Stack Overflow does not present who voted for whom, but I wonder if it collects this data and make some intelligent deductions on it? For example, preventing a user from increasing his reputation through a fake account or a friend's account etc?

Besides fake account/voting detection, I wonder the way how smart deduction is done on any other data if there is any. For example click counts on user profiles or tags.

If there is some analytical mechanism behind, I wonder what kind of mechanism it is. Is there any rule engine or some conditions are check manually etc?

I found some articles about fake account/voting explaining the detection mechanism in an informal way like in the Anna Lear's answer. Is it possible to any find more formal explanation like is there an ontology being used or rules are hardcoded in the implementation.


I never worked on such a big project, so my question may be silly. Sorry for that.

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    As your votes are shown to yourself (and you can only vote once for each post): of course voting data is stored. – Arjan Aug 25 '11 at 18:39
  • Yeah I know it is stored, what I focused on is the reasoning methods on any data stored ;) – suat Aug 25 '11 at 19:00
  • I doubt you're going to see any formal explanation of the fraud detection algorithm. Its details are private for a reason. – Adam Lear Aug 25 '11 at 20:21
  • Yeah examples are a bit misleading as they are only about fraud detection. What I wanted to learn was technical details (not the algoritm itself) such as if there was an ontology behind or rules are directly embedded in the code, etc. I wanted learn the technique behind as Stackoverflow handles such a big data. Maybe I should have asked this as a general question in Stackoverflow – suat Aug 26 '11 at 1:44

The details of the algorithms for these aren't public to prevent exploitation, but here are a couple uses for voting stats:

  1. Moderators are notified when a suspicious voting pattern is found. They can then investigate and see if it's someone trying to boost their rep using a fake account.
  2. If someone goes out and does votes on a lot of posts by the same user in some period of time, those votes may be invalidated. Typically this happens when someone decides to exact "revenge" on a user and goes out to downvote many of their posts, but I think this mechanism tracks upvotes as well.

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