Private Sharing of User Location over Online Social Networks
Social networks and information sharing
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Social networks and information sharing Lada Adamic
description
Social networks and information sharing. Lada Adamic. Outline. Individual contributors: Is narrow focus of benefit? Should they draw on knowledge in other disciplines? What motivates individuals to volunteer information? How does money and competition affect that motivation? The network: - PowerPoint PPT Presentation
Transcript of Social networks and information sharing
Social networks and information sharing
Lada Adamic
Outline
• Individual contributors:• Is narrow focus of benefit?• Should they draw on knowledge in other disciplines?• What motivates individuals to volunteer information?• How does money and competition affect that motivation?
• The network:• What role do social networks play in information diffusion?• Are online networks truthful and representative of trust?
• The information:• How does information change as it diffuses?
Focus and quality in knowledge contribution• study 4 knowledge contribution contexts
• scholarly publications (1900-2008)• patents (1976-2006)• Q&A forums (Yahoo! Answers, Baidu, Naver)• Wikipedia
• main finding:• focus trumps quantity in explaining quality of
contribution
Knowledge iN
Adamic, Wei, Yang, Nam, Clarkson, First Monday, 2010
Knows
Focus and knowledge contributionPATENTS PAPERS
WIKIPEDIA CQA
Impact of information diffusion across communities• study scholarly citation networks (JSTOR, patents)• does drawing from other areas (i.e. citing outside one’s
field) translate to having higher impact?• social sciences and humanities: no• natural sciences and patents: yes
Shi, Adamic, Tseng, PLoS One, 2009
Motivation and quality in information sharing• Analyze 2.6 million questions, 4.6 million
answers + 26 interviews of top answerers• Users who contribute more often and less
intermittently contribute higher quality information
• Users prefer to answer unanswered questions and to correct incorrect answers
• What motivates individuals to contribute in online Q&A forums?• altruism• learning• competition (point system)
Knowledge iN
Nam, Ackerman, & Adamic, CHI’2009
Monetary incentives and contribution• Crowdsourcing: 120 translation tasks
• all pay auction mechanism: participants contribute solutions, only 1 is selected to receive payment
• price treatment: high, low• shill treatment: enter in our own solution
as a user with or without prior success
• results• monetary incentives incentivize spam
(85% are machine translations)
• higher pay yields better contributions
• shills discourage other quality contributions
Liu, Yang, Adamic, Chen
Social dynamics of information in virtual spaces (e.g. Second Life)
• Items diffusing through social network spread more rapidly but have limited range
• Early adopters are distinct from connectors
• Sellers who chat with customers enjoy more repeat business, but social interaction doesn’t scale
Bakshy, Karrer Adamic EC’09,Bakshy,Simmons,Huffaker,Teng, Adamic, Best Paper @ ICWSM’10
Goal: • Understand basis of trust and friendship
• Understand causes of bias in online trust ratings
Data: • 600K CouchSurfing users, 3 million ratings
• Amazon & Epinions ratings
Findings: • When ratings are public, and when there is potential for reciprocity, ratings are overlypositive
Can online social networks be used as a proxy of trust and reputation?
I rate you. You rate me. Should we do so publicly? WOSN 2010
Design choices
?
Reciprocity in CouchSurfing
• Public friendship ratings are more highly correlated (rho = 0.73) than private trust ratings (rho = 0.39)
Can trust be equated with friendship?
• Close friendship -> high trust
• High trust -> variable friendship
• Trust and friendship strengthen over time, but rate varies by individual
Predicting trust (person to person “vouches”)
• Trust is localized/contextual• Trust is not the same as friendship• Global metrics do not perform as well as local ones
Variable Predictive accuracy:
Friendship degree 67.7%
Jaccard coefficient 55.8%
2-step vouch propagation 54.2%
PageRank 50.6%
Even “truthful” ratings may be biased
tracing information across the web
duration in days
leng
th o
f phr
ase
How do memes change as they diffuse length sentiment contentHow does their diffusion/evolution depend on the underlying network structure?
Simmons, Adar, Adamic
Simple Polya’s urn model of copying
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CDEF
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BCDE
For more information
• http://netsi.org Networks research group at the School of Information, University of Michigan
• [email protected]• Students:
• Xiaolin Shi (PhD 2009, now postdoc at Stanford)• Chun-Yuen Teng (current PhD student)• Matthew Simmons (current PhD student)• Xiao Wei (MSI 2010)
