Coherent decision analysis with inseparable probabilities and utilities

This article explores the extent to which a decision maker's probabilities can be measured separately from his/her utilities by observing his/her acceptance of small monetary gambles. Only a partial separation is achieved: the acceptable gambles are partitioned into a set of belief gambles, which reveals probabilities distorted by marginal utilities for money, and a set of preference gambles, which reveals utilities reciprocally distorted by marginal utilities for money. However, the information in these gambles still enables us to solve the decision maker's problem: his/her utility-maximizing decision is the one that avoids arbitrage (i.e., incoherence or Dutch books).     

The ascendancy of primary care: permanent or temporary?

The conventional wisdom strongly suggests a health care provider food chain for the future: Primary care physicians (PCPs), principally family practitioners, on the top playing the lead role, distantly followed by specialists, with hospitals and other ancillary services even further down the line. Is this a reasonable expectation? Will PCPs dominate the new systems? Or will they be but one of many equally necessary components of these developing integrated health care delivery organizations? Looking at the various models now developing, it would seem that future integrated delivery systems will utilize both PCPs and specialists, but with strong augmentation from a diverse assortment of other health care professionals, including nonphysician providers, educators, and administrators. To separate the illusion of primary care dominance of the coming health care system from the likely reality, we should first determine what is driving the apparent present demand for primary care physicians. Next, we will examine the possible and probable reactions to that demand from an economic standpoint and from the points of view of both health care professionals and the public. Finally, we must try to picture how health care provider organizations of the future are likely to look and how they will integrate their health care professionals.     

Mirror, mirror on the wall: reflections from failure to establish a truly uniform national health care policy

When the author gazed into the proverbial mirror and asked if the U.S. health care system was the fairest of them all, it shattered. In this article, Thompson tells why the system is broken and what failure to fix it means to physician executives. He suggests that we, as Americans, must reinvent ourselves by realigning our value systems and and stifling our obsession with profit before trying to reinvent health care.     

Drawing households and other living spaces in the process of assessment and psychotherapy

This paper introduces a drawing technique developed by the author for use in the assessment and treatment of individuals and families. The client is invited to draw a floor plan of his or her home or apartment, or an aerial view of un outdoor area. The drawing is then discussed and considered as a means of understanding critical elements of the experience of life space. The material derived is discussed from the eerspectives of family systems, psychodynamic, and abuse treatment theories, with special reference to notions of family structure, boundary, the self, and memory. Emphasis is placed on the actual physical layout of the home, as well as the subjective experience of it. Applications of the drawing technique for exploring memories are illustrated. Case examples are presented from clinical trials with children and adults in residential treatment, inpatient, and outpatient settings.The Heller Financial Corporation generously supports the development of household and spatial drawings for treatment and prevention. A version of this paper was presented at the 43rd Annual Meeting of the American Association of Psychiatric Services for Children, New Orleans, February 26, 1992. The author wishes to thank Robert B. Bloom, Ph.D., Excutive Director of JCB, for supporting the development of ideas and techniques discribed in this paper.     

Nondictatorially independent pairs

Suppose that social welfare function f satisfies the Pareto condition and has complete and transitive values. On a domain satisfying the free quadruple property, if the outcome set X has m< outcomes, then the set of pairs of distinct alternatives on which f satisfies both independence and nondictatorship contains at most the fraction 2/m of all pairs. On a domain satisfying the free six-tuple property, if X is a subset of Euclidean space then the set of pairs on which f satisfies both independence and nondictatorship has Lebesgue measure zero.Campbell's research was financed by the National Science Foundation, grant SES 9209039.     

An analytic method for randomized trials with informative censoring: Part 1

Consider a randomized trial in which time to the occurrence of a particular disease, say pneumocystis pneumonia in an AIDS trial or breast cancer in a mammographic screening trial, is the failure time of primary interest. Suppose that time to disease is subject to informative censoring by the minimum of time to death, loss to and end of follow-up. In such a trial, the censoring time is observed for all study subjects, including failures. In the presence of informative censoring, it is not possible to consistently estimate the effect of treatment on time to disease without imposing additional non-identifiable assumptions. The goals of this paper are to specify two non-identifiable assumptions that allow one to test for and estimate an effect of treatment on time to disease in the presence of informative censoring. In a companion paper (Robins, 1995), we provide consistent and reasonably efficient semiparametric estimators for the treatment effect under these assumptions. In this paper we largely restrict attention to testing. We propose tests that, like standard weighted-log-rank tests, are asymptotically distribution-free -level tests under the null hypothesis of no causal effect of treatment on time to disease whenever the censoring and failure distributions are conditionally independent given treatment arm. However, our tests remain asymptotically distribution-free -level tests in the presence of informative censoring provided either of our assumptions are true. In contrast, a weighted log-rank test will be an -level test in the presence of informative censoring only if (1) one of our two non-identifiable assumptions hold, and (2) the distribution of time to censoring is the same in the two treatment arms. We also extend our methods to studies of the effect of a treatment on the evolution over time of the mean of a repeated measures outcome, such as CD-4 count.     

"SECRET BALLOTS" AND SELF-REPORTS IN AN EXIT-POLL EXPERIMENT

A controlled exit-poll experiment on Election Day (November3, 1992) shows that refusals to answer questions and other evasiveforms of responding were significantly lower when respondentswere given a self-administered "secret-ballot" questionnairethan when they were interviewed face-to-face. While there weresome suggestive interactions of this mode-of-data collectioneffect with age and sex, and with the partisan atmosphere ofthe precinct in which the interviews were conducted, they wereborderline in significance, inconsistent in pattern, or difficuitto interpret. More important, comparisons with official electionreturns (the truth) indicated that the secret-ballot techniquewas more accurate than were face-to-face interviews in estimatingthe final outcome on the most socially sensitive of three self-reportedvotes: a vote for or against a tax levy for elderly services.Using a genuine secret ballot in the tradition of the olderGallup preelection polls can thus increase the validity of self-reportsin exit polls today.     

Implementing partial least squares

Partial least squares (PLS) regression has been proposed as an alternative regression technique to more traditional approaches such as principal components regression and ridge regression. A number of algorithms have appeared in the literature which have been shown to be equivalent. Someone wishing to implement PLS regression in a programming language or within a statistical package must choose which algorithm to use. We investigate the implementation of univariate PLS algorithms within FORTRAN and the Matlab (1993) and Splus (1992) environments, comparing theoretical measures of execution speed based on flop counts with their observed execution times. We also comment on the ease with which the algorithms may be implemented in the different environments. Finally, we investigate the merits of using the orthogonal invariance of PLS regression to improve the algorithms.     

A simple,automatic and adaptive bivariate density estimator based on conditional densities

The standard approach to non-parametric bivariate density estimation is to use a kernel density estimator. Practical performance of this estimator is hindered by the fact that the estimator is not adaptive (in the sense that the level of smoothing is not sensitive to local properties of the density). In this paper a simple, automatic and adaptive bivariate density estimator is proposed based on the estimation of marginal and conditional densities. Asymptotic properties of the estimator are examined, and guidance to practical application of the method is given. Application to two examples illustrates the usefulness of the estimator as an exploratory tool, particularly in situations where the local behaviour of the density varies widely. The proposed estimator is also appropriate for use as a pilot estimate for an adaptive kernel estimate, since it is relatively inexpensive to calculate.