And, in fact, modeling these biases turned out to be fairly important: in their paper describing their final solution to the Netflix Prize, Bell and Koren write that Of the numerous new algorithmic contributions, I would like to highlight one – those humble baseline predictors (or biases), which capture main effects in the data. While the literature mostly concentrates on the more sophisticated algorithmic aspects, we have learned that an accurate treatment of main effects is probably at least as signficant as coming up with modeling breakthroughs.

Winning the Netflix Prize: A Summary - Edwin Chen's Blog Saturday, April 26, 2014 @ 4:56pm