A Comparison of Magical Ideation in Nonclinical Adolescent and Adult Groups : An Item Response Theory Based Differential Item Functioning Analysis

Abstract

Objectives : We examined magical ideation in adolescent and adult group by Magical Ideation Scale (MIS). We also explored how adolescents and adults respond differently to each items of MIS. Methods : 310 nonclinical adults and 310 Year 10 students participated in this study, and completed MIS and Symptom Checklist 90-revision (SCL-90-R). Total scores of MIS were compared between adults and adolescents. The item characteristics of MIS were evaluated by item response theory (IRT). Differential item functioning (DIF) was detected using the parameters of IRT. Results : Total score of MIS was higher in adolescents than in adults, but there was no statistical significance. Item 5, 10, 13, and 16 showed significant difference on item difficulty parameters and were identified as DIF. Among DIF items, item 5 was more dif ficult for adolescents than adults. Item 10, 13, and 16 were more difficult for adults than adolescents. The modified MIS score ex cluding 4 DIF items was significantly higher in adolescents than adults. Conclusion : The influence of age on response to DIF items should be considered when comparing MIS scores between adoles cents and adults. (Korean J Schizophr Res 2015;18:28-34)