Affiliation: | 1. Department of Methodology and Statistics, Tilburg University, Room P1.106. PO Box 90153, , 5000LE Tilburg, the Netherlands;2. Department of Computer Science, Stanford University, 353 Serra Mall, , Stanford, CA 94305;3. Google Inc, 76 Ninth Avenue, 4th Floor, , New York, NY, 10011;4. Department of Communication, Stanford University, Room 300E, McClatchy Hall, , Stanford, CA 94305–2050, USA |