Dealing with answers in comments.

Question

I have noticed, of late, people providing answers/copious hints to the question in comments instead of actually adding an answer on their own.

Other people might choose not to answer, as the question has already been answered, and it might offend the person who commented with the answer. In time, this will lead to the site having a lot of questions with 0 answers which actually have an answer in the comments.

Some possible consequences of having answers in comments:

1) Potentially waste time of people. Personally speaking, I read the question before reading the comments, and so I have just wasted a few minutes when I possibly didn't have to. Some people might choose to answer it straight away and find that they have just repeated someone's comment in an answer.

2) The question goes to the unanswered list and they are bumped up periodically by the Community user.

3) Comments are not indexed by the full text search. So we have valuable content just lying around in dead questions.

Here are a couple of examples:

If $f$ continuous and $f(x^2) = f(x)$, then $f$ is a const. This one has an incorrect answer, while the correct answer is in a comment.. The commenter was kind enough to add a detailed answer, upon request.

Connectedness of sets in the plane with rational coordinates and at least one irrational

This problem seems to be more severe with homework like questions. If one is worried about earning trivial rep, one call always add an answer and mark it CW.

So, in case someone adds an answer in comments, what should one do (while not hurting any feelings perhaps)? (Ignore is not an option :-))

I wanted to open this, so we could direct any future comment-answerers to what the community opinion is regarding this (if any).

Note: I am not suggesting we have a policy/faq entry. This question would serve that purpose, if possible.

Answer 1

I think one should first leave a comment asking the user to post their comment as an answer, explaining that this will allow the question to be marked as answered. This often works, and it may encourage the user to post full answers in the future.

If the commenter won't do so, I agree that one should go ahead and post the comment as a community wiki answer. (As of writing, 10 other people agree that this is a good idea, going by the votes on this previous question).

On the other hand, if one wants to add further information and not merely duplicate the content of someone else's comment, there is nothing wrong with posting that as one's own (i.e. not CW) answer. If one is concerned about hurting feelings, one can acknowledge in the beginning that this answer is an elaboration of the answer given by the other user in the comments.

Answer 2

If you answer a few questions that get closed, you get a note from the Moderation Team, telling you to stop doing that. If you answer a few more questions that get closed, you get suspended. If, instead, you write answers in comments, nothing happens to you.

"Well," you say, "you shouldn't be answering questions that are going to get closed." OK, but some questions are borderline, it's hard to tell whether they'll get closed or whether they'll survive. Some questions, after they get closed, the community reconsiders, and decides they shouldn't have been closed, and they get re-opened. It's not always easy to tell whether or not a question meets community standards.

And some questions get closed as duplicates. With $4,000,000$ questions on site, there are a lot of places for a duplicate to hide, and even those of us who know some of the tricks for finding them are going to miss them sometimes. And, again, sometimes questions get closed as duplicates by mistake, and the community votes to re-open, so even duplication isn't always easy to decide.

All in all, if you have any doubt, it's safer to answer the question in a comment than in an answer.

Well, somebody had to say it.

Answer 3

I actually wanted to post the same question since this issue has been bothering me for a long time, but I found this post (and lots of duplicates), so let me just add my 2 cents here.

I think we have a huge problem with people writing answers in comments, and it happens all the time, both on MSE and on MO.

Several (bad) reasons for writing answers in comments

In many cases, a question can be answered with one or two sentences. In these cases, some people prefer to write their answer in the comment section, because they assume that an answer has to be longer, including lots of details, references, proofs. This assumption is not correct, of course. An answer should be posted as an answer, regardless of its length. When the OP needs further assistance, the answer can be expanded later on.

Sometimes these answers in comments are just small hints that are supposed to help the OP to find an answer on their own. However, I have seen again and again that these hints are actually just "quick thoughts" which might eventually be misleading and not helpful. Here, the commenter did not take enough time to write a full answer and hence (ab)used the commenct section for this piece of (sometimes bad) advice. In these situations the comment section might evolve into a full discussion, including several further questions by the OP. This goes against the fact that MSE is not a discussion forum, it is a question-answer site.

