(Note: my earlier comment was nonsense, based on a misreading of what Richard wrote.) That does seem to be what Phil says, but in the the scheme I have in my head after reading Phil's proposal, things go a little differently. For the avoidance of doubt, I am claiming neither that Phil would want this nor that it's the right thing to do. * Suppose A votes on something B wrote. They have some history: A has voted +1, 0, -1 on u,v,w of B's things in the past. Here u+v+w is the total number of things B's ever written. * I think we probably want to ignore the ones A hasn't voted on. So we care only about u and w. * What should our prediction be? One simple answer: we assign probabilities proportional to u+1,w+1 to votes +1,-1 on A's next vote. (This is basically Laplace's rule of succession, or equivalently it's what we get if we suppose A's votes are independently random with unknown fixed probabilities and start with a flat prior on those probabilities.) * We might actually want to start with a different prior on the probabilities, which would mean offsetting u and w by different amounts. * Now along comes A's vote, which is (let's call it) a, which is either +1 or -1. The score it produces is - a log(Pr(A votes a | history)); that is, - log (u+1)/(u+w+2) if A votes +1, and + log (w+1)/(u+w+2) if A votes -1. This is added to the score for whatever it is B wrote, and to B's overall total score. With this scheme, an upvote always has positive effect and a downvote always has negative effect, but as you make the same vote over and over again it is less and less effective. For instance, suppose A upvotes everything B posts. Then A's first upvote counts for -log(1/2); the next for -log(2/3); the next for -log(3/4); etc. The total effect of n upvotes (and nothing else) is to contribute log n to B's score. There are some things about this that feel a little unsatisfactory. I will mention three. First: although "vote counts for plus or minus number of bits of info

That seems pretty reasonable to me. [EDITED to add: except that what I was saying "seems pretty reasonable" was not in fact what Richard wrote; I misread. See comments below.]