Validation and Group Comparison of the Revised Systems Thinking Instrument (Re-STMI) Using Item Response Theory: High School vs. University Students

초록

This study aimed to validate the Revised Systems Thinking Measuring Instrument (Re-STMI) for high schooland university students and examine the differences between the two groups. Data were collected from 475 high schoolstudents and 340 university students. Analyses were conducted using the Rating Scale Model of Item Response Theoryand traditional Classical Test Theory methods including internal consistency reliability and independent-sample t-tests. Thefindings are as follows: First, the Rating Scale Model analysis indicated that students with higher levels of systemsthinking were more likely to choose the highest score (5) for each item, and the item distribution exhibited a normalpattern around the mean item difficulty. Average systems thinking ability was higher among university students (1.21) thanamong high school students (0.94). Second, Differential Item Functioning (DIF) analysis showed that the items functionedequivalently across the two groups. Third, the internal consistency reliability of the instrument, based on Classical TestTheory, was high (Cronbach’s = .866). Additionally, the independent samples t-test revealed a statistically significantdifference in the mean scores between the groups (p< .001). Based on these results, the instrument was verified to bevalid through both Item Response Theory and Classical Test Theory frameworks. Therefore, the Re-STMI can be utilizedin future research on systems thinking in various educational contexts.

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