Eigenvalue Perturbation for Item-based Recommender Systems

Adding confidence estimates to predicted ratings has been shown to positively influence the quality of the recommendations provided by a recommender system. While confidence over single point predictions of ratings and preferences has been widely studied in literature, limited effort has been put in exploring the benefits provided by user-level confidence indices. In this work we exploit a recently introduced user-level confidence index, called eigenvalue confidence index, in order to provide maximum confidence recommendations for item-based recommender systems. We firstly derive a closed form solution to calculate the index, then we propose a new recommendation methodology for item-based models, called eigenvalue perturbation, founded on the strongly positive correlation between the index value and the accuracy of the recommendations. We show and discuss the accuracy results obtained with a comprehensive set of experiments over several datasets and using different item-based models, empirically proving that applying the new technique we are able to outperform the original recommendation models in most of the experimental configurations.