Detecting Communities in Science Blogs

Detecting Communities in Science Blogs Christina K. Pikas [email_address] http://terpconnect.umd.edu/~cpikas/ScienceBlogging

Problem Area
eScience includes using electronic tools both for conducting science and for communicating about science
There are an abundance of tools both online and offline to help scientists communicate
Lots of scientists and members of the interested public maintain blogs (~2500?)
Ultimate Questions: Why? With whom are scientists communicating? What are scientists communicating about? What is the value to the scientists and to science?

Specific Problem Addressed
What is the nature of the science blogosphere?
What is its shape?
Who are the central participants?
What is the connectivity?
Where are the potential information flows?

Outline
Background
Methods
Data gathering
Analysis
Results
Discussion

Background: Blogs
Defined by format
Individual posts, with permanent URLs
Comments
Links
In content
In blogroll
In comments and trackbacks
Community develops around single blogs and among blogs through commenting

Posts Links to Static Pages Links and automatically generated content http://dorigo.wordpress.com/

Access to posts by search and older posts using the calendar A list of most recent posts is automatically generated

A list of categories the blogger used to describe his posts. Clicking will list all of the posts in that category. The blogroll is a list of blogs the author reads or endorses to some extent. Access to the older posts by month.

The individual post page looks a lot like the blog home page

But with Comments, which may be signed with the the commenter’s URL And a form to leave your own comment. Typically your e-mail will not appear on the site

Background: Social Network Analysis
Uses connections between actors to understand potential flows of information and influence
Uses graph theoretic methods to find
Central or prestigious actors
Cohesive subgroups including communities

Methods: Sample Selection
Operational Definition of Science Blog
Blogs maintained by scientists that deal with any aspect of being a scientist
Blogs about scientific topics by non-scientists
Omitted
Primarily political speech
Ones maintained by corporations
Non-English language

Methods: Data Gathering
Two Networks: Links and Commenters
Link Data (Blogroll)
Used seed list developed in previous study using directories and searches
Snowball sampled using links from blogrolls
Visited and copied links
Commenter Data
Selected most central blogs from blogroll data
Used Perl scripts to pull the commenter URLs from each of the last 10 posts

Methods: Analysis
Used social network analysis and graphing software
Examined graph and calculated basic descriptive statistics
Found centrality and prestige measures
Degree: the links in and out
Betweenness: the number of shortest paths that flow through that node
Closeness: short paths to other nodes

Methods: Analysis
Located cohesive subgroups
Link methods
Components
LS Sets
Clustering methods
Community detection techniques
Newman-Girvan
Spin Glass

Results: Link Analysis (Blogroll)
One large component
There were 1091 nodes, 6621 arcs
Diameter is 9
In-degree ranges from 1 to 292, with the median in-degree of 3, and mean 6
10 of the top 20 blogs by in-degree are authored or co-authored by women
4 of the top 5 blogs by closeness are authored or co-authored by women

Results: Commenter
5 components, the largest with 911, others with 11 or fewer nodes
938 nodes (starting with the 46), 1152 arcs
The largest component has a diameter of 5

Discussion: Links (Blogroll)
Most of the blogs were connected in one dense component
A result of the diffusion of blogs?
There were a few very central blogs, and then many less central
Typical skewed distribution
The community of women scientists merits further study

Discussion: Commenters
Analysis easily located a notorious commenter who leaves incendiary comments on physics and chemistry blogs
High out-degree, no links in
Traffic on the women scientist blogs is more uniform, with frequent comments that are widely distributed among the blogs
Indicates a different use

Take Home Messages

The science blogosphere is densely connected with many opportunities for influence and information diffusion
Communities tend to form within disciplinary boundaries
An exception is the community of women scientist bloggers who are from many different disciplines

Acknowledgements
Thanks to Dr. Jen Golbeck for supervising this work as part of an independent study
Thanks also to
Dr. Alan Neustadtl for SNA advice
Dr. Dagobert Soergel for research advice

Christina K. Pikas
Doctoral Student
University of Maryland
College of Information Studies
[email_address]
http://terpconnect.umd.edu/~cpikas/ScienceBlogging

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Detecting Communities in Science Blogs

by Christina Pikas on Dec 10, 2008

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