Using Item Response Theory to Develop a Shortened Version of the Penn State Worry Questionnaire for Children

The PSWQ-C is a widely used international scale to measure worry traits in children and adolescents. It has been translated into several versions for use in different countries. The purpose of this study was to examine the psychometric characteristics of the Penn State Worry Questionnaire for Children (PSWQ-C) particularly three reverse-scored items, and to develop a shorter version of the PSWQ-C based on Item Response Theory (IRT) methods. 903 children and adolescents of different ages from China participated in the study. This study used the Graded Response Model (GRM) to fit the data and examined the IRT parameters of each item, Item Characteristic Curve, Item Information Functions, and Differential Item Functioning. Eight items with undesirable functioning were removed, while six items with good functioning were retained, resulting in a simplified version of the PSWQ-C. The abbreviated version of the PSWQ-C was subsequently validated for its reliability and validity. The results confirmed that the abbreviated scale is reliable and effective, with a Cronbach's alpha coefficient of 0.84, indicating good reliability. Regarding validity, the abbreviated version of the PSWQ-C demonstrated significant correlations with IUS-12 and MASC, both exceeding 0.60, which closely resembles the correlation of the original PSWQ-C with these two scales. Furthermore, the correlation between the two versions was 0.96, indicating that the abbreviated PSWQ-C can effectively replace the original version and has a broader range of applications.