I also observe that many commenters prefer to write an answer in a comment because they think that the question is trivial. They don't want to be bothered to write a full answer which actually helps the OP. They ignore that, what is trivial for them, might not be trivial, actually very hard to understand for the OP.

It also happens quite often that answers are written in comments when the question is likely to get closed, for example because it is a duplicate or of bad quality (or too trivial, as in the previous paragraph). In these cases, there is a general recommendation to not write answers. But it seems that many people don't understand that this recommendation of course also applies to answers written in the comment section.

What we can do?

In case the comment contains a proper answer, I often ask the commenter to post their answer as an answer then. It does not always happen, though. Sometimes, in particular when I have asked the question myself, I then write a CW answer myself, copying the comment into it, so that I can mark the question visibly as answered.

Personally, I think that we need to have a better solution here. For the start, it would be good to have a reference (EDIT: the Help Center and Meta/19756 already provides such a reference) where it is explained clearly that and why answers should not be written inside of comments. Maybe accompanied with a teaser text that links to this reference. Then we might be able to copy paste this text.

Let me start something that may be copied (edits are welcome!):

This is an answer to the question, not just a comment. Comments should only be used to clarify, not answer the question. See How do comments work for more information. Therefore, please post your answer as an answer. This brings extra visibility to the answer und puts the question off the unanswered list. Also notice that comments are not indexed by the full text search, don't have any revision history, can only be edited for 5 minutes and allow only limited markup.

But in the long run, this will not change much, since there are a lot of poeple who are new to the site and just do not know this recommendation. To new users, there should be a popup before they are submitting a comment. Alternatively, there should be a flag option for comments, saying that it is actually an answer.

Update: I have copied this message now under several "answers in comments"-type comments (of which I see about 10 per day). Not sure if it helps, let's see. Example.

Answer 4

I find answering in the comments to be annoying, to the point where I have reported the answer-comments to moderation, and gotten many of these answer-comments deleted. The thing is, answering in the comments completely changes the way MSE works.

To the best of my knowledge going by the Help Section, this is how MSE is supposed to work. Someone asks a high-quality question--one that is thought-provoking and interesting to a wider community, not just to the person asking. Then someone else thinks about it and comes up with a clearly expressed answer to that question. The person who answers the question is rewarded not only with a sense of accomplishment--and an uprated skillset for figuring out a solution to the question, but also upvotes which translates to an increasing set of voting privileges for that user on this site. The site meanwhile benefits from this in that it becomes a repository of interesting questions with well-written answers. Sounds great to me. I mean, it isn't perfect--as pointed out by Gerry Myerson above, it isn't perfectly clear what counts as a duplicate or not--but overall it is a sound model I think.

However, answering in the comments, throws a wrench into all this. There is no more rep or satisfaction to be gained from answering a question and writing it up nicely for posterity, as someone likely already presented the crux of the answer in the comments. I say it kind of takes the fun away from participating, and that can't be good for the site. [There is a reason why "rep" was put in for answering the questions when the Stackexchange sites were built--as silly as it sounds on some level. It does have consequences such as voting privileges which affects how MSE is run. Also, there isn't anyone who uses the Stackexchanges for networking purposes?] Also, as a result of all this hinting or answering in the comments, low-quality questions are getting rewarded with an online tutoring session on here, which means....more low-quality questions. That can't be good for the site either.

Anyway, I already can see the backlash from those who say that my views are elitist, that MSE should really be an online office-hours where the goal should be the student answering his own question--[and comment-hints and comment-answers are as the thinking goes, the best way to do this and help the student]. I actually don't agree with this at all. For one thing there is no doubt a lot of students will use this site in a way their professors did not intend to, to try to get an unfair advantage on their fellow students. The joy of helping someone, for me, is also tinged with a 'wait did I just help someone on their take-home exam'. For another, I believe one should get rep by answering questions that are of interest to the wider community e.g., answering questions asked by someone else for one thing, instead of by themselves. Why should you get points on here for doing your own homework?

My 2 cents.