Give an incentive for finding duplicate questions

I'm reviving this thread because I'm surprised there's no badge offered for this. Looking for duplicates requires more effort than other types of close vote and we're always saying that badges should be encouraging positive behaviour on the sites.

I propose the following badges:

Seeker - First question closed as a duplicate of another question you found.

Scout - 50 questions closed as a duplicate of another question you found.

Reconnoiterer - 200 questions closed as a duplicate of another question you found.

The underlying criteria would require at least 3 of the total close votes to concur with the found duplicate. Reconnoiterer could possibly be a repeatable to encourage continued behaviour. I can't see any "gaming" issues arising from this, because it requires agreement from other members of the community.

Clarification: "found" equates to finding a duplicate and casting a vote to close on that duplicate, or flagged for review with the appropriate duplicate chosen.

One way to incentivize finding duplicate questions would be to make it easier to find them. A tab could be added to the review section for "Possible Duplicates".

When you type in the title for a new question, you see "Questions that may already have your answer". The functionality that creates that list could be adapted.

New questions that meet a certain threshold of commonality with existing questions could be shown along with the list of "Questions that may already have your answer" that met the threshold.

The trick is to find a system that only rewards work. My proposal:

• When (say) 5 people have identified a question x as a duplicate of question y, award rep to those 5 people and close the question.
• Don't reveal which questions have been suggested as duplicates before a question is closed.

The 2nd point is important to avoid triggering a close-as-dupe epidemic. It means that people individually have to do the work (searching for dupes) to get the rep. You have to be fast (otherwise 5 other people will get there first), and you have to be right (pick the dupe that others picked).

Inspired by: The ESP Game from Games With A Purpose (from about 22:30 onwards, though it's all fascinating stuff!)

Thoughts? Are there ways that this system could be abused?

UPDATE 2/5/2012: Eliminating Cheating

Jeff's comment raises a valid concern that people could easily game this system by voting to close a question as a dupe and then writing a comment mentioning the other dupe; others will then vote to close as the same question. I can see this happening because there's positive feedback at work here -- both the original comment-writer and subsequent close-voters stand to make some quick rep. But I think I now have a solution to that:

To prevent people "dropping hints" about dupe-parents in comments/answers, you could simply forbid people from both identifying a question as a dupe and commenting on or answering that same question -- i.e. as soon as you do one, you can't do the other(s).

Think about it: if you see a question and immediately recognise it as a dupe of something else, there's no need to comment on/answer it. The only scenario I can think of where this might be too hard-line is when someone uses a comment to ask for clarification, and only recognises the question as a dupe after receiving that clarification, but this would be pretty rare. In the unlikely event that this turned out to be a common problem, the system could just be changed to waive the restriction for users above $SOME_THRESHOLD_REP.

I am all for rewarding closevotes (not only finding duplicates). If reputation

is a rough measurement of how much the community trusts you; it is earned by convincing your peers that you know what you’re talking about.

it is illogical that only answering increases reputation but closevoting doesnt. If I supply a closevote and people follow it, I have effectively convinced them that I know what I am talking about, too - namely that a particular question should rather be closed than answered.

Moreover, even if a question is closed, it will usually have received some answers before. The reputation gained on these remains unless the question is deleted. Deletion rarely happens due to the 20k requirement. But if it remains it implies they gained trust, while those that closevoted dont gain anything at all, although they did the right thing and those that answered did the discouraged thing.

So if reputation really is a measure of community trust, closevoting should gain reputation as well. This is true for all the additional privileges gained. If we want more people to use them, we have to reward them for it. Currently, the only reason why a 3k+ user would closevote is because s/he understands the necessity of it. Unfortunately, there is even a lot of high rep users who dont see that and repwhore on whatever they can answer. Are those really the people we trust?

Regarding the problem of incorrect closing I am quite sure that this is only a minor issue. I've seen far more correctly closed questions than reopened ones. The few false positives could be further mitigated by allowing to uv/dv on the votes instead, e.g. cast a closevote and have people vote it up or down until a threshold is reached. +5 will close, -5 will fade the vote. And allow people to revoke their vote please.

Regarding rewarding and badges, I dont see why we cannot have both. Someone who continuely does her/his community duty and closevotes should be rewarded for it with a badge or two. Badges are not enough to encourage closevoting though, because once you got the badges, you dont have an incentive to closevote anymore. So we also need some reputation gain.

I know its tiresome to see duplicate questions but I am guilty of this as it is sometimes hard to find the duplicate in the sea of questions. I wanted to ask a question about deleting my own posted question, I did a search for this and came up with 50 pages of questions with the same search parameters. I looked at the first few pages...but this got me thinking that sometimes users post duplicates because they need the answer but don't want to search through the sea of questions as this would take more time than posting a question. I like the idea of rewarding the finding of a duplicate to the first person who finds it then it gets put up to vote and if enough votes agree then it gets merged into the old question answer.

You might be interested in my script Duplicate Question Suggestion Boxes which makes this more easy.

An example of its effectiveness, where otherwise the link would be hidden somewhere in the side bar:

Of course, we can't enable this for all users.

Maybe you could add "flag as possible duplicate" as a top-level option in the flag-moderator box? (with a requirement for a link).

