LOWER BOUNDS FOR THE DIVERGENCE OF DIRECTIONAL AND AXIAL ESTIMATORS

Consider estimation of a unit vector parameter a in two classes of distributions. In the first, α is a direction. In the second, α is an axis, so that –α and α are equivalent: the aim is to obtain the projector αα^t. In each case the paper uses first principles to define measures of the divergence of such estimators and derives lower bounds for them. These bounds are computed explicitly for the Fisher-Von Mises and Scheidegger-Watson densities on the g-dimensional sphere, ω_q. In the latter case, the tightness of the bound is established by simulations.     

Large sample theory of the Langevin distribution

The Langevin (or von Mises-Fisher) distribution of random vector x on the unit sphere ω_q in $\text{R}$^q has a density proportional to exp κμ'x where μ'x is the scalar product of x with the unit modal vector μ and κ?0 is a concentration parameter. This paper studies estimation and tests for a wide variety of situations when the sample sizes are large. Geometrically simple test statistics are given for many sample problems even when the populations may have unequal concentration parameters.     

Gay Men's Knowledge of HIV Transmission and ‘Safe’ Sex: A Question of Accuracy

The study described in this paper is part of a project assessing the impact of the HIV epidemic on 535 men who have sex with men. These men were surveyed about their knowledge of HIV, their sexual practices, other issues concerning the transmission of HIV, and AIDS. This paper focuses on these men's beliefs about HIV transmission, their perceptions of the safety of a number of sexual and social practices, and the factors influencing these perceptions. The findings indicate, in general, that the men surveyed were moderately well informed about HIV transmission. Some twenty percent of the men were well-informed about both ‘safe’ and ‘unsafe’ sexual practices, a small number were ill-informed and the remainder, the majority, were well-informed about some aspects and ill-informed about others. The data suggest that information from the mainstream and gay press is not only differentially available but that information is processed and interpreted by the men in different ways. Variables which influence the manner in which information is interpreted are place of residence (locale), awareness of gay community posters and pamphlets, and the men's sexual practice; these are associated with cautiousness or rashness in the men's judgments of safety and risk.     

Work/Family Policies,The Changing Role of Fathers and The Presumption of Shared Responsibility for Parenting

Recent approaches to work/family policies which emphasise options for women have the potential to reinforce gender divisions of labour and to increase conflicts between paid work and family. It is argued here that more account needs to be taken of the interaction between male and female commitments to work and family, and of the possible increased involvement by men in family life. The movement away from the traditional role as the autocratic head of the household towards a more nurturant and available father role, while still small, appears to be gathering momentum. This is reflected in recent research findings, in newspaper articles and other media reports, and in proposals for changes in employment policies (e.g., the ACTU “family leave” test case). While research and everyday accounts provide some hope for future changes in gender divisions of labour, more caution needs to be taken in interpreting research findings and in making statements about the extent to which change has already occurred. A radical new direction in approaches to policy development is needed if the existing status quo of father as the major breadwinner and more distant family member, and mother as the housewife, nurturer and supplementary income earner, is to be altered. Suggestions are made for the development of policies that would both respond to the needs of fathers who are primary caregivers, and help promote a greater sharing of parenting responsibilities by fathers. The basis of these proposals is an argument for the adoption of a presumption of shared parenting to parallel the current presumption of gender equality in the paid workforce.     

Investigating Unexpected Child Deaths: An Audit of the New Joint Agency Approach

• The joint agency approach should be used to investigate all unexpected child deaths
• Practitioners should ensure that final case discussions are not unduly delayed so that parents do not have to wait several months for information on the cause of their child's death.
• All bereaved parents should be given the opportunity to have a follow‐up appointment with the paediatrician responsible for managing sudden unexpected death in children.

     

Coal demand,market forces,and U.S. coal mine closures

Economic transitions have the potential to displace workers and cause social unrest. Coal mine closures and the resulting employment losses in rural areas have become salient issues. Using data on coal mine and power plant operation, we model closure as a function of expected profits, which allows us to compare the effects on mine closure of specific demand and supply shocks to expected mine profits. Increasing costs of production have had a large impact on closures, but lower natural gas prices and lower electricity demand have played more recently important roles.