Uncertainty Quantification in the Ensemble Kalman Filter

The ensemble Kalman filter (EnKF) provides an approximate, sequential Monte Carlo solution to the recursive data assimilation algorithm for hidden Markov chains. The challenging conditioning step is approximated by a linear updating, and the updating weights, termed Kalman weights, are inferred from the ensemble members. The EnKF scheme is known to provide unstable predictions and to underestimate the prediction intervals, and even sometimes to diverge. The underlying cause for these shortcomings is poorly understood. We find that the ensemble members couple in the conditioning procedure and that the coupling increase multiplicatively in the recursive conditioning steps. Under reasonable Gauss‐independence assumptions, exact expressions for this correlation are developed. Moreover, expressions for the precision of the predictions and the downward bias in the empirical variance introduced in one conditioning step are found. These results are confirmed by a Gauss‐linear simulation study. Furthermore, we quantitatively evaluate an alternative, improved EnKF scheme on the basis of transformations of ensemble members under the same Gauss‐independent assumptions. The scheme is compared with the frequently used ensemble inflation scheme.     

In search of ‘The Family’– analysis of the 1981 United Kingdom Census: a research note

This article reviews previous estimates of the frequency of ‘normal families’ ¹ 1 For a detailed discussion of why terms related to ‘family’ are set within quotation marks, see Bemardes (1981, 1985a, 1985b, 1986). Briefly, the intention is to bracket off such terms to indicate that they are part of everyday usage and are not, in themselves, analytic categories appropriate to the sociological enterprise.
in the UK and USA. Using evidence from the 1981 UK Census it is found that ‘normal families’ account for a very small percentage of all ‘families’ in England and Wales. No single central type of ‘family’ exists and there is therefore an urgent need to develop theoretical approaches which address this issue.     

Self-Esteem Within the Work and Organizational Context: A Review of the Organization-Based Self-Esteem Literature

On numerous occasions it has been suggested that an individual’s self-esteem, formed around work and organizational experiences, plays a significant role in determining employee motivation, work-related attitudes and behaviors. We review more than a decade of research on an organization-based conceptualization of self-esteem. It is observed that sources of organization structure, signals about worth from the organization, as well as, success-building role conditions predict organization-based self-esteem. In addition, organization-based self-esteem is related to job satisfaction, organizational commitment, motivation, citizenship behavior, in-role performance, and turnover intentions, as well as, other important organization-related attitudes and behaviors. Explanations for these effects and directions for future research are discussed.     

‘Creating NHS Local’: The Relationship between English Local Government and the National Health Service

Following recent reforms of both local government and the National Health Service, there is significant emphasis in both services on improving inter‐agency collaboration, user involvement and strategic commissioning. In response, this article reviews historical debates about the relationship between local government and health care, before arguing that these two ‘partners’ need each other now more than ever. If local government is to be a ‘place‐shaper’, then it needs significant influence over local health services, while the NHS needs to learn from the best of local government if it is to gain sufficient local legitimacy to take the difficult decisions it needs to take. Against this background, the article reviews different options for future joint working, exploring various options for enacting a new relationship between local government and the NHS.     

Part of the Problem or Part of the Solution? The Role of Care Homes in Tackling Delayed Hospital Discharges

As part of current UK policies to reduce the number of delayedhospital discharges, a number of commentators have identifiedan alleged crisis in the care home market as one of key contributingfactors. With local authorities under pressure to cut costs,it is argued, the number of care homes is reducing, and delaysin hospital can often result. Behind this diagnosis is a seriesof assumptions about the role and nature of care home provision,the appropriateness of this form of service for many older people,and the need for more care homes to reduce the number of hospitaldelays. In order to explore and critique these assumptions,this paper reviews the role of care homes in tackling delayeddischarges, and argues the need for fewer and different carehome placements rather than more of this type of provision.     

Planning participation in public decision making

By posing as specialists in forecasting the future, by arguing the “inevitability of technological progress, and by hiding behind the skirts of public officials, planners in the public sector seek to exercise power without responsibility—power to determine the shape of life for the rest of us. The author attacks this myth of the all- seeing planner and in the process seeks to demolish some of the planners' unwarranted assumptions about “the year 2000”, the future of technology, the affluent society, the age of leisure, etc.     

Ecological regression analysis of environmental benzene exposure and childhood leukaemia: sensitivity to data inaccuracies, geographical scale and ecological bias

Benzene is classified as a group 1 human carcinogen by the International Agency for Research on Cancer, and it is now accepted that occupational exposure is associated with an increased risk of various leukaemias. However, occupational exposure accounts for less than 1% of all benzene exposures, the major sources being cigarette smoking and vehicle exhaust emissions. Whether such low level exposures to environmental benzene are also associated with the risk of leukaemia is currently not known. In this study, we investigate the relationship between benzene emissions arising from outdoor sources (predominantly road traffic and petrol stations) and the incidence of childhood leukaemia in Greater London. An ecological design was used because of the rarity of the disease, the difficulty of obtaining individual level measurements of benzene exposure and the availability of data. However, some methodological difficulties were encountered, including problems of case registration errors, the choice of geographical areas for analysis, exposure measurement errors and ecological bias. We use a Bayesian hierarchical modelling framework to address these issues, and we investigate the sensitivity of our inference to various modelling assumptions.