I recently had a interesting discussion with a user regarding his particular heatsinking issues attached to an answer I gave here.

However, since then, Kortuk♦ has come by and stated:

@FakeName Can you message me when you add applicable information to your post and I can clear these comments? Otherwise I will just purge in a day or two.

Now, I understand (if not agree with) the desire to clear out comments that are clearly unconstructive. However, in this case, the comments were clearly illustrative of the process of choosing the appropriate heat-sink solution, while beeing somewhat too localized to be part of the answer itself.

I cannot see any good reason to delete these comments. They're both informative and amicable. I think that the knee-jerk deletion of any comment threads longer then ~5 comments is an absolute anathema to a proper educational, open discussion.

Frankly, the process of designing things is as or more crucial then the parts involved, and it is very difficult to illustrate the process without at least some back and forth. If you want to claim that trying to illustrate the process of designing something, particularly in the context of walking someone through the design process is not a good fit to the SE format, that's fine. Then close the question.

Otherwise, the deletion of useful, informative comment discussions is absolutely toxic, and should be discouraged.

• From this I find your use of "knee-jerk" out of place. That implies I came through and at a whim just deleted things. I came and found a very long comment chain with what looked like applicable information hidden in it, I then asked if you would merge it into your answer so that your answer could be more thorough. I realize this is a point of contention for you, I am not arguing that part here, but I am not sure how the use of "knee-jerk" is applicable. – Kortuk Oct 22 '12 at 11:13
• – Kortuk Oct 25 '12 at 14:03

The "knee-jerk" reaction of having too many comments comes in around 20 comments - or about a page and a half of comments. To put this in perspective, your answer was only a page with judicious use of (much appreciated) formatting. I think it's fair to say that the comment thread was getting long. So when you're done with helping the OP, we would like to clear out the comments (or at least thin them down significantly).

I would like to note that I find your statements conflicting. Where you say the comments are "somewhat too localized to be part of the answer itself" you then go and say that the comments are "both informative and amicable" and I tend to agree with the latter statement.

In this comment thread, you and the OP have uncovered information that should have been present in the original question (Package type, PCB layout) and as a result you have given information needed to bring the answer full-circle to the part where he's wondering why his solder is melting. The problem is that you have to read a page and a half of discussion to get to that point. This information should be in your answer, and it would then be in an easy-to-understand format as part of a logical answer. Ideally, this answer could be used by many people down the line with similar issues.

There are two problems that the long comment threads cause. The first is that fundamentally StackExchange is a Question and Answer site - these are what can have value (reputation). The question should be a complete stand-alone question, and each answer should be a stand-alone answer. Comments have no "staying power" so they shouldn't be used to "store" useful information - that's what the answer box is for. This is really a "StackExchange Philosophy (TM)" that we as mods are trying to "enforce".

Second, it gives a bad user experience for a user trying to understand what's going on. You would need to read through a page of technical talk before you found out that the PCB was inadequate and that the datasheet was misunderstood. Put it in your answer in an organized way, and all the context for those statements will be there, and the question and answer will make sense as a whole.

As a result, if you believe that all the material in the comments truly is "too localized to be part of the answer itself" then you should have no issue with the comments being cleared out because they won't help anyone else. If you transfer the relevant information from the comments to your answer, then you should have no issue with the comments being cleared out. And if you decide to not incorporate the comments into your answer, we will take that to mean that you think the information is not worth saving.

