Psychometric characteristics and response times for one-best-answer questions in relation to number and source of options

Abstract

Background: The research reported here investigated the impact of number and source of response options on the psychometric characteristics and response times for one-best-answer MCQs.

Method: Ninety sets of MCQs were used in two studies; numbers of options in base versions of items ranged from 11 to 25. For each set, a United States Medical Licensing Examination Step 2 item-writing committee selected the five options viewed as most appropriate. For 40 used sets, two NBME staff constructed five- and eight-option versions to maximize item discrimination. All versions of items were embedded unscored on 2003-04 Step 2 test forms.

Results: Versions of items with more options were harder and required more testing time; no differences in item discrimination were observed in either study, but previous versions of the items in extended matching format were more discriminating than those used in the study.

Conclusion: Use of smaller numbers of options (and more items) results in more efficient use of testing time.