Slope Estimation for Bivariate Longitudinal Outcomes Adjusting for Informative Right Censoring Using Discrete Survival Model: Application to the Renal Transplant Cohort

Patients undergoing renal transplantation are prone to graft failure which causes lost of follow-up measures on their blood urea nitrogen and serum creatinine levels. These two outcomes are measured repeatedly over time to assess renal function following transplantation. Loss of follow-up on these bivariate measures results in informative right censoring, a common problem in longitudinal data that should be adjusted for so that valid estimates are obtained. In this study, we propose a bivariate model that jointly models these two longitudinal correlated outcomes and generates population and individual slopes adjusting for informative right censoring using a discrete survival approach. The proposed approach is applied to the clinical dataset of patients who had undergone renal transplantation. A simulation study validates the effectiveness of the approach.     

The Emergency of Climate Change: Why Are We Failing to Take Action?

Latane and Darley developed a five-stage model to understand why people do and do not help other people in emergency situations. We extend their five-stage model to explore why people do and do not take action against climate change. We identify the factors that make climate change difficult to notice and ambiguous as an emergency; we explore barriers to taking responsibility for action; and we discuss the issues of efficacy and costs versus benefits that make action unlikely. The resulting analysis is useful on two levels. For educators and policy makers, the model suggests the most efficacious approaches to galvanizing action among U.S. citizens. For social scientists, the model provides a valuable framework for integrating research from diverse areas of psychology and suggests fruitful avenues for future empirical research.     

The nature,extent and determinants of violence against psychiatric personnel

Violence against psychiatric staff seems to be on the increase. Such abuse can lead to mental health consequences for the staff and a reluctance to be closely involved with patients. Few Swedish investigations have examined violence against mental nurses and psychiatrists, or undertaken comparative studies between them. In this study we examined the extent, nature and determinants (i.e. risk factors) of violence against psychiatric nurses (n = 731) and psychiatrists (n = 320) working in the eight health care districts of Stockholm. These caregivers were assessed cross-sectionally by means of a questionnaire covering various areas (e.g. violence and work environment). The majority of the participants (85%) reported having been exposed to violence during their careers, with 57% being victimized in the past 12 months. Physical violence was common, and factors such as negative attitudes to work and diminished sense of autonomy were associated with an increased vulnerability to violence. Nurses and psychiatrists did not differ in violence variables. In spite of the weaknesses of the design (cross-sectional self-selecting sample), this study corroborates previous findings and identifies personal factors associated with violence that have received little attention in the literature (e.g. lack of respect for the organization of care).     

Models and estimation for systems with recurrent events and usage processes

This paper considers settings where populations of units may experience recurrent events, termed failures for convenience, and where the units are subject to varying levels of usage. We provide joint models for the recurrent events and usage processes, which facilitate analysis of their relationship as well as prediction of failures. Data on usage are often incomplete and we show how to implement maximum likelihood estimation in such cases. Random effects models with linear usage processes and gamma usage processes are considered in some detail. Data on automobile warranty claims are used to illustrate the proposed models and estimation methodology.     

A rank test for constancy of a location oil scale parameter

X nonlinear rank statistic is proposed to test whether a location or scale parameter of a continuous distribution has remained constant over time. The test is based on frequency domain characteristics of the data and uses the periodogram of appropriate rank scores. The test has good power against alternatives involving multiple abrupt up and down changes     

EMERGING TRENDS IN THE PROVISION AND CONSUMPTION OF HEALTH SERVICES

Health services are examined in terms of emerging trends for the new millennium. On the one hand, centralization is increasing as payers tighten control over disbursements through managed care and more restrictive health insurance. On the other hand, health services are decentralizing as patients acquire more information and take more control of some aspects of treatment. Health services markets now also show signs of becoming global in nature, possibly benefiting both bulk purchasers of care and individual consumers. Any tendencies toward increased patient control are likely to be ephemeral, however: In the absence of reforms sparked by yet-to-be-experienced crises, advances in technology, particularly in medical informatics, will likely be used to strengthen the profit positions of insurance providers, not to provide more comprehensive health care services for patients.