Rasch testlet model and bifactor analysis: how do they assess the dimensionality of large-scale Iranian EFL reading comprehension tests?

Abstract Rasch testlet and bifactor models are two measurement that could deal with local item dependency (LID) in assessing the dimensionality of reading comprehension testlets. This study aimed to apply real response data Iranian EFL tests compare validity corresponding parameters unidimensional multidimensional models. The collected from section national university entrance examinations 2016 2018. Various advanced packages R system were employed fit unidimensional, multidimensional, exploratory confirmatory Then, estimated effects identified; moreover, goodness indices parameter correlations for different calculated. Results showed all small but non-negligible Moreover, superior terms fit, whereas model better explained factor structure tests. However, difficulty more consistent than had substantial implications methods dealing LID reference testing.