Friend Grouping Algorithms for Online Social Networks: preference, bias, and implications Motahhare Eslami, Amirhossein Aleyasen, Roshanak Zilouchian Moghaddam, and Karrie Karahalios University of Illinois at Urbana-Champaing, Computer Science Department, Urbana, IL, US {eslamim2,aleyase2,rzilouc2,kkarahal}@illinois.edu Abstract. Managing friendship relationships in social media is challenging due to the growing number of people in online social networks (OSNs). To deal with this challenge, OSNs’ users may rely on manually grouping friends with person- ally meaningful labels. However, manual grouping can become burdensome when users have to create multiple groups for various purposes such as privacy control, selective sharing, and filtering of content. More recently, recommendation-based grouping tools such as Facebook smart lists have been proposed to address this concern. In these tools, users must verify every single friend suggestion. This can hinder users’ adoption when creating large content sharing groups. In this paper, we proposed an automated friend grouping tool that applies three clustering al- gorithms on a Facebook friendship network to create groups of friends. Our goal was to uncover which algorithms were better suited for social network groupings and how these algorithms could be integrated into a grouping interface. In a series of semi-structured interviews, we asked people to evaluate and modify the group- ings created by each algorithm in our interface. We observed an overwhelming consensus among the participants in preferring this automated grouping approach to existing recommendation-based techniques such as Facebook smart lists. We also discovered that the automation created a significant bias in the final modified groups. Finally, we found that existing group scoring metrics do not translate well to OSN groupings–new metrics are needed. Based on these findings, we conclude with several design recommendations to improve automated friend grouping ap- proaches in OSNs. Keywords: Automated Grouping, Clustering Algorithms, Online Social Networks 1 Introduction Mailing lists, chat groups, Facebook lists, and Google+ circles are a few examples of tools that facilitate group creation in social media. We create groups to help us man- age large amounts of information, in this case people. By creating a mailing list for an alumni group, we no longer need to memorize a long list of names. Instead, we can recall the group name and use it for exchanging messages [9]. In the context of OSNs, in 2007, Facebook introduced friend lists, manually created lists of Facebook friends, for the purpose of selectively sharing and reading content [24]. Twitter introduced lists