Item Parameter Drift of the Self-Description Questionnaire I

Abstract

Abstract. The purpose of this study was to evaluate the psychometric properties of the Self-Description Questionnaire I (SDQI) with regard to children’s mathematics self-concept based on the item response theory (IRT) framework. The researchers adopted the IRT-based techniques for uncovering item-level characteristics including discrimination ( a parameter) and thresholds ( b parameters). The data for this study were drawn from the Early Childhood Longitudinal Study, Kindergarten Class of 1998–99 (ECLS-K) with a sample of 14,631 children. The IRT-based evaluations suggest that the SDQI items have sufficient discrimination, but insufficient item thresholds in assessing third- and fifth-graders’ mathematics self-concept. Thus, it is recommended that the current SDQI be reconsidered for its age appropriateness. In addition, affective items, which involve enjoyment, liking, and positive emotions, are found to be better indicators of self-concept than cognitive items, which involve perceived competence, ability beliefs, and self-efficacy. Results also indicate the presence of item parameter drift (IPD) in all SDQI items, suggesting beta change of the scale over time – children become more sensitive to the response anchors as they grow older. Findings of this study provide insights into the conceptualization and operationalization of academic self-concept, as well as practical implications for future use and development of self-concept measures.