Hi Leslie: Interrater reliability is a technical term that defines the action of different individuals rating (or grading) an assignment. If there is high reliabilty, that would suggest there is a good chance that mutltiple graders would arrive at the same score. There are two components in play: one is the grading system and the other is the instructors that use the system. One or both could contribute to evaluating or assessing individual student performance inconsistently. I try to teach to the predefined student learning objectives, then measure how successful the student was in achieving those objectives. But I'll admit, there are many factors, several of which you've identified. Regards, Barry