Evaluating multiple-choice exams in large introductory physics courses

The reliability and validity of professionally written multiple- choice exams have been extensively studied for exams such as the SAT, graduate record examination, and the force concept inventory. Much of the success of these multiple- choice exams is attributed to the careful construction of each question, as well as each response. In this study, the reliability and validity of scores from multiple- choice exams written for and administered in the large introductory physics courses at the University of Illinois, Urbana- Champaign were investigated. The reliability of exam scores over the course of a semester results in approximately a 3% uncertainty in students' total semester exam score. This semester test score uncertainty yields an uncertainty in the students' assigned letter grade that is less than 1/3 of a letter grade. To study the validity of exam scores, a subset of students were ranked independently based on their multiple- choice score, graded explanations, and student interviews. The ranking of these students based on their multiple- choice score was found to be consistent with the ranking assigned by physics instructors based on the students' written explanations (r > 0.94 at the 95% confidence level) and oral interviews (r= 0.94(-0.09)(+0.06)).