Using external aggregate ratings for improving individual recommendations

Akhmed Umyarov, Alexander Tuzhilin

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


This article describes an approach for incorporating externally specified aggregate ratings information into certain types of recommender systems, including two types of collaborating filtering and a hierarchical linear regression model. First, we present a framework for incorporating aggregate rating information and apply this framework to the aforementioned individual rating models. Then we formally show that this additional aggregate rating information provides more accurate recommendations of individual items to individual users. Further, we experimentally confirm this theoretical finding by demonstrating on several datasets that the aggregate rating information indeed leads to better predictions of unknown ratings. We also propose scalable methods for incorporating this aggregate information and test our approaches on large datasets. Finally, we demonstrate that the aggregate rating information can also be used as a solution to the cold start problem of recommender systems.

Original languageEnglish (US)
Article number3
JournalACM Transactions on the Web
Issue number1
StatePublished - Feb 1 2011


  • Aggregate ratings
  • Cold-start problem
  • Collaborative filtering
  • Hierarchical linearmodels
  • Predictive models
  • Recommender systems


Dive into the research topics of 'Using external aggregate ratings for improving individual recommendations'. Together they form a unique fingerprint.

Cite this