> a user who gives everyone a 2 but occasionally gives their best friend a 5 will wind up having that "5" normalized to some astronomically great rating You ca

> a user who gives everyone a 2 but occasionally gives their best friend a 5 will wind up having that "5" normalized to some astronomically great rating You can just cap the max-value at a 5, to avoid someone getting a "astronomically great rating". Rating normalization isn't meant to prevent rating-fraud, nor does it make the problem significantly better/worse than it currently is. But it will solve the problem of rating inflation. Not to mention that once users know that their ratings are being normalized anyway, they won't feel the need to give everyone a 5-star rating.