ICWSM Session #1: Community

Gesundheit! Modeling Contagion through Facebook News Feed

How do ideas spread on social networks?  Some people say you have to get ‘influencers’ to spread the word.  More recently, Watts and others are saying anyone can really start the propogation.  Did a study on Facebook news feeds.

I thought it was interesting that one person doesn’t really start a chain of ideas.  Rather, cliques kind of join together to create one large connected network.  So its not really as important to influence the influencers.  If you can get ‘the people’ behind your idea, the idea kind of propogates on its own.

Seeking and Offering Expertise across Categories

About a Chinese Question/Answer site, simlar to Yahoo! Answers, where users spend and earn points based on asking and answering questions (users offer a certain number of points in answering questions).

Community Structure and Information Flow in Usenet:
Improving Analysis with a Thread Ownership Model

This is another examination of idea diffussion through a network.  This time on the Usenet network.  This one is a much larger sample than the Gesundheit paper — 19.6M articles, (6.2M cross-posted) over 4.5 years (1/04-6/08)

Found a Power-law relationship between # authors and # edges.

Also looked at Reciprocity: percentage of mutual reply edges.  Reciprocity is high in European groups

Similarity beween groups: Jaccard coefficient for cross-posts.  # shared articles betwen 2 groups / total number of articles in group.  Can also do Shared Authors.  Drew some clusters, and network graphs (weighted edge on similarity)

Given those things, they propose an Thread Ownership Model – a way to define the portion of a reply thread that belongs to different groups (this helps address the cross-posting).    They define Devotion of an author to a group: Percent of articles exclusive to a group.