The University of Minnesota has been doing work with collaborative recommenders for more than a decade now. Their original project, GroupLens, was a system for using collaborative filters for recommending Usenet messages.

In 1997, Compaq shut down their own collaborative movie recommender ("EachMovie") and made the datasets available to public researchers. MovieLens piggybacked on the original interface (lists of ten movies with a drop-down allowing you to rate the movie from 0 to 5 stars), but has since added many features.

The database of movies on MovieLens is not comprehensive but new movies are added pretty regularly, and the database administrators are very responsive. The recommender frequently made recommendations using half-stars and users are now allowed to rate movies in half-stars now. You can create a wishlist, and you can also form "buddy" relationships with other users and get joint recommendations. Finally, MovieLens allows users to see how many votes have been collected for a particular movie, and whether the prediction made for the user differs from the average vote.

MovieLens is an academic tool, and users are frequently asked to participate in research projects. Recent experiments have looked at the relationship between message board activity and likemindedness, or have paired up users to participate in a "Family Feud"-like trivia contest. Many of the papers that have resulted from these experiments are posted at the GroupLens site. GroupLens also makes datasets available to other researchers.

The recommendation lists generated by MovieLens seem to be mostly based on the predicted score, without much concern for "confidence." As a result, the list seems fairly volatile and the top recommendations are often for relatively obscure movies. In this sense, I consider the recommender to be "daring." I generally use MovieLens' list of All Movies for All Genres to inform my video rentals. Recently, the recommender suggests I pursue the documentary Cinemania, about New York City film geeks. I use the Wishlist to keep track of movies playing locally, in case I ever get to see a movie again. Starsky and Hutch was this week's recommendation. As always, maybe these things should be taken with a grain of salt, though I will also point out that the student-run art theater is closed for spring break.

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