An interesting find:
Grading Exams: 100, 99, ..., 1, or A, B, C?
PRADEEP K. DUBEY
State University of New York, Stony Brook
Yale University - Cowles Foundation
Cowles Foundation Discussion Paper No. 1467
We show that if students care primarily about their status (relative rank) in class, they are best motivated to work not by revealing their exact numerical exam scores (100, 99, ..., 1), but instead by clumping them in broad categories (A, B, C). * * *