Sometimes I'm reading an answer and it has a certain "smell" to it that I can't quite pinpoint, but makes me distrustful of the answer and I feel surprised to see it coming from a user with a high rep. The rep system is what it is, and I'm not arguing against it, but perhaps as a single metric it has too many interpretations. A high rep could mean someone who has a lot of quality questions and answers, but could also mean someone who scrapes a few rep from a large quantity of dubious-quality answers.
I heard once that in the baseball world, a player's batting average is taken into consideration more often than their ability to do homers. Regardless of whether that's true or not, would a "rep per answer" stat be useful? I think it should exclude questions with bounties, but of course that's debatable.
I also wonder if the actual display of such a batting average would cause more "meta-rep gaming" like strategic down-voting - griefers see a high batting average and automatically down-vote or some such...
Edit:
IMHO, a lot of the value in the rep system is to build literal reputation for a user. A high rep really does bring a bit of prestige, and user who has a high rep will probably (and rightfully) be proud of their rep. Having a high rep means something - why else do people do rep-whoring, or fastest-gun-in-the-west sort of stuff? Ask any user who has more than 5k rep if they'd be happy to have it reset to 1.
My point is that we shouldn't lead ourselves to believe that "the system is designed to produce good answers, nevermind if an answerer has high rep or not", because I don't buy it. Rep-whoring is a symptom of this, I think. A real reputation would be developed if a person is known to consistently produce good, thoughtful answers, and a single number at a glance just doesn't cut it. I guess my desire would be to have the users kept more honest with themselves, and I don't think a rep average is the answer but it does help with evaluating the users, not just the answers.
Only a very tiny percentage of users are on often enough to participate in the in-jokes and Jon Skeet fawning, the vast majority of users do not know that so-and-so is full of B.S. and that sort of thing. If you fast-forward a few years, SO will continue to get much more users and things like this will get more and more ambiguous. The average user will need a little more help figuring out who is trustworthy and who is not, and that need will increase as the community gets bigger and bigger.
Hopefully that makes sense. I feel like I've been ranting and that's never been helpful.
Edit 2:
devinb provided a very handy list for me to show why rep avg can be a great metric to use: His list is this:
- There are people with many answers in niche tags who would have low rep-per-answer.
- There are people who have many answers in very popular tags who aren't fast enough to get huge upvotes.
- There are people who answer very few questions, but answer them very very thoroughly and get huge upvotes.
- There are people who only answer joke-type questions and get huge (undeserved) upvotes.
- There are people who put off-the-cuff answers on a lot of questions and get a few upvotes.
He also provides a list of things he would have to do in order to increase his rep average:
- Delete my lower voted posts (even if they are still valid and helpful)
- Ignore any low-view tags or questions
- Create a sock-puppet user to upvote all my posts
- Downvote other users to make my posts look more attractive
Here are my responses:
niche areas (gnostradamus also mentions this in his answer): if you're answering questions in a niche area, your rep is already low relative to the # of answers you've posted. You shouldn't be surprised by a corresponding low average. Working in a niche area and providing quality answers anyway despite a low rep score means you wouldn't care about a low rep average either.
many answers, but in popular tags and too slow to get huge upvotes: if they're slow, they're not getting rep from the huge initial upvotes either. And "slow" is relative, because fastest-gun behavior encourages fast (and often crap) answers. People with fast, crap answers would tend towards a lower average, which is where this metric can help out. See the last point on this list.
people who answer very few questions thoroughly and get huge upvotes: if they answer questions like that, they deserve their high rep and their high average. To me, this is the ideal case. For a site premised on providing great answers, don't we want a vast majority of people to answer like that?
huge undeserved upvotes on joke questions: the undeserved rep from those upvotes would lead to an undeserved higher average. This should be an argument against awarding rep from joke answers, not against adding a rep average.
lots of answers with a few upvotes: this is precisely the behavior I'd like to see less of. A person with a very high rep score coupled with a very low rep average would suggest this sort of person, and would immediately slow down the impulse to do fastest-gun type of behavior - if someone cares so much about getting rep, they'll also care a little bit about not having a really low average.
Now, about the behaviors one would have to do in order to raise their average:
delete lower voted posts: if you care about providing good answers, you'd leave it there. If you delete them, someone else who cares about good answers will put one up anyway despite not getting rep for it. It already happens - see those who work in niche areas.
ignore low-view tags/questions: this is the niche segment case.
sock-puppet to upvote self/downvote others: there's already algorithms to detect this sort of abuse, right? those upvotes get discarded anyway.
Also, note how all these behaviors DO NOT lead to the person providing crap answers. If someone wants a really high average, they'd have to have REALLY GOOD answers. Is that a bad thing?
Now to take things completely from my side.
The way things are now, you only have the one rep metric. The rep metric is the single largest motivator that the site provides to encourage people to provide answers. If you ask 10 different users what a high metric means to them, you might get 10 different answers, but the general idea is that all 10 of those would be something positive - e.g. a high rep means the person is smart, participates a lot, provides great answers, etc. Contrast that with a low rep, which just tends towards "newbie with no privileges". This is why so many people want a high rep, and play all those rep games - there should be no question about it, rep-whoring is not desirable.
Now add rep average to the mix. Now you have 4 general cases:
low rep, low average: this could be a newbie, but if you couple that with # of answers, this could indicate a niche segment as well.
high rep, high average: this is an indicator of a quality answer, because the person in the past has gotten a lot of upvotes for their answers. The bad part is that meta-behavior may lead towards upvoting due to an already high average, but that seems to be an already-present sympton with regards to high rep.
low rep, high average: this is also an indicator of a quality answer, because their rep came from fewer answers. If the current answer isn't high quality, their rep would fall faster than an established, stable "player".
high rep, low average: the greater the difference, the more I'd distrust this answer. To me, this identifies the type of user who rep-whores a lot.