Link creation and profile alignment in the aNobii social network

Link creation and profile alignment in the aNobii social network

Luca Maria AielloGiancarlo Ruffo

Rossano Schifanella

Keywords : link creation, homophily, social influence, aNobii

2nd IEEE International Conference on Social Computing

Speaker:Luca Maria Aiello, PhD student

[email protected]

Alain BarratCiro Cattuto

Authors:Università degli Studi di Torino ISI Foundation

SocialCom 2010 - Luca Maria Aiello, Università degli Studi di Torino 2

Open questions in social network analysis

1. What are the dynamics leading to link creation?

2. What is the interplay between user similarity and link creation?

22/08/2010

SocialCom 2010 - Luca Maria Aiello, Università degli Studi di Torino 322/08/2010

• Dataset• Static analysis• Geographic analysis

• Dynamical analysis

• Conclusions

Outline




• Conclusions

Outline

5

Social network for bookwormsData-driven analysis on anobii.com

22/08/2010 SocialCom 2010 - Luca Maria Aiello, Università degli Studi di Torino

Social network◦Directed◦Friendship + neighborhood

Profile features◦ Library and wishlist◦Groups ◦Tags

4th snapshot Friendship Neighborhood Union

Nodes 74,908 54,590 86,800

Links 268,655 429,482 697,910

6 snapshots, 15 days apartFull giant connected component




• Conclusions

Outline

7

Basic statistics<kout> 8.0

Reciprocation 0.57Avg SPL 5.3Diameter 20


Broad distributions

High reciprocation

High diameter


Correlations and mixing patternsPearson correlation

kout ng nb nw

kout1 0.31 0.18 0.18

ng1 0.32 0.31

nb1 0.22

22/08/2010

Positive correlations between:Connectivity and

activityDifferent activities

Assortativity (n.s.)


Profile similarity vs. social distance

Topical overlapStatistical correlation because of assortative biases?Null model to discern real overlap from purely statistical

effects◦No topical overlap other than that caused by statistical

mixing patters22/08/2010

vnun

bbvu

bb

b vub

,

Does similarity between user profiles depend on the social distance?




• Conclusions

Outline


Motivations

…does geographical overlap hold in the network as well?

Dataset peculiarities◦Many users specify their home country (97%) or

town (38%)◦Particular community distribution

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12

Geographical clustering


Country-level social network

Zoom on Italy


Geographic and language overlap

Null model test with random link rewireCountry-level overlap due to language barriersCity-level overlap for friendship (trivial…)City-level overlap for neighborhood

◦ Bidirectional causality connection between acquaintance in real life and connectivity in the online social network22/08/2010




• Conclusions

Outline


Triadic closure

Reciprocation is strongUsers tend to choose “friends of their friends”

as new friends

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Direct Reciprocated BidirectionalClosure

Doubleclosure

75% 20% 25%30% 10%

Classification of new links at time t+1 between nodes already present at time t (t ∈ {1,…,5})


Proximity-driven attachment

Users tend to choose “friends of their friends” or people close in the social network as new friends

This process results in preferential attachment22/08/2010


Causality between similarity and link creation

Topical overlap is observed for all profile features

Three possible explanations:1. Homophily (people connect with similar people)2. Social influence (social connection conveys

similarity)3. Mixture of the two

Explore the causality relationship between profile similarity and social linking

22/08/2010

What is the cause of topical overlap?


Similarity link creation

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⟨ncb⟩ σb ⟨ncg⟩ σg

duv = 2 9.5 0.02 1.12 0.05

u → v 12.9 0.04 1.10 0.08

u ↔ v 18.5 0.04 1.67 0.11Closure 18.2 0.04 1.81 0.10Dbl closure 23.4 0.05 1.20 0.12

Average similarity of pairs forming new links between t0 and t0+1 (t0=4), compared with average similarity of all the pairs at distance 2 at time t0

Pairs that are going to get connected show a substantially higher similarity


Link creation similarity

22/08/2010

Evolution of the similarity between pairs linking together at different times

Groups

Books




• Conclusions

Outline

21

SummaryWhat are the dynamics that rule link creation?

◦ Reciprocation (in direct networks)◦ Triadic closure◦ Proximity-driven (preferential) attachment

On geographical space On the social network

◦ Language-driven attachment◦ Homophily

What is the interplay between user similarity and link creation?

◦ Tight coupling (topical overlap)◦ Topical overlap is caused by homophily and social

influence both



Future work

Link predictionInformation spreadingExtend analysis to other social systems

22/08/2010

Speaker: Luca Maria [email protected]

www.di.unito.it/~aiello

Thank you for your attention!

2nd IEEE International Conference on Social Computing

Documents

Link creation and profile alignment in the aNobii social network