Distractor Functioning in Modified Items for Test Accessibility

Effective distractors in multiple-choice items should attract lowerability students, those with misconceptions or limited knowledge and skills, becausethey are based on common misconceptions or errors in logic. A large, multi-state dataset collected for a quasi-experimental study on test modifications was analyzed tomeasure the impact on distractor functioning. The key modification of interest was theremoval of the weakest of three distractors, from 39 items in reading and 39 items inmathematics. Distractor functioning was neither systematically improved norsystematically weakened through the modification process. However, more than 70% of thedistractors became more discriminating. A moderate correlation between distractorselection rate and distractor discrimination, in mathematics, may have indicated thatthe modified items were being missed by the appropriate students. Implications of thesefindings for test developers are discussed