Wahyu Widhiarsoa, Bambang Sumintono

Abstract

This study examined to what extent participants who produce aberrant responses were in fact outliers in statistical analysis. Participants of this study were high school students (N = 2983) who filled out three personality questionnaires. Response aberrance for these instruments was detected using infit, outfit, and person-fit statistics under Rasch modeling, all of which reflect the degree to which response patterns conform to the model. According to the person-fit cutoff, participants were divided into three categories: overfit, fit, and underfit. Mahalanobis Distance (MD) was used to identify participants classified as outliers, based on a simple regression analysis. Analysis of variance highlighted significant differences between these three categories. The study found that underfit persons were more likely exhibited higher MD values than overfit or fit persons, meaning that they tended to perform as outliers. The correlation coefficients between two variables considerably increased after underfit persons were excluded in subsequent analyses. Another result showed that participants tended to consistently produce aberrant responses across the questionnaires, but that they did not consistently perform as outliers.

Keywords: Aberrant response; Person-fit statistic; Outliers; Rasch model

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Wahyu Widhiarso

Abstract

This study expands upon previous investigations regarding factors that affect individual ability to provide accurate responses via self-report measures. Specifically, the present study investigated the relationship between cognitive ability and response inaccuracy (aberrance), the hypothesis being that response inaccuracy on personality self-report was affected by cognitive ability. Cognitive abilities were measured using the Intelligence Structure Test; IST-70 and self-report accuracy was measured using the Coopersmith Self-Esteem Inventory (CSEI). Both instruments were administered to 11th and 12nd-grade students from 14 schools in Indonesia (N = 1,674). The W-statistic, a person-fit statistic in Rasch modeling, was employed to identify inaccurate response patterns on the CSEI. Logistic regression showed significant effects for cognitive and verbal abilities on individual response accuracy on the CSEI: individuals with higher cognitive abilities were more likely to produce accurate responses than those with lower cognitive abilities. In addition, the consistency of individual response accuracy ranged from low to high depending the characteristics of the specific item. Respondents demonstrated high consistency in their ability to give accurate responses within the same measurement for similar items.

Keywords: Cognitive abilities; Person-fit statistic; Accurate responses

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