Does cardinality of ratings column affect performance of matrix factorization based collaborative filtering?












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I am using mllib's implicit preference based implementation of collaborative filtering for generating grocery product recommendations in e-commerce, based on this Netflix Prize winning algorithm. I tried two variations (differing in how rating is derived)-




  1. rating = no. of times user bought an item

  2. rating = (2x(no. of times user bought an item) + no. of times user viewed an item)/3 (i.e. 2:1 weights between bought and viewed criteria)


Performance (MAP, Recall and Precision) degrades from 1 to 2, which is counter-intuitive as the matrix density increases and 2nd was expected to perform better. One observation is that the cardinality (discrete values) in rating column increases in second approach and hence I want to understand if that could have resulted in the performance hit?









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    $begingroup$


    I am using mllib's implicit preference based implementation of collaborative filtering for generating grocery product recommendations in e-commerce, based on this Netflix Prize winning algorithm. I tried two variations (differing in how rating is derived)-




    1. rating = no. of times user bought an item

    2. rating = (2x(no. of times user bought an item) + no. of times user viewed an item)/3 (i.e. 2:1 weights between bought and viewed criteria)


    Performance (MAP, Recall and Precision) degrades from 1 to 2, which is counter-intuitive as the matrix density increases and 2nd was expected to perform better. One observation is that the cardinality (discrete values) in rating column increases in second approach and hence I want to understand if that could have resulted in the performance hit?









    share









    $endgroup$















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      0





      $begingroup$


      I am using mllib's implicit preference based implementation of collaborative filtering for generating grocery product recommendations in e-commerce, based on this Netflix Prize winning algorithm. I tried two variations (differing in how rating is derived)-




      1. rating = no. of times user bought an item

      2. rating = (2x(no. of times user bought an item) + no. of times user viewed an item)/3 (i.e. 2:1 weights between bought and viewed criteria)


      Performance (MAP, Recall and Precision) degrades from 1 to 2, which is counter-intuitive as the matrix density increases and 2nd was expected to perform better. One observation is that the cardinality (discrete values) in rating column increases in second approach and hence I want to understand if that could have resulted in the performance hit?









      share









      $endgroup$




      I am using mllib's implicit preference based implementation of collaborative filtering for generating grocery product recommendations in e-commerce, based on this Netflix Prize winning algorithm. I tried two variations (differing in how rating is derived)-




      1. rating = no. of times user bought an item

      2. rating = (2x(no. of times user bought an item) + no. of times user viewed an item)/3 (i.e. 2:1 weights between bought and viewed criteria)


      Performance (MAP, Recall and Precision) degrades from 1 to 2, which is counter-intuitive as the matrix density increases and 2nd was expected to perform better. One observation is that the cardinality (discrete values) in rating column increases in second approach and hence I want to understand if that could have resulted in the performance hit?







      machine-learning recommender-system matrix-factorisation





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      asked 7 mins ago









      chetna bansalchetna bansal

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