Robust mean and covariance structure analysis through iteratively reweighted least squares

Robust schemes in regression are adapted to mean and covariance structure analysis, providing an iteratively reweighted least squares approach to robust structural equation modeling. Each case is properly weighted according to its distance, based on first and second order moments, from the structural model. A simple weighting function is adopted because of its flexibility with changing dimensions. The weight matrix is obtained from an adaptive way of using residuals. Test statistic and standard error estimators are given, based on iteratively reweighted least squares. The method reduces to a standard distribution-free methodology if all cases are equally weighted. Examples demonstrate the value of the robust procedure.The authors acknowledge the constructive comments of three referees and the Editor that lead to an improved version of the paper. This work was supported by National Institute on Drug Abuse Grants DA01070 and DA00017 and by the University of North Texas Faculty Research Grant Program.     

Analog scale,magnitude estimation,and person trade‐off as measures of health utility: biases and their correction

Subjects judged the disutility of health conditions (e.g. blindness) using one of them (e.g. blindness+deafness) as a standard, using three elicitation methods: analog scale (AS, how bad is blindness compared to blindness+deafness?); magnitude estimation (ME, blindness+deafness is how many times as bad as blindness?); and person trade‐off (PTO, how many people cured of blindness is as good as 10 people cured of blindness+deafness?). ME disutilities of the less bad condition were smallest, and AS was highest. Interleaving PTO with ME made PTO more like ME. AS disutilities were inconsistent with direct judgments of differences between pairs of conditions. ME and PTO judgments were internally inconsistent: e.g. the disutility of one‐eye‐blindness relative to blindness+deafness was larger than predicted from comparison of each to blindness. Consistency training reduced inconsistency, increased agreement between AS and PTO, and transferred from one method to the other. The results support the use of consistency checks in utility elicitation. Copyright © 2001 John Wiley & Sons, Ltd.     

Expectancy‐effects without expectancies: Illusory correlations based on cue‐overlap

Expectancy‐based illusory correlations have been observed in numerous experiments. Simulations using the connectionist computer model BIAS (Fiedler, 1996 ) show that such illusory correlations may not always reflect expectancy biases but influences of similarity via cue‐overlap. Cue‐overlap means that some of the probabilistic cues that indicate the presence of one variable are also indicative of another variable. In an experiment, participants learned two novel concepts pertaining to a fictitious painter and a fictitious artistic style in separate runs. Both concepts were defined by multiple probabilistic cues observable in paintings. For half the participants, the cue systems underlying the perception of the two concepts overlapped, whereas for the other half they did not. In addition, we manipulated whether or not participants expected a positive contingency between artist and artistic style. In the second part of the experiment, a series of paintings was presented that constituted an objective zero correlation between artist and artistic style. Participants' subsequent contingency judgments were assessed by direct and indirect measures. Data analyses revealed main effects for expectancy induction and cue‐overlap but no interaction on the direct measure and nearly identical results on the indirect measure. Thus, cue‐overlap and expectancy induction independently triggered the development of illusory correlations. Copyright © 2000 John Wiley & Sons, Ltd.     

Prevention,the appropriate target of infant psychotherapy

The aim of this paper is to evaluate the case for preventive interventions in infancy aimed at the reduction of childhood psychopathology. The paper considers the terminology of prevention and the case for prevention in infancy. It is argued that increased knowledge concerning the developmental pathways involved in many psychological disorders opens the door to prevention initiatives. An overview of recent prevention trials is provided and the implications from treatment evaluation studies are explored. The case for prevention of conduct disorders is taken as an illustration of the potential for interventions in infancy. A developmental model of conduct disorder implicates a vicious cycle of parent–child interactions, a process that may arguably be preempted by early intervention. Three modalities are considered in detail: (a) early parent training; (b) the enhancement of attachment security; and (c) the facilitation of the development of reflective function. Studies in each of these areas are reviewed. The paper concludes that increased emphasis on the prevention aspect of infant mental health interventions is justified and desirable. © 1998 Michigan Association for Infant Mental Health     

Do you feel better or worse? The validity of perceived deviations of mood states from mood traits

The advantages of assessing self‐perceived deviations of mood states from mood traits in cross‐sectional as well as longitudinal studies are discussed in detail. The validity of self‐perceived mood deviations is analysed in a longitudinal study with three occasions of measurement and 176 participants. In order to assess self‐perceived mood deviations, participants rated the deviation of their momentary mood from how they felt in general with respect to 32 mood adjectives belonging to three mood scales (pleasant–unpleasant, calm–restless, awake–sleepy). Furthermore, mood states, mood traits, and other personality variables (hedonic level, neuroticism, extraversion, openness, agreeableness, conscientiousness) are assessed by self‐report. Using models of latent state–trait theory, it is shown that the self‐perceived mood deviation scales are reliable (reliabilities between 0.73 and 0.95) and sensitive to occasion‐specific fluctuations (occasion specificities between 0.38 and 0.72). The self‐perceived deviation scales show high correlations with latent occasion‐specific deviation variables defined on the basis of repeatedly measured mood states (high convergent validity). In contrast to self‐reported mood states, however, self‐perceived mood deviations show much smaller and in most cases non‐significant correlations with personality variables (high discriminant validity). Furthermore, it is shown that self‐perceived mood deviations can be used to suppress stable situation‐specific variance in mood traits defined as aggregated states. Therefore, it can be demonstrated that including self‐perceived mood deviations in analyses on mood–personality associations enhances the association coefficients considerably. Finally, the implications of the results for the individual assessment of mood deviations, as well as for studies on affect and personality, are discussed. Copyright © 1999 John Wiley & Sons, Ltd.