  We address the question of how participants in a small world experiment are
able to find short paths in a social network using only local information about
their immediate contacts. We simulate such experiments on a network of actual
email contacts within an organization as well as on a student social networking
website. On the email network we find that small world search strategies using
a contact's position in physical space or in an organizational hierarchy
relative to the target can effectively be used to locate most individuals.
However, we find that in the online student network, where the data is
incomplete and hierarchical structures are not well defined, local search
strategies are less effective. We compare our findings to recent theoretical
hypotheses about underlying social structure that would enable these simple
search strategies to succeed and discuss the implications to social software
design.
