Assistant Professor of Applied Linguistics, Islamic Azad University, Mashad Branch, Iran
Equating test scores is an important issue in large scale testing. Almost all standardized tests have several forms which vary in difficulty. New forms are written and added every year. When the items in different forms of a test vary in difficulty, direct comparison of test-takers who have taken different forms and are at the same ability level is not possible; hence, the issue of test fairness arises. In such situations there is a need for equating test scores so that standards can be maintained year to year. That is, there is the need to adjust the scores for the difficulty of the test forms and report a scaled score that is comparable across all forms of the test. In this study, two forms of a reading comprehension test were equated and the pass/fail decision consistency was investigated under two conditions of with and without equating. Concurrent common item equating with one parameter Items Response Model (IRT) was used to equate the two test forms. Results showed that the lack of equating leads to unfair pass/fail decisions. The implications for high-stakes large scale testing are thus discussed.