Do peer instructors provide better explanations? Comparing perceived explanation quality between different instructor types

Universities use instructors with varying levels of physics expertise for undergraduate physics instruction, including faculty members, graduate teaching assistants, and undergraduate peer instructors. This study examines the effects of instructor type on students' ratings of explanation quality. We collected written explanations to common introductory physics questions from highly recommended instructors of each type. Students enrolled in an introductory physics course made pairwise comparisons of the written explanations until a rank order could be generated for each student participant. We determined if instructor type could determine placement in a student's rank order using ordinal regression. Using a relative placement algorithm, we extracted a general rank order for the explanations that reflects consensus opinion on the relative quality of the explanations. We present the results as a commentary on the relative effectiveness of different instructor types on providing explanations that students perceive as good explanations.