A method for normalizing students' scores when employing multiple graders

Teachers of large classes often employ multiple graders to score student work. Even when appropriate measures are taken to insure that scoring by different graders is consistent, inconsistencies nevertheless occur. To adjust for them, instructors sometimes normalize grades mathematically, typically by scaling each grader group's score to an average of points earned. Scaling to an average has undesirable traits, including the difficulty of convincing students that it is fair. We developed an easy-to-explain method that adjusts scores so that the average number of points lost by students in each grader's group is the same. We discuss how to compute the adjustment and its advantages and limitations.