Self-control has drawn substantial attention from researchers in both psychological and educational settings, and data shows that over 3% of articles from PsycInfo database include the keywords of “self-controlâ€, “self-disciplineâ€, and their relevant terms from 2009 to 2010 (Duckworth & Kern, 2011). Researchers studied self-control not only because it “holds important keys†to understanding the nature of themselves, but practically, because it plays an important role in predicting academic achievement for students, job performance of adults, and individual’s delinquent behaviours (e.g., drug abuse, violence, and crime) (Bakker, Demerouti & Brummelhuis, 2012; Baumeister, Vohs, & Tice, 2007; Duckworth & Kern ,2011). These findings may promote the development of self-control assessment tools, and help schools or other social organisations to evaluate this ability. This study applied item response theory (IRT) models to collect validity evidence of the Middle School Students’ Self-control Ability Questionnaire (MSSSAQ), which was a self-report questionnaire, designed for assessing 7^th-10^th graders’ self-control abilities. Rasch measurement was adopted as the statistical method for the validation process, considering that previous validity evidence was collected based on classical test theory (CTT). MSSSAQ was administrated to a convenience sample of 703 10^th graders, and they were recruited from a provincial level key high school, Shandong Province, China. Results showed that content based validity evidence could be derived from analysing the item-person map, point-measure correlations of items and categories. Internal structure based validity evidence could be collected by analysing the internal reliability, unidimensionality, and differential item functioning. The findings highlight the importance of multiple sources of validity evidence based on IRT and CTT perspectives for the purpose of improving the development of MSSSAQ.

Keywords: self-control, Rasch analysis