Grading on a curve and The Case Against Education
I recently read The Case Against Education, which
argues that
education pays off for individuals mostly because it sends signals about intelligence and
conscientiousness,
not because it equips students with useful skills. Here's a puzzle which was not addressed in the book,
but may be solved by that
model.
My university courses were mostly graded on curves. I
think Advanced Placement exams are also graded on curves, but I'm less sure of this. At the time this
didn't
make sense to me. If the point of taking the courses was to gain skills, shouldn't there be an objective
scale
of how much skill a student gained? And shouldn't students be graded against this objective scale,
rather than
on how they place in the distribution of students who happen to take the exam on the same day as them?
Objective
grading seems especially feasible for technical courses like math, but I could imagine it being
plausible for
humanities courses like history as well.
But if the point of a school transcript is not so much
to say "Look at all these skills I acquired!", but rather to say "Here's where I am in the distribution
of
students who got this degree at this university", then the mystery is dissolved. The latter is obviously
more in
accordance with the signaling model.
Of course there are other reasonable explanations for
grading on a curve, even in technical courses. If imposed by the department or university, it can be
used as a
defense against grade inflation. I believe it had that effect at my undergraduate university, where some
departments had distributions that all professors were supposed to adhere to, and those departments had
generally lower grades. But again, wanting to maintain the same grade distribution over many years is
inconsistent with that grade being an objective measure of skill gained, unless we assume zero change in
pedagogical methods, how much knowledge students have coming in, or just random variation in class
achievement.