Applications of Item Response Theory to Non-Cognitive Data

We investigated the psychometric properties of the subscales of the Self-Perception Profile for Children with item response theory (IRT) models using a sample of 611 children. Results from a nonparametric Mokken analysis and a parametric IRT approach for boys (n = 268) and girls (n = 343) were compared. We found that most scales formed weak scales and that measurement precision was relatively low and only present for latent trait values indicating low self-perception. The subscales Physical Appearance and Global Self-Worth formed one strong scale. Children seem to interpret Global Self-Worth items as if they measure Physical Appearance. Furthermore, we found that strong Mokken scales (such as Global Self-Worth) consisted mostly of items that repeat the same item content. We conclude that researchers should be very careful in interpreting the total scores on the different Self-Perception Profile for Children scales. Finally, implications for further research are discussed. This chapter has been accepted for publication as: Egberink, I. J. L., & Meijer, R. R. (in press). An IRT analysis of Harter’s SelfPerception Profile for Children or why strong clinical scales should be distrusted. Assessment.