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Netflix Prize Conclusion
Yesterday, Sept 21st, Netflix announced that the winner of the $1 million Netflix Prize is "BellKor's Pragmatic Chaos(BPC)," and we congratulate them on their victory. The contest was remarkably close, and now we know precisely just how close it was.
In accordance with Netflix's rules, the RMSE score for the judged half of the submission (the test subset) is rounded to 4 decimal places. The two teams actually tied on this measurement. In this situation, the tie breaker becomes the order of the submissions. Bellkor's Pragmatic Chaos defeated us by submitting just 20 minutes earlier! Talk about close.
Netflix has graciously donated the entire data set for public consumption to: http://archive.ics.uci.edu/ml/datasets/Netflix+Prize. Included in this dataset is the quiz and test set answers, as well as the winning submission from BPC. This allowed us to determine both the precise test RMSE values and to get a little insight into the question: What would have been the result of The Ensemble and BPC working together?
Here are those values:
Test RMSE for The Ensemble: 0.856714 (10.06%)
Test RMSE for Bellkor's Pragmatic Chaos: 0.856704 (10.06%)
Test RMSE for a 50/50 blend: 0.855476 (10.19%)
The percentages are the improvement over the Test RMSE of Cinematch (.9525).
We would once again like to thank Netflix for it's pioneering contest and deft skill in managing it. It is easy to predict that Netflix Prize 2 will be just as well administered. We would also like to thank all of the numerous participants in the contest. The vast interest kept it healthy and marching forward. This little corner of science we all studied was lit up quite brightly for a while.