• The conflict comes from the fact that there are two core things most answers illustrate. The general rules for (in this case) choosing a heatsink, and the process I used in this specific case for doing ball-park estimates. In this context, the former is largely covered by the answer, and the latter is what I walked the questioner through in the comments. – Connor Wolf Oct 22 '12 at 5:49
• And if you decide to not incorporate the comments into your answer, we will take that to mean that you think the information is not worth saving. I did think the information was worth saving. That's why I wrote it down (in this case in a comment). – Connor Wolf Oct 22 '12 at 5:49
• Is there some general decree that comments cannot contain useful information? That makes no sense. – Connor Wolf Oct 22 '12 at 5:50
• When I answer a question, I tend to focus on the theory and generalities in the answer, and if needed pursue Questioner-specific things in a discussion in the comments. This way, people who want an overview can just read the answer, and if someone want's to try to understand the application of the methodology, they can expand the comments. – Connor Wolf Oct 22 '12 at 5:52
• It's possible I'm using the SE platform "incorrectly", but this system seemed to work fine, until the recent aggressive comment-pruning that seems to be a new thing. – Connor Wolf Oct 22 '12 at 5:53
• I guess it comes down to what you focus on. I tend to think that demonstrating how you go about solving a problem, including what information you focus on to make that decision, is absolutely invaluable for people who are learning. It is very hard to present such a demonstration as a monologue. I think the back and forth of the comments themselves much more effectively illustrate the process, which is far more critical then the answer itself. It shows how to learn, rather then what you should learn. – Connor Wolf Oct 22 '12 at 5:56
• Furthermore, the OP actually asked a number of further, related questions in the comments. While they would be useful as stand-alone questions, they're quite relevant to the question at hand. With regard to incorporating them into my answer, it would effectively turn my answer into a complete thread, which seems a bit silly. However, having the information proximate to the original question (which they are logical extensions of) makes the most sense to me. – Connor Wolf Oct 22 '12 at 5:59
• On the whole, while I admit that the comment threads are not an ideal medium for storing such discussions, there are not any better places to put a lot of the things that go on in them, and most of them cannot be easily edited back into the question or answer. I think the removal of the comment threads does a great disservice to this site, and would (at least for me) strongly discourage me from commenting. – Connor Wolf Oct 22 '12 at 6:00
• I mean, why comment if it might get deleted before the other person even sees it. – Connor Wolf Oct 22 '12 at 6:00
• Comments are basically "second-class citizens" on StackExchange. They have no revision history, and when they get deleted, they're gone for good. In contrast, answers and questions have detailed revision history as well as being preserved even if they are "deleted". We would like anything that can be considered "valuable" to live in answers and questions instead of just in the comments. – W5VO Oct 22 '12 at 15:25
• The goal is for you to include the salient details of your discussion with OP into your answer, where someone else would be able to use it. I think you are exaggerating how difficult it would be for you to incorporate your information in the comments into your answer. – W5VO Oct 22 '12 at 15:38
• And so the point of comments is communication. We aren't trying to interrupt that purpose, but as far as we (the mods) can tell the conversation is over, all parties have read the comments, and it has served its purpose. This isn't automatic, this isn't "knee-jerk", this is (in our opinion) the appropriate response for this situation. – W5VO Oct 22 '12 at 15:50

On the whole, while I admit that the comment threads are not an ideal medium for storing such discussions, there are not any better places to put a lot of the things that go on in them

Untrue. A much better place for extended discussions is in a chat room. Which is why, when there is a lot of back and forth, the site recommends moving the discussion to chat.

For example, a user had a question about an ADC in this question: Analog to digital conversion

Some back and forth occurred in the comments where the user was having trouble implementing the formulas and printing out the answer in code. The discussion got a bit long and the site asked us to move it to chat. So we did. Now, at the bottom of the comments, there is a link to the extended discussion that happened in the chat room:

Our discussion lead to the user asking another question about how to print floating point numbers: Formula calculation and printing negative value.

In my answer to that question, I reference the chat room for anyone who might find the discussion of how we arrived at the answer useful. All of the relevant information, I copied into my answer.

I believe that this is proper use of the Stack Exchange system by following the Q&A format but including a hyperlink to an extended discussion on how an answer was reached for those that are interested.

This room should exist forever so that the relevent information is not lost according to the chat FAQ:

Rooms will exist indefinitely, so long as there is at least one person actively talking in the room. A room is considered worth retaining if it has more than 15 messages by at least 2 users.

Rooms not worth retaining which are inactive for 7 days will be deleted. Rooms worth retaining which are inactive for 14 days will be frozen. Frozen rooms do not allow any new messages to be sent, and are not shown in the default room list to prevent cluttering the rooms interface.

• While chat is a nice idea, very few people use it! (particularly new users) As such, it really isn't an effective medium. I've tried multiple times to move long comment chains to chat, and it usually doesn't work. – Connor Wolf Oct 22 '12 at 20:51
• @FakeName I've only had the site ask me to move to chat twice. Both times it was in a discussion with new users. And both times, we moved to chat and the discussion went great. Guess I've just been lucky in my experience. I personally find the chat rooms to be a great medium for exactly the problem you describe. – embedded.kyle Oct 22 '12 at 21:08
• I would add that bringing over useful information from that chat is also a good idea. Have your answer expand into what you found was also needed from your chat conversation. – Kortuk Oct 23 '12 at 13:26

Discussions have a poor signal to noise ratio. Filter out the noise, compress out any redundancy in the signal, copy the important content into your answer (or question), and then delete the discussion. That way visitors can get the important information immediately without having to wade through pages of discussion. This is why wikis > forums.

That said, comments shouldn't be deleted before the information is folded into the answer...

• Yes Yes Yes! Exactly it and very concise. It may seem to some that you loose seeing the back and forth, but to someone wanting an answer that back and forth is rarely if ever wanted. There is just so much noise they are going to go somewhere else. If I search something I would open 5 tabs of possible answers and then the moment one seemed to be noise/incorrect I just closed the tab and move on, no second thoughts. – Kortuk Oct 25 '12 at 14:00
• Yeah, I read thru the comment chain now that Kortuk posted a link to them, and there is a lot of noise in there. There is also some useful information, which could easily be refined and added to the answer using a lot fewer words than the whole pile of comments. – Olin Lathrop Oct 25 '12 at 15:27