A note on deriving rank-dependent utility using additive joint receipts

Luce and Fishburn (1991) derived a general rank-dependent utility model using an operation ⊕ of joint receipt. Their argument rested on an empirically supported property (now) calledsegregation and on the assumption that utility is additive over ⊕. This note generalizes that conclusion to the case where utility need not be additive over ⊕, but rather is of a more general form, which they derived but did not use in their article. Tversky and Kahneman (1992), conjecturing that the joint receipt of two sums of money is simply their sum, criticized that original model because ⊕=+ together with additive utility implies the unacceptable conclusion that the utility of money is proportional to money. In the present generalized theory, if ⊕=+, utility is a negative exponential function of money rather than proportional. Similar results hold for losses. The case of mixed gains and losses is less well understood.     

Institutional Diversity and Performance in African Cotton Sectors

This article analyses the performance of cotton sectors across East, Southern, and West Africa, paying particular attention to the wide diversity of institutional arrangements that they now exhibit. It finds strong support for earlier contentions regarding trade‐offs between competition and coordination, and between the roles of public and private sectors. New insights provide concrete and context‐specific guidance to policy‐makers and stakeholders regarding the key challenges they will face and the risks they will need to manage as they work to improve productivity and ensure an equitable division of benefits within cotton sectors.     

Global standards for social work education and training

This paper explores the ways in which social workers can be helped to acquire the wider understanding of relevant legal frameworks which is currently necessary for child-centred practice, given the influence of an ecological perspective on such practice. It arises from the development of a module on child care social work and the community for the Post Qualifying Child Care Award by members of the Law and Social Work Departments at Brunel University. The authors believe that to reach beyond a tokenistic acknowledgement of the ecological perspective requires an understanding and experience of the complex layers which make up the widening and complex social worlds of the child. The paper explains how social workers were encouraged to appreciate both the ever-widening circles of potentially relevant law and the different roles through which law operates. It concludes that a deeper engagement with the legal implications of an ecological dimension to practice would make such practice more effective and would also help combat social exclusion and discrimination.     

‘The cloak of competence’: Assessment dilemmas in social work education

In the face of administrative and pedagogic changes in professional social work training, educators and trainers face considerable uncertainty. Key dilemmas concern what is meant by competence, and how far it is possible to identify and reconcile technical and ideological competencies. This paper uses empirical material from a semi-participant study to explore the relevance of the concept ‘cloak of competence’, with reference to the behaviour of tutors and practice teachers. It suggests that excessive or continuous uncertainty generates avoidance or coping strategies, which lead to a resolution by the achievement of an appearance of competence. The consequences of these processes for staff development are then briefly considered.     

Probabilistic Reliability Modeling for Oil Exploration & Production (E&P) Facilities in the Tallgrass Prairie Preserve

The aging domestic oil production infrastructure represents a high risk to the environment because of the type of fluids being handled (oil and brine) and the potential for accidental release of these fluids into sensitive ecosystems. Currently, there is not a quantitative risk model directly applicable to onshore oil exploration and production (E&P) facilities. We report on a probabilistic reliability model created for onshore exploration and production (E&P) facilities. Reliability theory, failure modes and effects analysis (FMEA), and event trees were used to develop the model estimates of the failure probability of typical oil production equipment. Monte Carlo simulation was used to translate uncertainty in input parameter values to uncertainty in the model output. The predicted failure rates were calibrated to available failure rate information by adjusting probability density function parameters used as random variates in the Monte Carlo simulations. The mean and standard deviation of normal variate distributions from which the Weibull distribution characteristic life was chosen were used as adjustable parameters in the model calibration. The model was applied to oil production leases in the Tallgrass Prairie Preserve, Oklahoma. We present the estimated failure probability due to the combination of the most significant failure modes associated with each type of equipment (pumps, tanks, and pipes). The results show that the estimated probability of failure for tanks is about the same as that for pipes, but that pumps have much lower failure probability. The model can provide necessary equipment reliability information for proactive risk management at the lease level by providing quantitative information to base allocation of maintenance resources to high-risk equipment that will minimize both lost production and ecosystem damage.     

Survival Trees: An Alternative Non-Parametric Multivariate Technique for Life History Analysis

In this paper an extension of tree-structured methodology to cover censored survival analysis is discussed. Tree-based methods (also called recursive partitioning) provide a useful alternative to the classical survival data analysis techniques, such as the semi-parametric model of Cox, whenever the main purpose is defining groups of individuals, either with complete or censored life history, having different survival probability, based on the values of selected covariates. The essential feature of recursive partitioning is the construction of a decision rule in the form of a binary tree. Trees generally require fewer assumptions than classical methods and handle non standard and non linear data structures efficiently. Tree-growing methods make the processes of covariate selection and grouping of categories in event history models explicit. An example concerning the analysis of time to marriage of Italian women is presented.     

Collaborations with faith‐based social service coalitions

Based on the first national survey of faith‐based social service coalitions in the United States, this article presents data on the degree to which these nonprofit organizations collaborate with other specific organizational types, as well as the range and intensity of these collaborations. In general, faith‐based coalitions tend to collaborate most frequently with other faith‐based agencies, a pattern especially characteristic of the more religiously expressive ones. However, collaboration with non‐faith‐based organizations is also quite common. Based on seven organizational characteristics, we are able to predict which faith‐based coalitions are most likely to collaborate with different types of organizations: coalitions that have more explicitly religious policies and practices with reference to clients and staffs are less likely to participate in intense collaborations with some types of secular organizations, and consistently less likely to do so with all types of governmental agencies.     

Managing the introduction of new technology

Most of the existing literature on the implications of new technology focuses on either its ‘impact’ or the social choices that lie behind strategies for its introduction into work organisations. The problems of managing the implementation of new technology have yet to be extensively examined despite this being one of the most critical aspects in the process of technological change. The findings from two case studies are presented which show how managers in the organisations concerned developed contrasting approaches to the problem of implementation in the context of opportunities and constraints presented by product markets and technological advance. Similarities between the two approaches are identified, in particular the role played by top management support in facilitating the acceptance of the new technology. The argument that management is able to develop a single unitary strategy towards the introduction of new technology is rejected in favour of a view of managerial actions as a series of flexible and changing sub-strategies associated with different stages in the process of change.     

Testing for space-time clusters of unknown size

The Knox test is widely used in epidemiology to test for infection or contagion, which is indicated by an excess of cases that are close both in space and time. Often, however, the values of the space and time critical parameters that define 'closeness' are unknown. An exact test is proposed for this situation, its computer implementation is described and examples of its use on published data sets are given. Other possible applications of the method adopted here are discussed. This is an example of a test where nuisance parameters are absent under H0, and where the distribution of the test statistic can be found numerically.