A Comparison of Bayesian and Sampling Theory Inferences in a Probit Model

HE PROBIT MODEL IS A POPULAR DEVICE for explaining binary choice decisions in econometrics. It has been used to describe choices such as labor force participation, travel mode, home ownership, and type of education. These and many more examples can be found in papers by Amemiya (1981) and Maddala (1983). Given the contribution of economics towards explaining such choices, and given the nature of data that are collected, prior information on the relationship between a choice probability and several explanatory variables frequently exists. Bayesian inference is a convenient vehicle for including such prior information. Given the increasing popularity of Bayesian inference it is useful to ask whether inferences from a probit model are sensitive to a choice between Bayesian and sampling theory techniques. Of interest is the sensitivity of inference on coefficients, probabilities, and elasticities. We consider these issues in a model designed to explain choice between fixed and variable interest rate mortgages. Two Bayesian priors are employed: a uniform prior on the coefficients, designed to be noninformative for the coefficients, and an inequality restricted prior on the signs of the coefficients. We often know, a priori, whether increasing the value of a particular explanatory variable will have a positive or negative effect on a choice probability. This knowledge can be captured by using a prior probability density function (pdf) that is truncated to be positive or negative. Thus, three sets of results are compared:those from maximum likelihood (ML) estimation, those from Bayesian estimation with an unrestricted uniform prior on the coefficients, and those from Bayesian estimation with a uniform prior truncated to accommodate inequality restrictions on the coefficients.

Public choice of species for the ark: Phylogenetic similarity and preferred wildlife species for survival

Humans play a role in deciding the fate of species in the current extinction wave. Because of the previous Similarity Principle, physical attractiveness and likeability, it has been argued that public choice favours the survival of species that satisfy these criteria at the expense of other species. This paper empirically tests this argument by considering a hypothetical ‘Ark’ situation. Surveys of 204 members of the Australian public inquired whether they are in favour of the survival of each of 24 native mammal, bird and reptile species (prior to and after information provision about each species). The species were ranked by percentage of ‘yes’ votes received. Species composition by taxon in various fractions of the ranking was determined. If the previous Similarity Principle holds, mammals should rank highly and dominate the top fractions of animals saved in the hierarchical list. We find that although mammals would be over-represented in the ‘Ark’, birds and reptiles are unlikely to be excluded when social choice is based on numbers ‘voting’ for the survival of each species. Support for the previous Similarity Principle is apparent particularly after information provision. Public policy implications of this are noted and recommendations are given.

Early life course determinants of young adults' gambling behaviour. An Australian Longitudinal Study

Problem gambling represents a public concern as both a social and health issue. Available evidence shows problem gambling is associated with a range of psychological disorders, criminality, and disruption to families. While gambling itself may represent a pleasurable pursuit for the majority, for a proportion, gambling-related activities may assume many of the characteristics of an addiction and have the capacity to undermine individuals� mental and physical health, social relationships, financial independence, as well as the financial and psychological wellbeing of their families and/or friends. The objectives of this study are based on the need to increase our understanding of gambling behaviour, its antecedents, as well its influence on the health and wellbeing of gamblers and their families. One of the most important and unresolved issues in gambling research is whether the mental health and social/family correlates of gambling precede or follow gambling behaviour. This report focuses on this issue.

Closure of the Challinor Centre II: An extended report on 95 individuals after 12 months of community living

As part of an institutional closure programme, 95 individuals with an intellectual disability were relocated to community-based group homes. Each individual was assessed 6 months prior to the relocation and then again after 1, 6, and 12 months of community living. Assessments involved ratings of adaptive and maladaptive behaviour, choice-making, and life circumstances. The group means comparing institution to community ratings showed improvements in adaptive functioning but no significant change in maladaptive behaviour. There were also improvements in life circumstances and increased opportunities for choice-making following relocation to the community. These outcomes suggest that relocation to the community was associated with a more active and normalised lifestyle than experienced in the institutional setting.

Prevalence of Adverse Life Events, Depression and Suicidal Thoughts and Behaviour among a Community Sample of Young People aged 15-24 Years

Objective: To provide prevalence data on several key mental health indicators for young people aged 15 to 24 years. Methods: A cross-sectional household survey, using telephone recruitment followed by a postal pencil-and-paper questionnaire. The overall response rate was 67.3%. Results: Difficulties with interpersonal relationships are common causes of distress for young people, in particular problems with parents, problems with friends and relationship break-ups. Depressive symptomatology is common among young people with approximately one in eight males and one in four females reporting current depressive symptomatology. One in three young people reported that they had had suicidal thoughts at some time in the past, 1.2% of young people reported that they had made a plan on how to kill themselves in the four-week period prior to completing the survey and 6.9% of young people reported that they had tried to kill themselves at some time during their life time (4.2% of males and 9.0% of females). Conclusions and implications: The prevalence figures for the various mental health indicators presented in this paper represent good baseline information upon which to examine the progress over time of interventions designed to improve the mental health of young people.

The behaviour of phenylphosphine oxide containing polyimides in a water plasma following gamma-radiolysis

The surface oxidation of two polyimides containing fluorinated phenylphosphine oxide units, TOR-RC and TOR-RC ODPA, have been studied by (XPS) spectroscopy following gamma -radiolysis under vacuum or in air and subsequent treatment in a water plasma. The changes in the O 1s/C 1s ratios obtained from (XPS) analysis showed that on exposure to the water plasma the ratio increases and then levels to a constant value which is similar to that found for exposure to the plasma without prior gamma -radiation treatment. Evidence for the formation of phosphate species was also obtained from the (XPS) analyses. (C) 2001 Elsevier Science Ltd. All rights reserved.