Back when I looked at the netflix challenge, the baseline above which improvement was barely possible was: Per person find their average rating, and score movi

Back when I looked at the netflix challenge, the baseline above which improvement was barely possible was: Per person find their average rating, and score movies not by ratings, but by how far the rating deviated from that person's average. I think that approach got me to 92% accuracy. More advanced math gave me like another 2 percent, with the winner of the challenge having gotten 96% accuracy. My point being. A very basic recommendation engine system should correct for your 4star is pretty good habit.