Gerard H. Maassen

Suppressor Variables in Path Models Definitions and Interpretations

Suppressor variables are well known in the context of multiple regression analysis. Using several examples, the authors demonstrate that the different forms of the suppressor phenomenon described in the literature occur not only in prediction equations but also in the explanatory use of multiple regression, including structural equations models. Moreover, they show that the probability of their occurrence is relatively high in models with latent variables, in which the suppressed variable is corrected for measurement errors. Special attention will be paid to the two-wave model since this is particularly liable to the suppressor phenomenon. The occurrence of suppression in structural equations models is usually not foreseen and confronts researchers with problems of interpretation. The authors discuss definitions of the suppressor phenomenon, show how the unwary researcher can be warned against it, and present guidelines for the interpretation of the results.

Executive Functions in Preschool Children with Aggressive Behavior: Impairments in Inhibitory Control

The question whether executive function (EF) deficits in children are associated with conduct problems remains controversial. Although the origins of aggressive behavior are to be found in early childhood, findings from EF studies in preschool children with aggressive behavior are inconsistent. The current study aimed to investigate whether preschool children with aggressive behavior show impairments in EF. From a population-based sample, 82 preschool children who were showing aggressive behavior as indicated by scores at or above the 93rd percentile on the Aggressive Behavior Scale of the CBCL 1 1/2-5 were selected. These children with aggressive behavior were matched on IQ to a group of typically developing control children (N = 99). Six neuropsychological tasks were administered to assess set shifting, inhibition, working memory and verbal fluency. A factor analysis was conducted which yielded one clear factor: inhibition. Aggressive preschool children showed poorer performance on this inhibition factor than control children and boys performed worse on this factor than girls. This association between aggressive behavior and inhibition deficits was maintained after controlling for attention problems. In addition, gender differences in all EFs measured were found with boys exhibiting more impairment in EF than girls. These findings demonstrate that preschool children with aggressive behavior show impairments in inhibition, irrespective of attention problems.

The standard error in the Jacobson and Truax Reliable Change Index: The classical approach to the assessment of reliable change

Researchers and clinicians using Jacobson and Truaxs index to assess the reliability of change in patients, or its counterpart by Chelune et al., which takes practice effects into account, are confused by the different ways of calculating the standard error encountered in the literature (see the discussion started in this journal by Hinton-Bayre). This article compares the characteristics of (1) the standard error used by Jacobson and Truax, (2) the standard error of difference scores used by Temkin et al. and (3) an adaptation of Jacobson and Truaxs approach that accounts for difference between initial and final variance. It is theoretically demonstrated that the last variant is preferable, which is corroborated by real data.

Commitment and exploration as mechanisms of identity formation

We report a two-wave longitudinal study of 1,571 Dutch adolescents concerning the role of commitment and exploration in identity development. We used the Utrecht-Groningen Identity Development Scale to measure commitment and exploration in the domains of relational and societal identity. Our results can be summarized in three points. (1) Commitment and exploration are related processes in the development of identity. Adolescents with strong commitments also frequently explore them, and adolescents with low exploration in general have weak commitments. (2) The longitudinal stability of commitment and exploration has a medium effect size. For relational identity the stability of commitment is greater than that of exploration, but this is not the case for societal identity. The explanation we give for the lack of this difference in stability between commitment and exploration in societal identity is that the formative period for societal identity comes primarily at the end of adolescence. In that connection, we conclude that for present-day Dutch adolescents the formation of relational identity probably precedes that of societal identity. (3) In neither identity domain is commitment predictive of exploration three years later, nor is the reverse the case. We conclude that no long-term developmental sequentiality of commitment and exploration was found, but the results do not rule out the possibility of short-term developmental sequentiality.

