Skip navigation

On Unexpectedness in Recommender Systems: Or How to Better Expect the Unexpected

Authors: Adamopoulos, Panagiotis
Tuzhilin, Alexander
Keywords: Algorithms, Design, Experimentation, Human Factors, Measurement, Performance, Evaluation, Novelty, Recommendations, Recommender Systems, Serendipity, Unexpectedness, Utility Theory
Issue Date: 19-Jun-2013
Series/Report no.: CBA-13-03;
Abstract: Although the broad social and business success of recommender systems has been achieved across several domains, there is still a long way to go in terms of user satisfaction. One of the key dimensions for significant improvement is the concept of unexpectedness. In this paper, we propose a method to improve user satisfaction by generating unexpected recommendations based on the utility theory of economics. In particular, we propose a new concept of unexpectedness as recommending to users those items that depart from what they expect from the system. We define and formalize the concept of unexpectedness and discuss how it differs from the related notions of novelty, serendipity, and diversity. Besides, we suggest several mechanisms for specifying the users’ expectations and propose specific performance metrics to measure the unexpectedness of recommendation lists.We also take into consideration the quality of recommendations using certain utility functions and present an algorithm for providing the users with unexpected recommendations of high quality that are hard to discover but fairly match their interests. Finally, we conduct several experiments on “real-world” data sets to compare our recommendation results with some other standard baseline methods. The proposed approach outperforms these baseline methods in terms of unexpectedness and other important metrics, such as coverage and aggregate diversity, while avoiding any accuracy loss.
Appears in Collections:Center for Business Analytics Working Papers

Files in This Item:
File Description SizeFormat 
Adamopoulos_13.03.pdf1.17 MBAdobe PDFView/Open

Items in FDA are protected by copyright, with all rights reserved, unless otherwise indicated.