1. Human-Computer Interaction Institute, Carnegie Mellon University, United States and GroupLens Research, University of Minnesota, USA
2. GroupLens Research, University of Minnesota, United States and School of Computer Science, Carnegie Mellon University, USA
3. Human-Computer Interaction Institute, Carnegie Mellon University, United States
4. University of California, Berkeley, United States
5. School of Computer Science, Carnegie Mellon University, United States
6. Human Computer Interaction Institute, Carnegie Mellon University, United States