Introduction and analytical comparison of classic test theory (CTT) and item response theory (IRT) in psychometrics

Abstract

The study has dealt with a brief introduction and analytical comparison of two major psychometrics theory i.e. classic test theory and item-response theory along with their privileges and limitations. Although the classic test theory was founded in early part of the twentieth century. Its numerous limitations made the specialists think of means to remove these limitations. In the process of seeking solutions for removal of weaknesses in classic theory, they came up with a new theory in the 1950s which became known as time-response theory. Inspite of its gradual completion and apparent removal of limitations in the course of time, IRT has never been free from limitation and it has always been subject to some objections. For the time being each of these theories has more or less advocates among the educational ,psychological specialists and those who are related to psycho-educational measurements .These theories are not duly known in Iran ,so the present study tries to introduce these theories along with their weaknesses and strengths ,common and different points.

Keywords

• discrimination parameter
• difficulty parameter
• information function
• item characteristic function
• psychometric theories
• item-response theory (irt)
• classic test theory (ctt)
• asymptote parameter
• item characteristic curve (icc)