Assessing the stability of principal components using regression

This paper presents an analysis, based on simulation, of the stability of principal components. Stability is measured by the expectation of the absolute inner product of the sample principal component with the corresponding population component. A multiple regression model to predict stability is devised, calibrated, and tested using simulated Normal data. Results show that the model can provide useful predictions of individual principal component stability when working with correlation matrices. Further, the predictive validity of the model is tested against data simulated from three non-Normal distributions. The model predicted very well even when the data departed from normality, thus giving robustness to the proposed measure. Used in conjunction with other existing rules this measure will help the user in determining interpretability of principal components.The authors would like to thank the four anonymous reviewers and the two editors for their valuable comments. Atanu R. Sinha gratefully acknowledges the research support received from the Marketing Studies Center, AGSM, UCLA. Send requests for reprints to Atanu R. Sinha, B418 Gold Hall, 110 Westwood Plaza, Los Angeles, CA 90095.     

Reply to Chrzan’s comments

1 This paper discusses the following works: Alvin Plantinga,The Nature of Necessity, Oxford University Press 1974, Chapter 9 Section 11; Keith Chrzan, ‘Plantinga on Atheistic Induction,’Sophia Vol 27 No. 2 (July 1988), 10–14; Bruce Langtry, ‘God, Evil and Probability,’,Sophia Vol 28 No. 1 (April 1989), 32–40; and Keith Chrzan, ‘Comment on Langtry's “God, Evil and Probability”,’Sophia Vol 32 No. 2 (July 1993), 54–58. The numbering of propositions throughout is the same as in my earlier paper. All page references to Chrzan are to his second paper.     

Public knowledge,attitudes, and beliefs about homeless people: Evidence for compassion fatigue?

Media reports suggest that the public is becoming impatient with the homeless—that so-called “compassion fatigue” has gripped the nation. This characterization of public sentiment could have important policy consequences—restrictive measures can be justified by growing public impatience, and progressive housing policies seem infeasible within a hostile climate of opinion. But evidence to support the compassion fatigue notion is anecdotal. We examine the issue by tracking the results of public opinion polls and by reporting detailed evidence from a nationwide random-digit dial telephone survey (N=1,507) concerning knowledge attitudes and beliefs about homeless people. To be sure, the public sees homelessness as an undesirable social problem and wants something done about it. However, although the homeless are clearly stigmatized, there is little evidence to suggest that the public has lost compassion and is unwilling to support policies to help homeless people.     

Parallel short forms of the family of origin scale: Evidence of their reliability and validity

Two parallel short forms of the Family of Origin Scale were developed from data provided by 69 women and 63 men who completed the full Family of Origin Scale along with a variety of measures of family-of-origin characteristics. Data on the reliability and validity of the short forms are provided and discussed. The results indicate that both short forms are strongly and significantly correlated with each other and with the full-scale version of the FOS and that they share its reliability and validity characteristics to a very high degree.     

A behavioral link between the oculomotor and cardiovascular systems

Although the eyes and the heart serve very different purposes, each receives autonomic innervation. Capitalizing on recent theoretical and technological innovations in the understanding and assessment of oculomotor and cardiovascular behavior, three experiments measured behavioral covariation between the oculomotor and cardiovascular systems. Measures of dark focus and dark vergence indexed oculomotor tone, and the spectral decomposition of variations in heart rate indexed cardiovascular control mechanisms. In Experiment 1, individual differences in cardiovascular parameters could predict individuals’ dark vergence (R²=.806) but not their dark focus (R²=.404). In Experiment 2, the same parameters were measured from subjects who experience either panic attacks (n=11) or blood phobia (n=9). Heart rate was positively correlated with dark vergence and the two subject groups were separable based on both oculomotor and cardiovascular variables. Using a within-subjects approach, Experiment 3 found that both dark vergence and dark focus tended to be nearer during sympathetic dominance of the heart than during parasympathetic dominance, within-subjects variations in cardiovascular parameters could predict dark focus, and between-subjects variations in interbeat intervals could predict dark vergence. Shared patterns of autonomic activation may be responsible for this eye-heart link.     

The use of consultation in psychological practice: ethical, legal, and clinical considerations

The importance of consulting with other professionals to maintain acceptable standards of care is well documented in many health care professions. However, evidence indicates that many psychologists fail to utilize consultation when needed, and that consultation use varies along dimensions such as the education and training of the consultee, the type of setting, number of years in practice, and proximity to available consultants. In this article, we review the research on the use of consultation by psychologists as well as other health care professionals. We discuss the clinical, ethical, and legal implications of seeking consultation as a professional psychologist. Finally, a detailed and practical model for the regular use of consultation is given to improve the routine use of consultation in clinical practice.     

Racial Categorization and Stereotype-Based Judgments About Homeless People1

The present study uses a social-cognitive paradigm to examine the association between racial categorization and stereotype-based judgments about homeless people. The study uses data from a national White subsample (N= 1,221) surveyed about attitudes toward homeless/homeless mentally ill people. It was hypothesized that individual differences in perceptions of the representativeness of Blacks in the homeless population, as measured by subjective estimates of the percentage of Blacks, would be associated with the enhancement of racially relevant negative stereotypes about homeless people. A secondary hypothesis was that perceptions of the representativeness of Blacks would be more strongly associated with the stereotype of homeless people as dangerous than with the view of them as lazy. The results support these hypotheses.