Psychometric characteristics and response times for content-parallel extended-matching and one-best-answer items in...

This study investigated the impact of item format and number of options on the psychometric characteristics (p values and biserials) and response times for multiple-choice questions (MCQs) appearing on Step 2 of the United States Medical Licensing Examination.

In all, 192 MCQ items were used in the study. Each item was presented in two formats: in a two-item extended-matching set and as an independent item. For the extended matching format, there were two versions: a base version that included all options (10 to 26) and an 8-option version. For the independent-item format, there were three versions: a base version that included all options, and 8-option and 5-option versions created by a group of physicians that selected options without information about examinee performance. All items were embedded in unscored sections of the 2005-06 Step 2 test forms.

Versions of items with more options were harder and required more testing time; no differences in item discrimination were observed. Mean response times for items presented in the extended-matching format were lower than for those presented as independent items, primarily because of shorter response times for the second item presented in a set.

Use of the extended-matching format and smaller numbers of options per item (and more items) should result in more efficient use of testing time and greater score precision per unit of testing time.