Standardization of Intrinsic Motivation for Free Study Scale

This study aimed to standardize and examine the psychometric character- ristics of intrinsic motivation of free study scale in Tehran. The instrument was administered on 1000 people (15 and older) in 2014-2015 which were selected by multistage cluster sampling method. The type of research is psychometric based on classical test theory (CTT) and item response theory (IRT). Data analysis, reliability, hierarchical confirmatory factor analysis, percentile ranks, Z and t scores were performed. Reliability of the total Scale was calculated using the Cronbach's alpha 0.92, Guttman’s Lambda 0.92, classified alpha 0.92, split-half 0.75, Omega 0.88, Theta 0.93, Composite 0.91, local0.84. Confirmatory factor analysis shows that the structure of scale has acceptable fit to the data and all indicators confirm the fitness of the model. The norms table was prepared and Z, t, and percentages were calculated. Based on research findings it can be concluded that intrinsic motivation of free study tool has stability, internal consistency, reliability and validity and it can be used in Iranian population.