Item-based top-N recommendation algorithms

Mukund Deshpande, George Karypis

Research output: Contribution to journalArticlepeer-review

1709 Scopus citations


The explosive growth of the world-wide-web and the emergence of e-commeroe has led to the development of recommender systems - a personalized information filtering technology used to identify a set of items that will be of interest to a certain user. User-based collaborative altering is the most successful technology for building recommender systems to date and is extensively used in many commercial recommender systems. Unfortunately, the computational complexity of these methods grows linearly with the number of customers, which in typical commercial applications can be several millions. To address these scalability concerns model-based recommendation techniques have been developed. These techniques analyze the user-item matrix to discover relations between the different items and use these relations to compute the list of recommendations. In this article, we present one such class of model-based recommendation algorithms that first determines the similarities between the various items and then uses them to identify the set of items to be recommended. The key steps in this class of algorithms are (i) the method used to compute the similarity between the items, and (ii) the method used to combine these similarities in order to compute the similarity between a basket of items and a candidate recommender item. Our experimental evaluation on eight real datasets shows that these item-based algorithms are up to two orders of magnitude faster than the traditional user-neighborhood based recommender systems and provide recommendations with comparable or better quality.

Original languageEnglish (US)
Pages (from-to)143-177
Number of pages35
JournalACM Transactions on Information Systems
Issue number1
StatePublished - Jan 2004


  • E-commerce
  • Predicting user behavior
  • World wide web


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