Brainmaker

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CF: user based vs Item based

  • April 3, 2014 3:14 am

http://www.ics.uci.edu/~welling/teaching/CS77Bwinter12/presentations/course_Ricci/13-Item-to-Item-Matrix-CF.pdf

  • A user profile normally contains less ratings than a product profile!
  • User-based CF – similarity between users is dynamic, pre-comupting user neighborhood can lead
    to poor predictions

    • ” Because the similarity between users can change if
      only a few ratings are changing (the overlap
      between usersʼ profiles is small)
  •  Item-based CF – similarity between items is more static
  • This enables pre-computing of item-item similarity => prediction process involves only a table lookup for
    the similarity values & computation of the weighted sum.
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