Clustering objects on subsets of attributes (with discussion)

Summary.  A new procedure is proposed for clustering attribute value data. When used in conjunction with conventional distance-based clustering algorithms this procedure encourages those algorithms to detect automatically subgroups of objects that preferentially cluster on subsets of the attribute variables rather than on all of them simultaneously. The relevant attribute subsets for each individual cluster can be different and partially (or completely) overlap with those of other clusters. Enhancements for increasing sensitivity for detecting especially low cardinality groups clustering on a small subset of variables are discussed. Applications in different domains, including gene expression arrays, are presented.     

EFFECTS OF SOLUTION FOCUSED THERAPY'S "FORMULA FIRST SESSION TASK" ON COMPLIANCE AND OUTCOME IN FAMILY THERAPY

This study investigated the immediate impact of a "solution focused" family therapy intervention on both the family and the therapist. Specifically, the study examined the differential effects of the formula first session task (FFST) recommended by de Shazer (1982, 1985), as well as the FFST plus solution focused therapy, as compared to a standard problem focused structural-strategic intervention. After one week, the groups receiving the FFST were significantly higher on measures of family compliance, clarity of treatment goals, and improvement in the presenting problem. However, there were no significant differences among groups on family optimism or on outcome after 10 sessions. The implications of these results are discussed.     

The Dilemmas of Regulating Casino Gambling

One of the major reasons for the reluctance to legalize many of the popular forms of gambling is the belief that these forms are particularly difficult to control honestly. It is generally believed that organized crime has been able to undermine regulatory mechanisms. This paper reports on the difficulties and successes of the Nevada Gambling Control Board's efforts to deal with a sophisticated and complex form of gambling organization and compares and contrasts that regulation with the regulation of casino gambling in England.     

Design and analysis of computer experiments when the output is highly correlated over the input space

To build a predictor, the output of a deterministic computer model or “code” is often treated as a realization of a stochastic process indexed by the code's input variables. The authors consider an asymptotic form of the Gaussian correlation function for the stochastic process where the correlation tends to unity. They show that the limiting best linear unbiased predictor involves Lagrange interpolating polynomials; linear model terms are implicitly included. The authors then develop optimal designs based on minimizing the limiting integrated mean squared error of prediction. They show through several examples that these designs lead to good prediction accuracy.     

Amateur craft‐artists: Marginal leisure roles in a marginal art world (1)

Amateurism is an important but marginal leisure role, in which the boundaries between work and leisure are blurred. This phenomenon has been studied by Stebbins as a subjective social reality. His conceptualization of amateurism was used as a model in the examination of survey data on craft‐artists and it was found to apply rather well to the analysis of quantitative data. As a self‐identified category of craft‐artists, amateurs were statistically marginal between professionals and dabblers.     

On Semiparametric Mode Regression Estimation

It has been found that, for a variety of probability distributions, there is a surprising linear relation between mode, mean, and median. In this article, the relation between mode, mean, and median regression functions is assumed to follow a simple parametric model. We propose a semiparametric conditional mode (mode regression) estimation for an unknown (unimodal) conditional distribution function in the context of regression model, so that any m-step-ahead mean and median forecasts can then be substituted into the resultant model to deliver m-step-ahead mode prediction. In the semiparametric model, Least Squared Estimator (LSEs) for the model parameters and the simultaneous estimation of the unknown mean and median regression functions by the local linear kernel method are combined to infer about the parametric and nonparametric components of the proposed model. The asymptotic normality of these estimators is derived, and the asymptotic distribution of the parameter estimates is also given and is shown to follow usual parametric rates in spite of the presence of the nonparametric component in the model. These results are applied to obtain a data-based test for the dependence of mode regression over mean and median regression under a regression model.     

On the relative behavior of estimators of reliability/survivability

Based on a decomposition of mean absolute error, a twofold technique is introduced whereby a pairwise comparison of point estimators of reliability/survivability can be made. Given two such estimators, the method examines (a) the “odds” in favor of one of the estimators being closer to the true value than is the other and (b) each estimator’s average closeness to the true value not only when it is closer than is the other but also when it is not. Joint consideration of these concepts is shown to form a basis for determining which of the two estimators is preferred in a given situation. An application of the theory is made by comparing the maximum likelihood and minimum variance unbiased estimators of reliability/survivability in the exponential failure model.     

Incorporating physiology into parasitoid behavioral ecology: the allocation of nutritional resources

A critical problem faced by most theoretical studies of parasitoid behavior and population dynamics has been the paucity of empirically obtained information about the pattern of resource allocation to egg production and metabolic maintenance in relation to adult diet in female parasitoids. This review calls for a shift from traditional manipulative feeding studies to studies that quantify the energetic budget of parasitoids and which take into account the dynamic nature of metabolic processes. As guidelines, we highlight the advances made along these lines with other insect groups and some of the simplest tools already available today for fulfilling this goal. Received: December 22, 1998 / Accepted: January 12, 1999