July 8th, 2009


Netflix Recommender Prize Won (probably)

Netflix has posted a contest for improving its own movie recommendation system by at least 10% and the prize is a million dollars. People have been working on this since 2006, and there have been several Progress prizes. Finally, four teams merged to create the BellKor's Pragmatic Chaos Team, which added temporal dynamics to the recommendation weights. This beat the current Netflix recommendation algorithm by 10.0%%.

A press release from the 15th ACM SIGKDD (Conference on Knowledge Discovery and Data Mining) explains, 'While movies themselves stay the same, the humans who rate them are anything but static. As [Yehuda] Koren puts it, "The way I rate movies today can be very different from how I rate them even tomorrow."'

However, as per the rules and a note in the Netflix prize forum that under the terms of the contest, the other teams have thirty days, until July 26, 2009 to submit their own solutions, and be considered for the prize. That makes sense, because the others may have been refining algorithms and testing slowly.