[1] GESIS Leibniz Inst Social Sci, Cologne, Germany
[2] GESIS Leibniz Inst Social Sci, Computat Social Sci Dept, Cologne, Germany
[3] Univ Oberta Catalunya, Barcelona, Spain
[4] Princeton Univ, Polit & Publ Affairs, Princeton, NJ USA
[5] Princeton Univ, Ctr Informat Technol Policy, Princeton, NJ USA
[6] Amer Univ, Washington, DC USA
[7] Univ Calif Davis, Davis, CA USA
[8] Univ Mannheim, Sch Social Sci, Mannheim, Germany
[9] Univ Amsterdam, Amsterdam Sch Commun Res, Amsterdam, Netherlands
[10] GESIS Leibniz Inst SocialSciences, Dept Computat Social Sci, D-50667 Cologne, Germany