1. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy Concerns vs. User Behavior in Community Question Answering Imrul Kayes USF Nicolas Kourtellis Telefonica Research Francesco Bonchi Yahoo Labs Adriana Iamnitchi USF

2. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Community Question Answering Sites CQA sites: Popular platforms – Yahoo Answers: 200M users, 5M users/day – Quora: 1M/month – Stack Exchange: 4M users (e.g., Stack Overflow) Functionalities: – Q/A posts & comments, social networking, leaderboards, and more. Why do we need them? – Not all web-searches are successful! – Complicated / intricate questions! 1

3. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Motivation Privacy of user data: important but unresolved issue Privacy vs. platform usability: – Public content is helpful but users would prefer privacy Privacy-aware users are more engaged (e.g., on FB) – Is there a sweet-spot? 2 Privacy Platform usability

4. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Main Idea Utilize users’ modifications on privacy settings as a proxy of privacy concerns Group users into privacy categories: 1.Public 2.Semi-private QA-private, Network-private 3.Private Study users’ engagement vs. privacy concerns – Use activity logs & privacy settings instead of surveys 3

5. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Outline CQA platforms Motivation Main idea Research Questions Yahoo Answers Dataset Results Proposals for CQA platforms improvements 4

6. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Motivating Research Questions 1.Are privacy-concerned users more engaged than public users? – Retention, social circles 2.Do privacy-concerned users contribute differently to the community than public users – Points, best answers 3.Do privacy-concerned users have different perception on answer quality than public users? – Thumbs up/down of best answers 5

7. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Motivating Research Questions 4.Are privacy-concerned users also more abuse- conscious? – Abuse reporting 5.Are privacy-concerned users more likely to violate community rules? – Deviance score 6

8. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Yahoo Answers Dataset 1.5M users (2012-2013) – 2.6M follower-followee ties (SN properties*) – LCC: 1.1M nodes (74%), 2.4M edges (92%) Keep active users with more than 10 Q/A (68%) 4 privacy settings: – All public (84.4%), PU – Hide content (Questions/Answers) (2.5%), QA – Hide network (Followers/Followees) (0.9%), N – Hide content & network (12.2%), PR 7 Public Semi- Private *Kayes et al. “The social world of content abusers in Community Question Answering“, WWW’2015

9. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Retention Semi-private users have higher inter-event time Private users have lower inter-event time 8

10. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Social Circles Indegree = #followers, Outdegree = #followees Privacy-concerned users have larger social circles Followers or followees 9

11. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Accomplishments Private & semi-private users have more points Privacy-concerned users contribute more in YA quantitatively 10

12. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Accomplishments best answer percentage (BAP Privacy-concerned users contribute more in YA qualitatively 11

13. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Best Answers Privacy-concerned users select more Best Answers 12

14. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Community feedback via thumbs up and down: Privacy-concerned users have more average thumbs on Best Answers Privacy & Best Answer Quality 13

15. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Abuse Reporting 90% of reports submitted by 8% of users Privacy-concerned users post more valid reports 14

16. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy & Deviance Deviance can indicate user engagement* Private > semi-private > public users’ deviance scores 15 * Kayes et al. “The social world of content abusers in community question answering“, WWW’2015

17. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Summary 1.87.20% public profiles (default) 2.Privacy-concerned users are more engaged: – higher retention – more social network contacts – contribute more & better content – higher perception on answer quality – better citizens in terms of reporting abuses – higher platform engagement (via deviance) 16

18. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Suggestions for better CQA platforms If privacy settings modified: – Likely commitment to the platform – Question recommendation and routing – Community moderation If privacy settings unmodified: – Incentivize for increased participation & retention Privacy settings in CQA sites – Prediction & recommendation via ML techniques 17

19. 7th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining Privacy Concerns vs. User Behavior in Community Question Answering Imrul Kayes USF Nicolas Kourtellis Telefonica Research Francesco Bonchi Yahoo Labs Adriana Iamnitchi USF Paper: http://arxiv.org/abs/1508.06184http://arxiv.org/abs/1508.06184 nicolas.kourtellis@telefonica.com Twitter: @kourtellis