Estimation of location extremes within general families of scale mixtures

In this paper, we study the estimation of the minimum and maximum location parameters, respectively, representing the minimum guaranteed lifetime of series and parallel systems of components, within a general class of scale mixtures. The conditional or underlying distribution has only the primary restriction of being a location-scale family with positive support. The mixing distribution is also quite general in that we only assume that it has positive support and finite second moment. For demonstrative purposes several special cases are highlighted such as the gamma, inverse-Gaussian, and discrete mixture. Various estimators, including bootstrap bias corrected estimators, are compared with respect to both mean-squared-error and Pitman's measure of closeness.     

Bayesian modelling of catch in a north-west Atlantic fishery

Summary. We model daily catches of fishing boats in the Grand Bank fishing grounds. We use data on catches per species for a number of vessels collected by the European Union in the context of the Northwest Atlantic Fisheries Organization. Many variables can be thought to influence the amount caught: a number of ship characteristics (such as the size of the ship, the fishing technique used and the mesh size of the nets) are obvious candidates, but one can also consider the season or the actual location of the catch. Our database leads to 28 possible regressors (arising from six continuous variables and four categorical variables, whose 22 levels are treated separately), resulting in a set of 177 million possible linear regression models for the log-catch. Zero observations are modelled separately through a probit model. Inference is based on Bayesian model averaging, using a Markov chain Monte Carlo approach. Particular attention is paid to the prediction of catches for single and aggregated ships.     

Does parents’ valuation of children’s health mimic their valuation of own health?

A single latent variable model of health status and therapeutic health care utilization is estimated for parents and own children of 6,557 US households. The equation system that identifies latent health status simultaneously determines a number of indicators of general health, including presence of morbidity symptoms, mobility limitations, medication needs, and utilization of therapeutic health care services. The main goal of the paper was to obtain an unbiased estimate of parents’ marginal substitution rate between own and child health. Results indicate that parents’ valuation of their children’s health exceeds their valuation of own health by almost twofold on average.

Quantifying uncertainty in the biospheric carbon flux for England and Wales

Summary.  A crucial issue in the current global warming debate is the effect of vegetation and soils on carbon dioxide (CO₂) concentrations in the atmosphere. Vegetation can extract CO₂ through photosynthesis, but respiration, decay of soil organic matter and disturbance effects such as fire return it to the atmosphere. The balance of these processes is the net carbon flux. To estimate the biospheric carbon flux for England and Wales, we address the statistical problem of inference for the sum of multiple outputs from a complex deterministic computer code whose input parameters are uncertain. The code is a process model which simulates the carbon dynamics of vegetation and soils, including the amount of carbon that is stored as a result of photosynthesis and the amount that is returned to the atmosphere through respiration. The aggregation of outputs corresponding to multiple sites and types of vegetation in a region gives an estimate of the total carbon flux for that region over a period of time. Expert prior opinions are elicited for marginal uncertainty about the relevant input parameters and for correlations of inputs between sites. A Gaussian process model is used to build emulators of the multiple code outputs and Bayesian uncertainty analysis is then used to propagate uncertainty in the input parameters through to uncertainty on the aggregated output. Numerical results are presented for England and Wales in the year 2000. It is estimated that vegetation and soils in England and Wales constituted a net sink of 7.55 Mt C (1 Mt C = 10¹² g of carbon) in 2000, with standard deviation 0.56 Mt C resulting from the sources of uncertainty that are considered.     

Commonality and Difference in the Movement: an 'Association of Blind Asians' in Leeds

Qualitative research with a group of blind Asian people in Leeds indicated that issues of 'difference' were perceived as more important in mobilising disabled people at a local level than the issues of 'commonality' which characterise the international disability movement. Respondents identified more strongly with their experience of specific impairment and specific cultural identity than with their common experience of disablement. It is argued that such issues are common to other social movements and that the disability movement can learn much from the histories of Black people's movements and the women's movement. In building a successful movement at a local, national and international level, disability alliances will need to challenge racist stereotypes about Black disabled people and their families. They will need to support Black-led groups which organise separately while, at the same time, creating more enabling environments for Black people to participate more fully.     

Police Reforms in Child Abuse Investigation: Their Success and Limitations in the Struggle to Uphold Children's Rights

SUMMARY. The past decade has shown increased awareness, concern and understanding about the extent of child abuse, particularly sexual abuse, and the caring agencies response to listen to and to support the young victims. This article looks at the response of the police service over that decade to meet such demands and to work jointly and responsively with social services to further the welfare and protection of children. It also examines the constraints and limitations of the police and social services when they attempt to uphold the rights of child victims and to gain redress through the criminal justice system     

The repeated public goods game: A solution using Tit-for-Tat and the Lindahl point

This paper demonstrates how a repeated public goods problem may be solved by using Tit-for-Tat (TFT) on the Lindahl point. The general solution is developed; geometric and numerical examples are offered.I wish to thank an anonymous reviewer for very helpful comments on earlier drafts of this paper.