Modelling a disease-relevant contact network of people who inject drugs

This study uses social network analysis to model a contact network of people who inject drugs (PWID) relevant for investigating the spread of an infectious disease (hepatitis C). Using snowball sample data, parameters for an exponential random graph model (ERGM) including social circuit dependence and four attributes (location, age, injecting frequency, gender) are estimated using a conditional estimation approach that respects the structure of snowball sample designs. Those network parameter estimates are then used to create a novel, model-dependent estimate of network size. Simulated PWID contact networks are created and compared with Bernoulli graphs. Location, age and injecting frequency are shown to be statistically significant attribute parameters in the ERGM. Simulated ERGM networks are shown to fit the collected data very well across a number of metrics. In comparison with Bernoulli graphs, simulated networks are shown to have longer paths and more clustering. Results from this study make possible simulation of realistic networks for investigating treatment and intervention strategies for reducing hepatitis C prevalence.     

Wage Bargaining and Profitability: A Disaggregative Analysis

Abstract. Previous analyses of the wage/profit relationship at a disaggregative level in Britain have given positive results for pre-war years but negative results for early post-war years. However, this is probably due to the increasingly unreliable nature of the enterprise- based profits series published in the National Accounts until 1982. We have constructed, instead, what are essentially establishment-based Census data on profits for fourteen manufacturing industries, up to 1986. We have also been able to extend the disaggregative unemployment data, the publication of which also ceased in 1982. The wage equations that we have estimated include profits and unemployment (and other variables) in an explicit Nash bargaining model, in line with widely held views as to the way that wage negotiations are actually conducted. The results obtained show a highly significant role for profits, as well as having other implications, notably the positive (hysteresis) effect of industry unemployment, by contrast with the normal negative effect of aggregate unemployment, and the important effects of relative wages - which play a large role in various disaggregative studies of the propagation of inflation.     

Who Shall Decide? The Relevance of Theory and Research to Decision-making by People with an Intellectual Disability

In the context of normalisation and rights recognition, capacity for decision-making by people with an intellectual disability has emerged as an important but potentially contentious issue. Although increased community integration has opened up many new options, opportunities for greater autonomy are still unnecessarily constrained. Perceptions of limited competence, the issue of who has control over choices, and organisational structures are some of the factors which influence the extent to which clients are able to make decisions. This paper argues that, in order to resolve these issues, decision-making by people with an intellectual disability should be studied within the broader context of psychological theories of decision-making and human behaviour. Theoretical findings are reviewed and areas identified in which decision-making behaviour may break down. The relevance of theoretical research to issues of competence and empowerment, and to the small body of research on decision-making and choice by people with an intellectual disability is discussed. It is concluded that future research should focus on contextual variables, including the nature of the decision to be made, which affect decision-making competence in people with an intellectual disability.     

Prior distribution elicitation for generalized linear and piecewise-linear models

An elicitation method is proposed for quantifying subjective opinion about the regression coefficients of a generalized linear model. Opinion between a continuous predictor variable and the dependent variable is modelled by a piecewise-linear function, giving a flexible model that can represent a wide variety of opinion. To quantify his or her opinions, the expert uses an interactive computer program, performing assessment tasks that involve drawing graphs and bar-charts to specify medians and other quantiles. Opinion about the regression coefficients is represented by a multivariate normal distribution whose parameters are determined from the assessments. It is practical to use the procedure with models containing a large number of parameters. This is illustrated through practical examples and the benefit from using prior knowledge is examined through cross-validation.