Sustained Effects of Incredible Years as a Preventive Intervention in Preschool Children with Conduct Problems

The present study evaluated preventive effects of the Incredible Years program for parents of preschool children who were at risk for a chronic pattern of conduct problems, in the Netherlands. In a matched control design, 72 parents of children with conduct problems received the Incredible Years program. These families (intervention group) were compared with 72 families who received care as usual (control group). Two years after termination of the intervention, it appeared that observed and selfrated parenting skills were significantly improved in the intervention group. Likewise, in this group, observed child conduct problems showed sustained intervention effects. The decrease in observed critical parenting mediated the decrease in observed child conduct problems over time. In addition, it appeared that parental influence increased over time.

A parent questionnaire for distinguishing between reactive and proactive aggression in children

BackgroundEvidence suggests that reactive and proactive aggression can be distinguished on the basis of teacher-rating scales. In this article a newly developed parent-rated questionnaire that aims to distinguish between reactive and proactive aggression is evaluated with regard to its structure and validity.MethodIn study 1, a confirmatory factor analysis was performed on the data of 442 children aged 6–12 years of a general population. Study 2 examined the relations between the two forms of aggression and hostile intentions, expected outcome of aggression, ADHD symptoms and callous-unemotional traits in a sample of 40 normal and 40 disruptive behaviour disordered boys aged 8–12 years.ResultsThe confirmatory factor analysis showed that the two-factor model, unlike a singlefactor model, produced a reasonable fit to the data. The results of study 2 showed that the correlations between the different variables and reactive aggression differed from the correlations with proactive aggression in ways that were consistent with theoretical definitions and earlier findings.ConclusionThese results, in addition to those of earlier studies using teacher-rating scales, suggest that it is possible to make a valid distinction between reactive and proactive aggression using this newly developed parent-rated questionnaire.

Reliable change and practice effects: Outcomes of various indices compared

In this article the outcomes of three indices for the assessment of reliable change (RCIs) are compared: the null hypothesis method of Chelune, Naugle, Lüders, Sedlak, and Awad (1993), the regression-based method of McSweeny, Naugle, Chelune, and Lüders (1993), and a recently proposed adjustment to the latter procedure (Maassen, 2003). Simulated data demonstrated the importance of using large control samples. The regression-based method proved to be the most lenient in designating individuals as reliably changed, resulting in the most correct and the most incorrect designations. The adjusted procedure resulted in fewer correct designations and the lowest numbers of incorrect designations. Real-world data showed the same patterns.

Principles of Defining Reliable Change Indices

In this article, several salient measures for determining reliable change are scrutinized. The classic null hypothesis method is compared with more recent procedures based on interval estimation of the true change, including Kelley’s formula. The latter category of methods are shown to entail serious drawbacks. If Kelley’s formula is expanded to a null hypothesis method (including a correct treatment of the stochastic character of the sample information), the classic method reveals itself as a large sample approximation. We conclude that the classic method is undeservedly regarded inferior by the authors who proposed new indices.

Psychophysical precedents of migraine in relation to the time of onset of the headache: the migraine time line.

We conducted a prospective study of 19 female migraine patients who kept a diary four times per day at 8 AM, I PM, 6 PM, and 11 PM for 10 consecutive weeks. In the diary, the patients recorded the occurrence as well as the features and associated symptoms of their headaches. They also rated five mood states: alertness, tension, irritability, depression, and fatigue, as well as the quality of sleep and the incidence and stressfulness of daily hassles as measurements of stress. They quantified the variables through the use of 100‐mm visual analog scales.

Two-Dimensional Sociometric Status Determination with Rating Scales

Sociometric status is derivedfrom a concatenation ofjudgments at the individual leveL In previous articles, the authors argued that score attribution at this level (where one group member assesses another) is one-dimensional along the sympathy+-antipathy continuum. Two-dimensionality of sociometric status arises at the group level. It was shown that at this level, too, sympathy and antipathy are not two distinct dimensions but the poles ofjust one, the other being visibility (or impact). If one accepts the model of one-dimensional score attribution at the individual level, it would seem logical to base sociometric status determination on rating scales. In this article, a procedure for this is developed and a covering computer program (SSRAT) is introduced. Finally, the results of the current nomination methods and the proposed rating method applied in the same classroom groups are compared The results of the rating method appear to be more valid and more refined