The Relationship between CTT and IRT Approaches in Analyzing Item Characteristics.
Nabeel Abedalaziz, Chin Hai Leng · 2013
Most of the tests and inventories used by counseling psychologists have been developed using CTT; IRT derives from what is called latent trait theory. A number of important differences exist between CTT- versus IRT-based approaches to both test development and evaluation, as well as the process of scoring the response profiles of individual examinees. The purpose of this research is to compare the item difficulty and item discrimination of the Mathematical ability scale using CTT and IRT methods across 1, 2, and 3 parameters. The developed instrument was administered to tenth grade sample of N=602. The data gathered was analyzed for possible relationship of the item characteristics using CTT and IRT methods. Results indicate that the 3-parameter logistic model has the most comparable indices with CTT, furthermore, CTT and IRT models (1-parameter logistic model and 3-parameter logistic model) can be used independently or altogether to describe the nature of the items characteristics. Keywords: