Hi, > I am even more curious why the accurracy is used as the criteria for the > second track, is the dataset a balanced one with almost the same number of > positive and negative entries (for every user)?
Yes, it is exactly the same number (3): "For each user participating in the test set, six items are listed. All these items must be songs (not albums, artist or genres). Three out of these six items have never been rated by the user, whereas the other three items were rated "highly" by the user, that is, scored 80 or higher. " Source: http://kddcup.yahoo.com/datasets.php Markus
