The problem is that humans have an innate desire - need even - to classify and quantify nearly everything. We want to know simply: What are the best cars? Who are the prettiest? What grades are good and what are bad?

It's the reason you get a web full of top 10 lists. Quick and easy evaluations of often subjective and arbitrary data.

We simply can't process the amount of information it takes to evaluate whether a child is doing well in school beyond said child being an absolute genius, a dismal failure or "somewhere in between".

So long as parents demand that they know whereabout in the "somewhere in between" spectrum their child stands, we'll have abstract and near useless grading mechanisms.

The problem is that the leter-grade system doesn't give this information. "A" could mean you're a super-genius, or a plain old genius, or a reasonably good student, or a so-so student at a place with severe grade inflation.

At my school (in Australia) we didn't have letter grades, we had a mark out of (say) one hundred combined with an indication of your ranking within the class. Bold, stark information which told you in no uncertain terms exactly how many people in your class or year were better than you. No doubt it was ego-destroying if you got "150/150", but pretty motivating if you got "11/150", and suitably rewarding if you got "1/150".

This wasn't continued through to the university level, but at least we still got a nice high-resolution mark on a 0-100 scale for each course. And the grades weren't too inflated, so any mark over 90 was a real achievement even for the top students. Getting 100 for any course was unheard of (not quite true, I did hear of somebody getting one once.)

I work at a university in the US now, and I'm really confused about why they still use such a low-resolution system for grading students.

Nor does it make much sense. I was 28/290 in high school, but voted "Most Likely to Succeed" at graduation. Now I'm a hacker in a successful startup. Obviously something other than my grades caused everyone to vote me over 27 other people. 5 of my classmates above me went to Harvard, 2 to Columbia, 2 to NYU, 1 to MIT, I went to a state school. I'm doing better than of them today. How did my classmates know that was going to happen? Not to mention in college I knew a couple valedictorians who wouldn't be #40 in our high school. So rank doesn't mean anything, and grades mean less.

I was an A- student in high school and a B student in college, but with all the extra time I had I hacked and read. The A+ students spent all their time working on their homework and learned nothing else. That has something to do with it.

Since a grade is supposed to correlate with how much you've learned, I'm not convinced higher resolution is necessary. It's already fuzzy how well any grade can represent actual knowledge, skills and experience gained.

Improving the precision doesn't necessarily improve the accuracy. But if improving the precision increases our confidence in the metric - without necessarily increasing it's accuracy - maybe we're better off not doing it.

If anything, it should be a lower resolution system. If you measure a distance by crudely pacing it off, you don't say it is "134.581234 yards". You say it is about 130 yards.

Consider the following questions in thinking about how many significant digits should be expressed in a grade:

* Go back through every homework and test for your entire college career, and have them re-graded by the professors involved. Or consider doing that for a sample of 50 or 100 students. By how much does the GPA change ?

* Go back through every homework and test for an entire college career, and have it re-graded by a commitee of 10 experts in the field, who must all agree on every problem's grade after consulation with each other. By how much does the GPA change ?

* Does the average grade given out by a professor or other grader change if they are in their first semester of grading / teaching, versus following semesters ? If they grade late at night versus early in the morning ? If the name on the paper being graded is that of a good or poor student ? ( Presuming it is the same paper for both students -- this study was done by two students I know, who agreed to copy each other's papers for a couple of grades and then confronted the biased teacher and were punished for it.)

Now, if you are putting so many significant digits on those GPA's that non-student related stuff such as which professor they were randomly assigned to comes into play, then you are just fooling yourself. And that's only considering how good grades are at predicting THEMSELVES.

And, if you want to consider how good grades are at predicting anything else, except maybe "will I get into medical school" and other explicitly grade-related questions, I think you end up ignoring them all together. I would only care about whether or not they graduated high school, which college to a very loose degree, and whether or not they finished college. The presence or absense of a master's degree does not seem to predict anything (except maybe good grades as an undergrad).

If you assign a number to anything, some people will become fascinated by it. If you made a video arcade game, where you pressed a button once and it gave you a random score between one and a million, some people would stand there feeding in quarters until they were at the top of the high scorers list.

If you think that the grading system is low-resolution, then you aren't trying to use grades to predict anything useful about people, you are just fascinated by a very expensive and time consuming video game.

Not that there's anything wrong with that.

Perhaps should not have a higher numeric resolution - but more dimensions.

Ranking within your class tells you just as little. Even worse, you'll be biased against schools filled with bright students.

The letter grade system is basically this:

A - 80-100 B - 70-80 C - 60-70 D - 50-60 F - Less than 50%

In terms of rebuttal, what scott_s said.

In the U.S.? I have always seen closer to this:

A 100-90 B 89-80 C 79-70 D 69-60 F 59-0

In Florida they mandated that an A be 100-94 to "raise standards" for education. You can imagine how much impact that really had.

Yeah, there are different versions... and I could be wrong. I gave the high school one since it's what I could remember off hand. Getting a "D" was just as bad as failing though.

In some places, sadly, getting a low B is considered 'failing'... In most of my classes, at least. But I suppose the pressure gets you to work more quickly and efficiently.

In grad school, we were specifically told not to get too many A's and to focus on publications. If some industrious type got mostly (or all) A's the next question from their committee was: Why aren't you working on publishing?

C's though were failing. Still, you had to try really hard to fail. The B's were inflated.

The difference is probably domains - a Ph.D. in cognitive neuroscience doesn't prepare you for much else than doing science. There, judgment for a tenure-track job begins and ends with publications. And no one will want to see grades and no CV ever includes them.

Computer Science is no different in terms of criteria for a tenure-track position. Well, publications is only half of it, grant money is the other half, but I imagine that's true for your field as well.

The CS departments I've been a part of don't expect students to publish much - if anything - until after most of their course work is done. That's usually about two years.

UNC Chapel Hill has an interesting grade system for grad students that emphasizes that grades don't matter much. There are only three major grades:

H (high pass),

P (pass), and

L (low pass).

Well, and and F, technically, but you are kindly asked to leave if you get an F.

You can have at most one L. You need to maintain a slightly above P average to be admitted to the PhD program.

I think it depends a lot on the school or the department.

When I was in grad school for physics, C+ was considered failing. Beyond that, we were specifically told, as long as we passed, grades didn't matter. It was of course quality of research that mattered.

I don't know how differently people faired with different GPA's coming out. I think employers mostly looked at publications and references. And I'm not far enough out to say who was "successful" yet.

The first CS department I was in didn't have quals. You had to maintain a 3.7 GPA over all course work to be admitted as a Ph.D. candidate, so grades did matter.

I wish I had started out in departments like some of you described. I started doing research my first year, and my grades suffered for it. I got three of those Bs, and I had to take an extra course just to be admitted as a Ph.D. candidate in that program. Luckily, I have since transferred to a different school.