Social Network AnalysisChallenges

Cécile Bothorel

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 2

Social Network Analysis

User's point of view Analyst point of view

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 3

An old field of Social Sciences

1933 : sociogram by Jacob Levy Moreno to map relationships

1954 : John A. Barnes introduces "social network"

1967 : Six degrees of separation by Stanley Milgram

1973 : "The Strength of Weak Ties" by Mark L. Granovetter http://fr.wikipedia.org/wiki/Fichier:Six_degrees_of_separation.png

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 4

A new umbrella term: Complex Networks

Real data in a wide variety of sources• Biology, physics,

finance, medecine, transportation, computer sciences

What's in common?Understand • General properties,

structure, evolution, propagation

Macroscopic structure of the web, late 1990s

• 2 Altavista crawls each with over 200 million pages and 1.5 billion links

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 5

(very) big, rich and dynamic graphs

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 6

(very) big, rich and dynamic graphs

Now online social media available

A new computational social science

Challenges at every steps• Data management• Model design• Analysis : measures,

mining algorithms, propagation, evolution

• Visualisation

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 7

Data management

« Big data », cloud, parellelization

Privacy: anonymization not enough?

Data owners do not know how to exploit... and manage

Sources Acquisition Preparation Storage Update

[Backstrom et al. 2007]

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 8

Model

Explicit/implicit connections

Types of relationship Details interactions Profiles …..

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 9

Analysis - measures

Lots of measures But which ones?

Marketing KPI:

• Value of Rts in Twitter?

• Value of a fan Facebook? Expert-finding E-Reputation Recommendation, social Shopping

Prestige

Influence

RelevancePageRank

Centrality

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 10

Analysis – community detection

Hierarchical algorithms Modularity

maximisation Spectral partitioning

Evaluation? What is a good

partition?

[Fortunato 2010, Pons 2007]

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 11

Analysis – community detection

Structural partition only What about Augmented

Social network?• Additional information:

Users profile, shared contents, opinions, etc.

Network Dynamics?• Graph evolution [Leskovec

et al. 2005, 2008]• Link prediction [Liben-

Nowell and Kleinberg 2003]

[Cruz et al. 2010, 2011 Thèse Futur&Ruptures]

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 12

Analysis – propagation, virality

Influence - information propagation

Maximizing the spread of influence

Influence may come from outside the monitored data

Part of influence-based contagion and homophily-driven diffusion? Which factors affects the propagation ?

[Easley and Kleinberg 2010] [Leskovec et al. 2006, 2007]

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 13

Visualisation – for the end-user

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Visualisation – for the analyst

Open Tools: Gephi, Tulip, iGraph Plenty of measures, algorithms Volume of Data?

Artists in the last.fm database, by Tamas Nepusz

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 15

Visualisation – for the analyst

New layouts? Here: Analyse the interaction

between communities [Cruz et al. 2012,Thèse Futur&Ruptures]

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI 16

Visualisation – for the analyst

[Cruz et al. 2012, Thèse Futur&Ruptures]

Augmented social network exploration• Compare perspectives• Differents role assignation

Journées Futur & Ruptures, 26 January 2012Telecom Bretagne, LUSSI

Conclusion

http://http://labocommunicant.net/ppc/cecile-bothorel/

http://http://perso.telecom-bretagne.eu/cecilebothorel/

http://twitter.com/#!/CecileBothorel

Social network analysis: a renewed research area...

… to be challenged.

Various open questions & difficulties.

With sample of our contribution: Augmented Social Network Analysis, Futur&Ruptures PhD thesis, Institut Telecom

[F. Bonchi et al. 2011, Social network analysis and Mining for Business applications, ACM Trans. Intell. Syst. Technol.]