title: An experimental study of search in global social networks.
abstract: We report on a global social-search experiment in which more than 60,000 e-mail users attempted to reach one of 18 target persons in 13 countries by forwarding messages to acquaintances. We find that successful social search is conducted primarily through intermediate to weak strength ties, does not require highly connected "hubs" to succeed, and, in contrast to unsuccessful social search, disproportionately relies on professional relationships. By accounting for the attrition of message chains, we estimate that social searches can reach their targets in a median of five to seven steps, depending on the separation of source and target, although small variations in chain lengths and participation rates generate large differences in target reachability. We conclude that although global social networks are, in principle, searchable, actual success depends sensitively on individual incentives.
authors.affiliation: Institute for Social and Economic Research and Policy, Columbia University, 420 West 118th Street, New York, NY 10027, USA.
authors.forename: Peter Sheridan
authors.initials: PS
authors.lastname: Dodds
authors.forename: Roby
authors.initials: R
authors.lastname: Muhamad
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Watts
mesh_terms: D034742:Electronic Mail; D005190:Family; D005260:Female; D033062:Friends; D006801:Humans; D020407:Internet; D007398:Interpersonal Relations; D008297:Male; D035781:Siblings; D012944:Social Support; D014937:Work