Models of influence propagation in social networks

1. Social Networks
Information Cascades and
Viral Marketing
Saturday, September 8, 12

2. Which
restaurant to
choose?
conformity
Saturday, September 8, 12

3. Information cascade
making the same decision that the others have
made, independently of the own private
information signals
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4. Information cascade
Sequential decision making
Incomplete information
The choice of previous participants is known
(but no the reasons!)
Limited selection space
Rational decision making
A posteriori probability (Bayes’ theorem)
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5. Information spread
Medium:
network structure
Model:
distribution mechanism
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6. Universal structure of
social networks
Power low degree distribution
Gigantic connected component
Small world phenomenon
Large clustering coefficient
Hierarchical structure
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7. Diffusion model
method - diffusion
virus model
“infected” on contact
probability depends on
immunity
can model
news
gossips
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8. Diffusion model
Step 1
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9. Diffusion model
Step 2
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10. Diffusion model
Step 3
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11. Diffusion model
Step 4
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12. Diffusion model
Step 5
Complete coverage
Process time depends
on the source
Based on connectivity
pattern
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13. Threshold model
neighbors “opinion”
decision threshold
information cascade
can model
beliefs propagation A,B - types of behavior
purchasing decisions q –decision threshold
spread of innovations If fraction of neighbors with A
greater than q, accpet A
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14. Threshold model
threshold= 1/2
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15. Threshold model
Step 1
2 sources
threshold= 2/5
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16. Threshold model
Step 2
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17. Threshold model
Step 3
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18. Threshold model
Step 4
incomplete cascade
depends on network
topology
strongly depends on
source selection
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19. Complete cascades
Strategic source placement
Well connected
Inside various communities
Increase of competitive advantage
reduce threshold level
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20. “The Dynamics of Viral
Product recommendation network
Marketing”
J. Leskovec et al, 2007
(DVDs)
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21. #newsjp
Twitter
retweet #ocra
mention
“Truthy” Project. Center for Complex Networks and System
Research. Indiana University.
#iraq
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22. Saturday, September 8, 12