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

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.

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.

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.

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