The Relationship between CTT and IRT Approaches in Analyzing Item Characteristics

Abstract

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.