Understanding Cross-site Linking in Online Social Networks

1. Understanding Cross-site Linking inOnline Social Networks Yang Chen1, Chenfan Zhuang2, Qiang Cao1, Pan Hui3 1Duke University 2Tsinghua University 3Hong Kong University of Science and Technology

2. Motivation • A number of OSN sites with different functionality • It is quite common for an individual user to have multiple accounts on different OSN sites. • How to efficiently manage accounts on different OSNs? Interact with friends Share breaking news Location-centric social interactions Job search

3. The Cross-site LinkingFunction The cross-site linking function allows a user to link her account on one OSN site to her accounts on other OSN sites

4. Cross-site Linking: Advantages • Make cross-site content posting easy • Help Foursquare users automatically post tips to Facebook and Twitter • Avoid repeated efforts in social connection establishment • Import the contact list from other OSNs • Provide more information of a user • Visit the linked profiles on other OSNs

5. Why Foursquare? • A representative LBSN service, one of the most popular OSN sites • Foursquare app: customized discovery and recommendation engine • Swarm app: real-time location sharing with friends • Supports the cross-site linking function • A user can link his profile to Facebook/Twitter • Every Foursquare user has a public profile page (http://foursquare.com/user/ID/)

6. Data Collection • Goal: analyze the entire Foursquare user base • To avoid the disadvantages of biased sampling • Challenge: IP-based rate limiting • Crowd crawling:100 crawlers around the United States, each crawls one chunk of IDs • Data • Collected between Jul. 22th, 2014 and Jul. 29th, 2014 • Public profiles of 51.15 million Foursquare users • Almost all (if not all) Foursquare users

7. Linking Options Percentage Distribution of Linking Options • About 60% Foursquare users have enabled the cross-site linking function • 56.15% users have added their Facebook accounts • 15.78% users have added their Twitter accounts The cross-site linking function is widely used among Foursquare users

8. Group-based Analysis: Gender • Gender options: • 51.52% Male • 42.92% Female • 5.56% Rather not say Very little difference between male users and female users in terms of the distribution of linking options

9. Group-based Analysis: Country • Top four countries: • USA (27.61%) • Turkey (9.49%) • Indonesia (8.17%) • Brazil (7.04%) Percentage of users that have enabled cross-site linking

10. Group-based Analysis: Activity • Two factors: social connections and location-centric activities (leaving tips, check-ins)

11. Group-based Analysis: Activity (cont.) • Most zombies/loners have not enabled cross-site linking, as they are socially isolated. • Watchers v.s. Orindary users • Watchers are less motivated to link to Twitter, as they don’t publish • 73% watchers and 71% ordinary users have linked to Facebook (users from both groups are connected with other Foursquare users)

12. Behavioral Difference among Users with Different Linking Options • Users who have enabled the cross-site linking function are more “active” • Cross-site linking will deliver published contents to more prospective audience • “TW only” > “FB only” • Publicly viewable tweets can be quickly spread through the Twitter network • FB user status is only visible to friends by default (fewer possible audiences)

13. User Privacy Concerns & Cross-site Linking Alice’s Facebook Profile More information about Alice!! Alice’s Twitter Profile Alice’s Foursquare Profile Intuitively, cross-site linking might cause concerns for users who care a lot about their privacy. In Foursquare, users can customize their profiles according to privacy concerns (a user can choose whether to enable an optional field)

14. User Privacy Concerns & Cross-site Linking (cont.) • Whether or not uploading personalized profile photo is an indicator for the adoption of cross-site linking • Enabling any of the five optional field indicates a higher probability of using the cross-site linking function

15. Cross-site Information Consistency A user might choose to expose the same or different personal information on different sites Cross-site Information Consistency (“Foursquare-Facebook”) Users have a high probability to manifest cross-site information consistency

16. Cross-site Information Aggregation • Aggregate the information of the same user from different OSN sites (learn more about a user) • Applications: friend suggestion, point-of-interest recommendation, personalized advertising, … • Example: gender-based analysis of Twitter

17. Gender-based Analysis of Twitter Female users publish more tweets Male users are involved in more lists

18. Gender-based Analysis of Twitter (cont.) The Use of Optional Fields (%) • Male users have a higher probability to add a URL • Both male and female users have a nearly 63% probability of adding a description, and a nearly 57% probability to add the location information.

19. Related Work • Cross-OSN linking papers • Ottoni et al. [ICWSM 2014]: Pinterest-Twitter linking • Chen et al. [WOSN 2012]: Google+ • Both of them used biasedsampling methods, while our study is based on the entire Foursquare user population • Wang et al. [IEEE Internet Computing, 2014] compared a series of user activities across Foursquare, Facebook, and Twitter • We focus on the cross-site linking function • Goga et al. [WWW 2013], Liu et al. [SIGMOD 2014] investigated how to identify accounts on different OSNs that all are owned by the same user • Useful for the OSN sites which do not support the cross-site linking function

20. Conclusion • About 60% of Foursquare users have enabled the cross-site linking function, and these users are more active than other users • Adding contents to an optional fieldindicates a higher probability of activating the cross-site linking function • If a Foursquare user has linked his account to Facebook, he will have a high chance to provide consistent information to both Foursquare and Facebook • The use of cross-site information aggregation helps us investigate the gender difference in using Twitter

21. Future Work • Investigate cross-site links among more mainstream OSN sites • Discover general patterns to characterize cross-OSN links • A volunteer-based study • Access the non-publicly viewable data (e.g.: check-in history) a deeper investigation into cross-site information aggregation • Build practical services/applications based on cross-site links • Malicious account detection