Coast to Coast Seminar Series Fall 2015: "Recommender Systems: Exploiting Big User Feedback Data for Personalization"

Tuesday, September 22, 2015
11:30 - 12:30

Dr Martin Ester
Computing Science, Simon Fraser University


With the dramatic growth of internet-based services, increasingly large numbers of items, such as web pages, videos, products etc. become available to users. To cope with the information overload, users demand a personalized selection of items that are relevant to their needs, but are typically not willing to spend much effort on specifying their personal needs. This has motivated the development of recommender systems, which automatically learn the user needs from available user feedback data. Feedback data can be explicit, e.g. ratings of movies, or implicit, e.g. clickstream data which records parts of the screen a user clicks on. The idea of Collaborative Filtering (CF) is to exploit big feedback data from many users to make recommendations to each individual user, assuming that users that have provided similar feedback on some items are likely to have similar feedback on further items. In this talk, we will briefly introduce matrix factorization as a state-of-the-art method to implement CF. We will then present two of our own research projects that explore the potential of social media for improving the quality of recommendations. First, we will show how to leverage a social network among users and the well-known effects of social influence and selection. Second, we will present an approach that also considers textual feedback data, i.e. product reviews, to create more fine-grained recommendations taking into account that user feedback may be based on different aspects of an item. While recommender systems have been successful in many personalization tasks, they come with their own risks. We will conclude the talk with a discussion of privacy issues, in particular in the context of social networks, and the so-called “filter bubble”, the phenomenon that due to personalization users do not get exposed to information that could challenge their worldview.

About the Speaker

Martin Ester received a PhD in Computer Science from ETH Zurich, Switzerland, in 1989 with a thesis on knowledge-based systems and logic programming. He has been working for Swissair developing expert systems before he joined University of Munich as an Assistant Professor in 1993. Since November 2001, he has been an Associate Professor, now Full Professor at the School of Computing Science of Simon Fraser University, where he co-directs the Database and Data mining research lab. From May 2010 to April 2015, he has served as the School Director. Dr. Ester has published extensively in the top conferences and journals of his field such as ACM SIGKDD, WWW, ICDM and ACM RecSys. According to Google Scholar, his publications have received more than 17000 citations, and his h-index is 48. He received the KDD 2014 Test of Time Award for his paper on DBSCAN. Martin Ester’s current research interests include social network analysis, recommender systems, opinion mining, biological network analysis and data mining for personalized medicine.