Circuit optimization via sequential computer experiments: design of an output buffer

In electrical engineering, circuit designs are now often optimized via circuit simulation computer models. Typically, many response variables characterize the circuit's performance. Each response is a function of many input variables, including factors that can be set in the engineering design and noise factors representing manufacturing conditions. We describe a modelling approach which is appropriate for the simulator's deterministic input–output relationships. Non-linearities and interactions are identified without explicit assumptions about the functional form. These models lead to predictors to guide the reduction of the ranges of the designable factors in a sequence of experiments. Ultimately, the predictors are used to optimize the engineering design. We also show how a visualization of the fitted relationships facilitates an understanding of the engineering trade-offs between responses. The example used to demonstrate these methods, the design of a buffer circuit, has multiple targets for the responses, representing different trade-offs between the key performance measures.     

Curved Chaotic Map Time Series Models and Their Stochastic Reversals

This paper considers two types of chaotic map time series models, including the well-known tent, logistic and binary-shift maps as special cases; these are called curved tent and curved binary families. Deterministic behaviour is investigated by invariant distributions, Lyapunov exponents, and by serial dependency. Stochastic time reversal of the families is shown to produce models which have a broader range of stochastic and chaotic properties than their deterministic counterparts. The marginal distributions may have concentrations and restricted supports and are shown to be a non-standard class of invariant distribution. Dependenc y is generally weaker with the reversed stochastic models. The work gives a broad statistical account of deterministic and stochastically reversed map models, such as are emerging in random number generation, communica tion systems and cryptography     

The paradox of multiple elections

Assume that voters must choose between voting yes (Y) and voting no (N) on three propositions on a referendum. If the winning combination is NYY on the first, second, and third propositions, respectively, the paradox of multiple elections is that NYY can receive the fewest votes of the 2³ = 8 combinations. Several variants of this paradox are illustrated, and necessary and sufficient conditions for its occurrence, related to the “incoherence” of support, are given. The paradox is shown, via an isomorphism, to be a generalization of the well-known paradox of voting. One real-life example of the paradox involving voting on propositions in California, in which not a single voter voted on the winning side of all the propositions, is given. Several empirical examples of variants of the paradox that manifested themselves in federal elections – one of which led to divided government – and legislative votes in the US House of Representatives, are also analyzed. Possible normative implications of the paradox, such as allowing voters to vote directly for combinations using approval voting or the Borda count, are discussed. Received: 31 July 1996 / Accepted: 1 October 1996     

Organizational effectiveness. Primary care and the congruence model

The congruence model is a framework used to analyze organizational strengths and weaknesses and pinpoint specific areas for improving effectiveness. This article provides an overview of organizations as open systems, with examples in the primary care arena. It explains and applies the congruence model in the context of primary care issues and functions, including methods by which the model can be used to diagnose organizational problems and generate solutions. Changes needed in primary care due to the managed care environment, and areas of potential problems and sensitivities requiring organizational changes to meet market and regulatory demands now placed on PCOs are examined.     

The medical practice as business organization

Medical practices historically have not been examined in terms of their organizational structures and of the appropriateness of their structures for survival as business entities. In this paper, we propose a model for the typical medical practice and discuss its fit with current organizational theory. It is apparent that the medical practice organization does not fit with the demands of a rapidly changing and complex environment. To survive and grow, the medical practice organization must align itself with others that have an interest and stake in the health care system, develop teamwork among physicians, bridge the gap between physicians and others in the organization, and recognize that the work done in the organization depends on other components of the organization.     

Suggestions for management training of residents

In addition to having medical expertise, physicians must possess managerial skills to deal with the ever-changing business environment of the practice of medicine. This article addresses the need for management training of physicians and calls for management training during residency and medical school. It also describes one residency program's efforts to provide comprehensive management training to its residents in pathology.     

Physician career development: toward building a model

Virtually no managed care organization provides a comprehensive and integrated program for physician career development. That's the principal finding of a survey we carried out in Spring 1994 in which we interviewed several individuals who have proven instrumental in the creation of career development programs at their managed care organizations. We started our research with the hypothesis that career development programs for physicians--frequently the most highly paid category of employees and the ones often most directly involved in the delivery of health care--should parallel the mission of the organization. In many of the organizations we surveyed, the mission included clinical excellence, managerial competence, research, teaching, community service, and building shareholder equity. While each organization offered some component of career development--usually clinical improvement and management development--very few offered programs that fostered the continued professional development of physicians in other aspects of their missions. In most cases, even in organizations with stronger career development agendas, the programs were passive and were rarely linked to the overall "corporate" goal of the managed care institution. This critical disconnect makes it extremely difficult for health care organizations to develop a workable system of accountability for their career development programs.     

Physician glut. Physicians--the next victims of "downsizing?"

Should physicians really be polishing up their CVs or preparing to enter another line of work? In a word: No. What a recent survey makes clear is that, while managed care is driving physicians from some markets, jobs are still available in other markets traditionally underserved by physicians. This is not to suggest that the physician employment market has gone unchanged. Many physicians, particularly specialists, have taken income hits, and some specialists truly are in need of work. Primary care physicians, however, have seen their stars rise and are now in a position to work wherever they want. Physicians may no longer be able to practice within 50 miles of where they were raised or where they were trained, as has been their wont. Instead, they will have to do what other professionals have long done--go where job opportunities take them. In short, they will have to add a career strategy to their scientific mindset, and that means an aggressive job search, coupled with a strong consumer orientation.