System design: Preventing/detecting vote fraud

Question

In light of the recent vote fraud incident here, I was wondering if anyone out there is familiar with building systems for preventing or detecting undesirable voting behavior. I imagine the technology is widely used in search engines, online advertising (e.g. click fraud), and community sites (e.g. Digg, reddit), but surprisingly little is made public for obvious reasons.

So this is my question: How would you design such a system, taking into account complexity, and user experience? Is there some domain of academic research that looks into this?

PS: This is not a question about the fraud detection mechanism or your recent personal experience here; for that please see this other question.

Answer 1

The problem is that just about any system you can create can be gamed, and good luck trying to figure out how it can be gamed before hand. Of course, the other problem is that us "Type A" personalities attach far too much weight to something that is essentially meaningless, so you get people exerting vast amounts of time and effort to maximizing their rep or minimizing somebody else's.

(And because I'm a big hypocrite but am trying not to be, I'll make this CW)

Answer 2

There is a whole lot in the literature on voting systems, and a good bit of game theory can be applied. The issue that's difficult is that it's inherently probabilistic; you pick certain patterns as indicating probable fraud, and detect or exclude them; by doing so, you also exclude the possibility that someone is voting that way for innocent, or at least non-fraudulent reasons.

Consider, eg, someone who reads my deathless prose, develops an instant man-crush on me, and goes through all my answers voting each one up. I've got more than 30 answers so it would take a few days. Now, by assumption, this isn't my reputation-whoring sock-puppet, it's a person who for their own reasons, however unwise, has devoting all their voting to me for days at a time.

Is this fraud? No, but it would be detected as, and probably treated as, fraud.