I loved your overview of the Netflix prize competition. Napolean Dynamite is a great example of how recommender systems “get confused”. One day I may try something for the netflix prize, but it takes time, and I don’t have much of that.

Netflix is really a pioneer in the recommendation arena. They have their competition to improve their algorithm which has received a lot of attention. I am not sure how I forgot about them.

I haven’t looked at Amazon recommendations recently so I don’t know if the format has changed, but it strikes me that one of the problems with their recommendation feature was one of categorization. Novels were interwoven with children’s books and web design books. It would have been far more useful if I can have gone done the branch I was interested in (or even suppressed a whole category).

NetFlix has had far better results with its recommendation system at least as far as I am concerned. It had the feature of showing people with similar lists with you and giving the percentage of overlap. You could then go look at that person’s list and see what else they had on the list that might be of interest.

I think the one limitation of Netflix’s viewer matching system was a failure to weight it in any way. My guess would be that the fact that I shared an interest with the someone in a highly popular film like “Star Wars” or “Big” is of less significance than the fact that we shared an interest in an unusual film like “Saragosso Manuscript” or “The Visitor”.