Sunday, January 17, 2010

The Signaling Function of Grades

Market Power points us to an interesting discussion of the dual-purpose signal contained in a grade.

A person may be lazy, may make unrealistic goals, lacks an innate ability to learn, lacks the ability to learn quickly, etc. A grade conveniently wraps up all this information in one package.

Peter Bjornson thinks that this should not be the case. According to a report, he says:
... if a teacher deducts 10 or 20 per cent because a student turns work in late, then that mark is not "an accurate indicator of what the student has learned or achieved" [and] ". . . marks should reflect the student's achievement and should not be distorted as a result of work habits, attitudes or behaviours.

Phil points out:
Consider two people, Andy and Ben. Andy got an A in statistics and Ben got a B. Each of them got all the questions correct, indicating they learned the same amount of information. The only difference between them is that Ben is lazy and didn't feel like doing his stats work in a timely fashion while Andy has a solid work-ethic. Who is likely to make the better employee?

Obviously, Andy, but there is a more difficult question here: Consider now Ben and Candice, both of whom got B's. Ben got his B because he did not meet the deadlines, but knew all of the material; Candace got her B because, while she turned in all of the work, she did not do as well on the exams. Now whom would you rate as the better employee? I would say Candice, since for all of Ben's potential, he is unreliable. Some might make the other argument - Ben is the more talented candidate.

Other issues not considered in either context is the burden placed on the instructor by having to grade work and provide feedback when work is turned in sporadically or the fact that this approach would implicitly tax those students who turn work in according to the deadlines specified (if in fact any students choose to do that once deadlines are effectively dropped). The quality and timeliness of the feedback provided to the entire class would almost certainly suffer if this sort of thing caught on.