The AICPA uses IRT (Item Response Theory) for the objective portion of the examination. IRT is a well-established psychometric approach to scoring used by licensing and certification examinations that administer many different test forms. IRT scoring ensures that scores and pass or fail decisions based on scores from different examination forms are comparable. Based on the large amounts of data that are collected in pretesting, the difficulty level as well as other statistical characteristics of examination questions are known and taken into account in scoring.