1. Human-Computer Interaction Institute, School of Computer Science, Carnegie Mellon University, Pittsburgh, PA 15206
2. Sony Computer Science Laboratoires, Inc., Tokyo 141-0022, Japan
3. Okinawa Institute of Science and Technology Graduate University, Onna son, Okinawa 904-0412, Japan
4. Yale Institute for Network Science, Yale University, New Haven, CT 06520
5. Department of Sociology, Yale University, New Haven, CT 06520
6. Department of Statistics and Data Science, Yale University, New Haven, CT 06520