Cautionary Remarks on the Use of Clusterwise Regression

Clusterwise linear regression is a multivariate statistical procedure that attempts to cluster objects with the objective of minimizing the sum of the error sums of squares for the within-cluster regression models. In this article, we show that the minimization of this criterion makes no effort to distinguish the error explained by the within-cluster regression models from the error explained by the clustering process. In some cases, most of the variation in the response variable is explained by clustering the objects, with little additional benefit provided by the within-cluster regression models. Accordingly, there is tremendous potential for overfitting with clusterwise regression, which is demonstrated with numerical examples and simulation experiments. To guard against the misuse of clusterwise regression, we recommend a benchmarking procedure that compares the results for the observed empirical data with those obtained across a set of random permutations of the response measures. We also demonstrate the potential for overfitting via an empirical application related to the prediction of reflective judgment using high school and college performance measures.     

Reflection-Impulsivity in Mexican Children: Cross-Cultural Relationships

Urban Mexican children aged 5 (n = 23) and 9 (n = 87) years were given the Matching Familiar Figures Test (MFFT). The results indicate that the MFFT was a valid test of cognitive style for Mexican children. The younger children's MFFT performance was characterized as fast and inaccurate in relation to the older children's performance, which was slower and more accurate. Cross-cultural comparisons of Mexican MFFT scores with normative data from America, Japan, and Israel indicated that Mexican children were relatively impulsive in cognitive style in relation to children of other cultures. Potential factors contributing to these cross-cultural differences are discussed here.     

Learning Under Conditions of Action Information Feedback

Methodological and empirical issues in research on action information feedback (AIF) are discussed, with particular reference to the procedures and results of Annett (1970). Positioning responses practiced under conditions of AIF training are learned, though generally less well than under terminal IF conditions. Effects obtained as a result of AIF training may be subject to variations in movement extent required, gain and other transformations, frequency, temporal locus, and mode of augmentation, many aspects of which remain to be systematically studied.     

Medical slang in British hospitals

The usage, derivation, and psychological, ethical, and legal aspects of slang terminology in medicine are discussed. The colloquial vocabulary is further described and a comprehensive glossary of common UK terms provided in appendix. This forms the first list of slang terms currently in use throughout the British medical establishment.     

Focusing on fear: Attentional disengagement from emotional faces

Evidence suggests that anxiety is associated with a shift of visual attention toward threatening stimuli in the environment, such as facial expressions (Mogg & Bradley, 1999). More recent evidence, however, indicates that anxiety may be better characterized by a failure to rapidly disengage the visual attention system away from threat-related facial expressions (Fox, Russo, Bowles, & Dutton, 2001). The present study further investigates this delayed disengagement hypothesis. Results show that high trait-anxious individuals, in contrast to low trait-anxious individuals, take longer to classify peripheral target letters when fearful facial expressions were presented at fixation relative to sad, happy, or neutral expressions. These findings demonstrate a specific tendency to dwell on fear-relevant stimuli, as opposed to negative information in general. These findings are considered from an evolutionary perspective and the possible role of delayed disengagement from threat in the maintenance of anxiety states is also discussed.     

Screening for Significant Behavior Problems in Diverse Young Children Living in Poverty

The development and use of first line screening instruments is an essential first step in assessing behavior disorders in very young children. The Early Childhood Behavior Screen (ECBS) is a parent-report measure for behavior disorders and is normed on young children (1–5 years old) living in poverty. The current study presents psychometric support for the discriminative validity of the ECBS’s 10-item Challenging Behavior Scale (CBS) as a first-line screener for externalizing behavior problems for preschool aged-children in poverty. The study’s sample included 673 participants (M age years = 2.81; 63.2 % male; 65.8 % African American) that all met the federal definitional standard for living in poverty. A confirmatory factor analysis was run to provide support for the ECBS factor structure. Receiver operating characteristics (ROC) curve analyses were used to test the CBS’s ability to distinguish between 428 clinic-referred children and 245 non-clinic-referred children. Results showed an acceptable fit model for the ECBS, providing further evidence of its construct validity. Optimal cut-scores by child age derived from the ROC curve analyses were provided with corresponding levels of sensitivity, specificity, and positive and negative predictive values. Sensitivity rates for cut scores ranged from 0.76 to 0.83 and specificity rates ranged from 0.88 to 0.95. Acceptable test–retest reliability and good internal consistency also was observed. The CBS quickly identifies young children from low-income, urban, diverse populations that may be at-risk for developing significant behavior disorders and should be considered by health care professionals who work with very young children.     

Time perspective, depression, and substance misuse among the homeless

Using the Zimbardo Time Perspective Inventory (ZTPI; P. G. Zimbardo & J. N. Boyd, 1999), the authors found that homeless people, in comparison with a control group, had a significantly more negative outlook concerning their past and present as evinced by high Past-Negative and Present-Fatalistic scores and low Past-Positive scores on the ZTPI. However, the homeless individuals were almost indistinguishable from control participants on measures of Present-Hedonism and Future thinking. The homeless individuals had significantly higher levels of depression, with 31 out of 50 (62%) reaching criteria for probable depression. However, this finding was unrelated to their atypical time perspective. There was no significant relation between substance misuse and time perspective. Despite their current difficulties, including depression and drug abuse, the homeless individuals maintained a propensity toward future thinking characterized by striving to achieve their goals.     

Texture discrimination and the analysis of proximity.

A major theory of early visual processing has recently been proposed by Marr, which considers a number of aspects of visual perception in great detail, including grouping and texture discrimination. New phenomena associated with texture discrimination are described and experiments reported which allow a preliminary comparison of Marr's theory, as it applies to texture discrimination, with more established theories such as that due to Julesz. One experiment produced results which are clearly consistent with Marr's account, but the ability of his theory to deal with additional data on region suppression is not established. The theory of the analysis of proximity relations proposed by Fox offers a broadly satisfactory account of many texture perception results, while relying on the more fundamental parts of Marr's theory of primitive visual processes to deal with the remainder. A further attraction of proximity analysis is that it may shed new light on the classical paradox of symmetry perception. Some ways in which the preliminary proximity analysis model is incomplete are discussed, and it is concluded that development of the model may be profitable for theories of early visual processing.