Psychometric Properties of State Level Subjective Vitality Scale based on classical test theory and Item-response theory

The purpose of the present study was to investigate the factor structure and Item-Response parameters of State Level of Subjective Vitality Scale. The research design was correlational, and the statistical population consisted of students of the Shahid Beheshti University of Tehran. Sample group including 240 students were selected through multi-stage sampling and completed Subjective Vitality scale. Internal consistency, exploratory and confirmatory factor analysis, discrimination and threshold parameters and Item and test information curves were analyzed. Results showed that both 7 and 6 Items form of the state level of subjective vitality scale show the structure of an agent with an explained variance of 67.19 and 75.04%. Confirmatory validity was confirmed. Cronbach's alpha coefficients for the scales varied from 0.91 to 0.93 and split half coefficients varied from 0.91 to 0.92, respectively. The Item-Response parameters were also at the optimum level. It seems that the state level subjective vitality scale, and in particular the structure of its 6 item versions, has good reliability and validity in students.