1. WorkShop on Community Question Answering on the Web
Communities of Yahoo! Answers and Baidu Zhidao: Complementing or Competing?
Baichuan Li, Michael R. Lyu, and Irwin King
Department of Computer Science and Engineering
The Chinese University of Hong Kong

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4. Community Question Answering
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5. Complementing and Competing
Collaboration
Help each other on many topics
Competing
Isolation
Small circles
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6. Research Objects Type International Domestic Language
Mainly in English
Chinese
Number of Users
> 200 million
>250 million
Daily Unique Visitors
About 10 million
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7. Data January, 2008 July 2010 May 2010 YA08 and BZ08 YA10 and BZ10
YA-Q and BZ-Q
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8. Research Problems Community structure User behaviors
What’s it?
Sub-communities
User behaviors
Top contributors and common users
Influence to question solving
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9. Analysis Social network analysis User behavior analysis
Community structures
Sub-Community detection
User behavior analysis
Community efficiency analysis
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10. Community Structures SCC: users who frequently help each other
IN: users who mainly ask questions
OUT: users who mainly answer questions
SCC: Strongly Connected Component
DC: Disconnected Component
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11. Sub-Community Detection23 5 1 10 2 6 24 7 16 8 3 4
YA08
YA10
BZ08
BZ10
Detecting Sub-communities
Louvain method (Blondel et al., 2008)
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12. Weighted Mean Entropy Complementing Competing
number of users in sub-community s
number of categories
number of questions user i asked (and/or) answered in category j
Complementing
Competing
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13. Behaviors of Top Contributors
Interaction between top contributors and their neighbors
Collaboration
YA08
YA10
Isolation
BZ08
BZ10
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14. Behaviors of Top Contributors
Component of top contributors
Top 100 users ranked by Indegree, Outdegree, and Degree
Overlapping
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15. Behaviors of Common Users
Limited Activity
Most users only ask or answer questions in a very few categories
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16. Behaviors of Common Users
User activity at category level
Number of answers per question
Asker-answerer rate
Category mapping
32 volunteers
Fleiss’ kappa
Similar category settings of YA and BZ
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17. Number of Answers per Question
>
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18. Brief Summary Similarities Differences
Sub-communities are formed in both YA and BZ
Similar category settings
Differences
Yahoo! Answers
Baidu Zhidao
Structure
a certain amount of asker-answerers
askers and answerers are dominant
User Behavior
people prefer to ask or answer questions and collaborate in more categories
most people (especially, top contributors) prefer to ask or answer questions in a few categories
Complementing
Competing
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19. Discussion Why? Which style do you prefer?
Advertising?
Get good answers quickly?
How to improve community engagement?
Point system doesn’t work?
Monetary rewards?
What about the future?
Social QA?
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20. Community Efficiency YA-Q and BZ-Q
3,000 questions each are chosen randomly
Track the states of these questions within two days
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21. Conclusion Reveal the communities of two leading CQA portals
Community structures
User behaviors
Temporal analysis
Yahoo! Answers: Complementing
Baidu Zhidao: Competing
Investigate the influence of community to the efficiency of question solving
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22. Future work How to design better CQA systems?
High question solving speed
High user satisfactory
Encourage participation
Reward system
Impact of community on question and answer quality
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23. Thank You!
Q&A

24. BACKUP SLIDES
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25. Asker-Answerer Rate
>
>
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26. Closeness
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27. Category Mapping
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