That makes it more obvious promoting it happening more, and opens it up to lower-rep people to flag as possible duplicate, without directly voting for duplicate.

This is a terrible idea. There, let me be the first to put in a negative answer.

I have had to reopen some questions because not all SOpedians are as smart as the next bloke. They see some similar words, and think it must be a duplicate.

There also seems to be some moths that are driven to brackets around Close(n) and see their call of civic duty to blindly follow where others have gone before.

Similar to my advocating against this: Should the sportsmanship badge be awarded multiple times?, I'd like some hard numbers for % of questions actually closed as duplicates.

Let's say theoretically

0.1% closed as duplicates
0.12% failed attempts to close
0.016% reopened
no badges

I reckon you will see the close/reopen buckets both increase significantly (more towards close since it is incentive-ised) and failed attempts go through. My reasoning is simple - human nature. Just as people will cast votes for opposing answers for a week and never again for sportsmanship and vote solidly for another 17 days^* after for electorate (and also thereafter rarely vote again).

^*If you don't believe me, just go to http://stackoverflow.com/users?tab=voters They stick out like a sore thumb with votes an exact multiple of 30.
_{Disclosure: I'm guilty too, but I actually continue voting as much because I do really read that many questions!}

For new users, few questions are duplicate. Both new answerers and new askers get frustrated when they are trying to do the right thing, but it gets closed as a duplicate. Their initial reaction is not: "Thanks for pointing me to the right question", but: "Why are you rudely interrupting my conversation?"

The irony is that the old users enjoyed the very same thing they are denying to the new users. With the very same questions, and the very same answers: the only difference is the timestamp on the question.

Even more irony is that most high-reputation users got high reputation by answering questions instantly. The fact that they can answer instantly is a strong indicator that the question has been asked before, and is on the top of their tongue. In other words: most high reputation users are very good at answering duplicates.

At the end of the day, the fact that only a small number of duplicates gets closed means its not a big problem. But until duplicates are closed in a socially acceptable way, I think it would be a very bad idea to reward or even encourage more duplicate closes.

The key to any community-based, "Duplicate Task Force" is opening and simplifying the process.

First, provide 1k+ rep users with a "flag as duplicate" option, which will allow for a single link to be provided. This makes it easy and painless to report.

Display the flag and the duplicates found to the asker (and others? Debatable.). This makes the process open, and will help the asker.

Then, facilitate moderators' (or 10k+ rep users') job by providing them with a list of duplicate-flagged questions. Allow sorting by number of duplicates found. This makes the process manageable.

Finally, provide the users who flagged the question with one duplicate or another (it's not a game to get the right one) with a small incentive. Lock down rewarding after question has been closed as duplicate. That makes finding duplicates rewarding.

We should just give a badge for 'Closing as Duplicate' enough times (when it's the confirmed close reason). I do not want to disincentivize good answers even to duplicate questions. All questions deserve good answers.

I think this is a great idea. Especially the "duplicate finder" badge. It has been argued that this may require a feature to mark duplicates, but that may not be needed. Anyone who has sufficient privileges to add comments can add the link to the duplicate in a comment. If the question is closed, the Stack Overflow engine can harvest the URL, and award a badge to the user who was the first to link the question with the duplicate, albeit through a comment, or through a close vote.

Some of the other answers argue that questions are closed as duplicates, where the question is not actually a duplicate. This is true. And this may happen more often if duplicate finding is encouraged.

But this is not a problem.

If the person asking the question disagrees, she can always compose a better documented question, referring to the other questions, and point out why her question is not a duplicate. I don't expect this to happen more than a few times in every hundred duplicates, so we should not worry that this will flood the site with more duplicates.

I'd also like to see the removal of reputation earned from answering a question that is later closed as a duplicate. Currently there is little incentive to post an answer on the original question (or merely post a link to the original), rather than re-answering the question. It's tiresome seeing the same answers again and again, and seeing this behaviour awarded with reputation.

We could implement this in much the same way as the vote to close system. A user could submit an "answer" that is somehow marking this question as a duplicate and all other users could see it, and respectively vote if it really is a duplicate. 5 votes closes the question, and maybe gives -5 rep to the asker (seems fair to me if they can't search).

Send us a package of cookies for every 100 duplicates we vote as duplicate.

No rep gaming issues, no badge gaming issues, no problem!

Another possible solution might be to separate the problems of flagging duplicates and voting to close the duplicates. What if anyone (or almost anyone) could flag a duplicate using the functionality presently built into "close as duplicate?" Then "close as duplicate" would be enabled for higher reputation users once the first duplicate has been flagged.

Not sure this is a great idea. On the surface it sounds interesting, but often times people simply skim the question and then vote to close not realizing that there are differences in the questions. It then is much harder to get the question reopened and basically an uphill battle.

I'm wondering if it doesn't make sense to lower the reputation threshold to vote to close as a duplicate. Unlike other votes to close, there is already a bit of a check on this; you have to actually point out which question this is a duplicate of. That discourages (at least a little) people from doing it casually. So unlike "subjective and argumentative," where it's really a matter of opinion, and makes sense to restrict to higher reputation users, it would be good to have more participants in fighting duplicate questions.

Regarding your second point, the site already marks questions as possible duplicates after a certain number of votes. Perhaps it could do so (less intrusively, maybe) after the first vote?