Bayesian analysis of mixture modelling using the multivariate t distribution

A finite mixture model using the multivariate t distribution has been shown as a robust extension of normal mixtures. In this paper, we present a Bayesian approach for inference about parameters of t-mixture models. The specifications of prior distributions are weakly informative to avoid causing nonintegrable posterior distributions. We present two efficient EM-type algorithms for computing the joint posterior mode with the observed data and an incomplete future vector as the sample. Markov chain Monte Carlo sampling schemes are also developed to obtain the target posterior distribution of parameters. The advantages of Bayesian approach over the maximum likelihood method are demonstrated via a set of real data.     

Trade-Offs Between Formal Home Health Care and Informal Family CareGiving

Using 1994 National Long Term Care Survey data, we estimated logistic regressions of formal and informal home health care use and hours. Home health care use and intensity were differentially impacted by chronic conditions, are higher for Medicaid enrollees and rural or small town residents, but lower for HMO enrollees. Decreases in the probability of home health care use increased informal instrumental activities of daily living (IADL) support four hours and decreased informal activities of daily living (ADL) support eight hours weekly. IADL caregiving substituted for formal care, but ADL caregiving declined with reductions in formal care. Public policy reducing formal home health care access may reduce informal ADL caregiving and increase informal IADL caregiving, producing net declines in support.     

Decision analysis for practical negotiation application

The family of decision analysis techniques can be applied effectively to support practical negotiators in international settings. These techniques are most appropriate in support of the prenegotiation phase, when parties are diagnosing the situation, assessing their own plans and strategies, and evaluating likely reactions and outcomes. The paper identifies how these approaches have and can be used to assist negotiation practitioners, offers a rationale for the application of decision analytic approaches in terms of the particular analytical requirements of the prenegotiation period, suggests how these process-oriented tools can be integrated with substantive tools, and discusses ways in which these tools can be presented and delivered to practitioners in a practical and confidence-building manner.     

Student perceptions of the danger of drug use: a factor analysis.

Australian secondary school students from three Year levels were asked to rate the danger involved in various uses of alcohol, tobacco, inhalants, marijuana and other illicit drugs. These ratings were then factor analyzed for each Year level. The results showed a more refined discrimination among the older students, with type of drug and frequency of use being important considerations. Familiarity was a major consideration for the younger students. The cognitive factors derived from the data are consistent with expectations based on the gateway theory of drug use.     

Stress at work and psychological and immunological parameters in a group of Norwegian female bank employees

This study concerned the immunological correlates of stress and work. Self reported stress, emotional state, ego-strength, and defensiveness were examined in relation to measures of cellular immunity (T-cell response to Con A and number of T4 and T8 cells) and humoral immunity (concentrations of immunoglobulins and complement components in plasma) in a group of 96 Norwegian female bank employees. The analyses showed that workload, the stress factor with the highest group mean, was associated with number of T-cells, while strain due to body posture during work was related to concentrations of IgM and C3. Further, depression was significantly correlated with IgM concentration and T-cell number, and anxiety with C3 concentration. T-cell activity was the immunological parameter most consistently associated with psychological well-being, showing positive correlations with defensiveness and ego-strength and negative correlations with anxiety and depression. In conclusion, T-cell number and concentrations of IgM and C3 were sensitive to both work-related stress experience and emotional distress. Coping abilities, indicated by the MMPI Ego-strength scale and emotional distress, were reflected in T-cell activity; insufficient coping was associated with low T-cell activity.