A hierarchical eigenmodel for pooled covariance estimation

Summary.  Although the covariance matrices corresponding to different populations are unlikely to be exactly equal they can still exhibit a high degree of similarity. For example, some pairs of variables may be positively correlated across most groups, whereas the correlation between other pairs may be consistently negative. In such cases much of the similarity across covariance matrices can be described by similarities in their principal axes, which are the axes that are defined by the eigenvectors of the covariance matrices. Estimating the degree of across-population eigenvector heterogeneity can be helpful for a variety of estimation tasks. For example, eigenvector matrices can be pooled to form a central set of principal axes and, to the extent that the axes are similar, covariance estimates for populations having small sample sizes can be stabilized by shrinking their principal axes towards the across-population centre. To this end, the paper develops a hierarchical model and estimation procedure for pooling principal axes across several populations. The model for the across-group heterogeneity is based on a matrix-valued antipodally symmetric Bingham distribution that can flexibly describe notions of 'centre' and 'spread' for a population of orthogonal matrices.     

The new breed

Structural changes within the health system--particularly in the organization and financing of services--have made new and different opportunities available to physicians interested in management. What types of physicians are currently going into management? How do they compare to others who have been in management for a longer period of time and to the "traditional" portrait of the physician executive? The author profiles the emerging, contemporary physician executive and explores the implications for the viability of the field of medical management as a whole.     

Thriving and surviving in a new medical career: the case of hospitalist physicians

Managed care is cultivating a variety of new work careers within the medical profession, and it is worth asking whether they will function as long- or shorter-term career options for the individuals who participate in them. This paper uses the specific case of hospitalist physicians to explore how the surrounding social and economic work contexts contribute to two individual-level outcomes that inform the issue of career longevity: the concepts of burnout and intent to stay in the career. The findings of a national survey of hospitalists reveal that job burnout and intent to remain in the career are more meaningfully associated with favorable social relations involving colleagues, co-workers, and patients than with negative experiences related to the economically induced pressures of the job, such as reduced autonomy and the use of financial incentives. In addition, career longevity is enhanced by the extent to which individual physicians pursue intrinsic and extrinsic rewards through their choices to become hospitalists. These findings demonstrate that sociologists should pay greater attention to the career trajectories of contemporary doctors in order to understand larger scale professional stratification within medicine. They also offer empirical support for redirecting our focus towards the relational dynamics that shape these trajectories.     

Bridging gaps between mind, body, & spirit. Healing the whole person.

Fifty percent of visits of primary care providers are for psychiatric problems making it desirable to screen for mental, addictive, or behavioral disorders at the level of primary care. Psychiatric/mental health nurses prepared at the master's level to practice in the blended clinical specialist/nurse practitioner role are well placed to treat or collaborate in the treatment of people who present with symptoms of physical or psychological problems. The role of the clinical specialist/nurse practitioner is evolving in response to changes in health demographics, epidemiology, scientific and technological advances, and changes in managed care. Advanced practice nursing education must continue to anticipate and meet on-going changes and challenges.