and the course of the HRQoL was advantageous at two of the companies as compared to a gainfully employed reference group. A significant decrease in sick leave was revealed at one company, whereas a break in an ascending sick-leave trend appeared at a second company as compared to their respective corporate groups. This comprehensive workplace intervention programme appears to have had positive effects on smoking habits, HRQoL and sick leave.