Item Statistics of Multiple Choice Physics Achievement Test Using Classic Test Theory and Item Response Theory

Abstract

This study examine the comparability of item statistics generated from the frameworks of classical test theory (CTT) and 2-parameter model of item response theory (IRT). A 40-item Physics Achievement Test was developed and administered to 600 senior secondary school two students, who were randomly selected from 12 senior secondary schools in Taraba State, Nigeria. Results showed that item statistics obtained from both frameworks were relatively similar. However, item statistics obtained from IRT 2-parameter model looked balanced than those from CTT. In addition, for item selection process, IRT 2-parameter model retained more items than CTT model. This result implies that test developers and public examining bodies should integrate IRT model into their test development processes. Through IRT model, test constructors would be able to generate stable items than in the CTT model used at present and at the end, the test scores of examinees will be more reliably estimated.