How does Stack Overflow determine sock puppet accounts that give "fake" upvotes to questions?
I am specifically interested in the statistical approach Stack Overflow takes (IP addresses or user-agents need not be part of the answer). It's okay if propriety details are not revealed. But we can still benefit from knowing the general approach Stack Overflow takes.
My gut feel is that Stack Overflow uses a record of each user's voting decisions (e.g. last 50 votes cast by the user). They use this historical data to calculate whether a vote currently being cast can be flagged as a socket-puppet or not (i.e. it's above some Bayesian probability threshold). And when enough sock-puppet votes materialize, Stack Overflow takes action against the profiles involved.
Could an expert shed light on how Stack Overflow does it?