RAND Corporation

About: RAND Corporation is a nonprofit organization based out in Santa Monica, California, United States. It is known for research contribution in the topics: Population & Health care. The organization has 9602 authors who have published 18570 publications receiving 744658 citations.

Geometric Properties of the Kernel, Nucleolus, and Related Solution Concepts

Abstract: Two solution concepts for cooperative games in characteristic-function form, the kernel and the nucleolus, are studied in their relationship to a number of other concepts, most notably the core. The unifying technical idea is to analyze the behavior of the strong e-core as e varies. One of the central results is that the portion of the prekernel that falls within the core, or any other strong e-core, depends only on the latter's geometrical shape. The prekernel is closely related to the kernel and often coincides with it, but has a simpler definition and simpler analytic properties. A notion of “quasi-zero-monotonicity” is developed to aid in enlarging the class of games in which kernel considerations can be replaced by prekernel considerations. The nucleolus is approached through a new, geometrical definition, equivalent to Schmeidler's original definition but providing very elementary proofs of existence, unicity, and other properties. Finally, the intuitive interpretations of the two solution concepts are clarified: the kernel as a kind of multi-bilateral bargaining equilibrium without interpersonal utility comparisons, in which each pair of players bisects an interval which is either the battleground over which they can push each other aided by their best allies if they are strong or the no-man's-land that lies between them if they are weak; the nucleolus as the result of an arbitrator's desire to minimize the dissatisfaction of the most dissatisfied coalition.

Psychometric considerations in evaluating health-related quality of life measures.

Abstract: How does one determine if a measure of health-related quality of life (HRQL) is adequate for clinical trials? Psychometric methods are frequently used to answer this question. What is psychometrics all about? In this paper we address these questions, discussing common psychometric evaluation procedures applied to HRQL measures. Specifically, we discuss issues regarding the evaluation of reliability and validity (including responsiveness).

Managing the Risk of Uncertain Threshold Responses: Comparison of Robust, Optimum, and Precautionary Approaches

Abstract: Many commentators have suggested the need for new decision analysis approaches to better manage systems with deeply uncertain, poorly characterized risks Most notably, policy challenges such as abrupt climate change involve potential nonlinear or threshold responses where both the triggering level and subsequent system response are poorly understood This study uses a simple computer simulation model to compare several alternative frameworks for decision making under uncertainty -- optimal expected utility, the precautionary principle, and three different approaches to robust decision making -- for addressing the challenge of adding pollution to a lake without triggering unwanted and potentially irreversible eutrophication The three robust decision approaches -- trading some optimal performance for less sensitivity to assumptions, satisficing over a wide range of futures, and keeping options open -- are found to identify similar strategies as the most robust choice This study also suggests that these robust decision approaches offer a quantitative, decision analytic framework that captures the spirit of the precautionary principle while addressing some of its shortcomings Finally, this study finds that robust strategies may be preferable to optimum strategies when the uncertainty is sufficiently deep and the set of alternative policy options is sufficiently rich

Androgen deprivation therapy increases cardiovascular morbidity in men with prostate cancer.

Abstract: BACKGROUND. The use of androgen deprivation therapy (ADT) in the treatment of men with prostate cancer has risen sharply. Although cardiovascular disease is the most common reason for death among men with prostate cancer who do not die of the disease itself, data regarding the effect of ADT on cardiovascular morbidity and mortality in men with prostate cancer are limited. In the current study, the authors attempted to measure the risk for subsequent cardiovascular morbidity in men with prostate cancer who received ADT. METHODS. A cohort of newly diagnosed men in a population-based registry who were diagnosed between 1992 and 1996 were identified retrospectively. A total of 22,816 subjects were identified after exclusion criteria were applied. Using a multivariate model, the authors calculated the risk of subsequent cardiovascular morbidity in men with prostate cancer who were treated with ADT, as defined using Medicare claims. RESULTS. Newly diagnosed prostate cancer patients who received ADT for at least 1 year were found to have a 20% higher risk of serious cardiovascular morbidity compared with similar men who did not receive ADT. Subjects began incurring this higher risk within 12 months of treatment. However, Hispanic men were found to have a lowered risk for cardiovascular morbidity. CONCLUSIONS. ADT is associated with significantly increased cardiovascular morbidity in men with prostate cancer and may lower overall survival in men with low-risk disease. These data have particular relevance to decisions regarding the use of ADT in men with prostate cancer in settings in which the benefit has not been clearly established. For men with metastatic disease, focused efforts to reduce cardiac risk factors through diet, exercise, or the use of lipid-lowering agents may mitigate some of the risks of ADT. Cancer 2007;110:1493–500. � 2007 American Cancer Society.