Applying Social Network Analysis on Blogospheres

This post summarizes SUN Wen-jun and QIU Hang-ming: "A Social Network Analysis on Blogospheres", in the International Conference on Management Science & Engineering (15th), Long Beach, USA, September, 2008.

Blogging has become a way that makes people socially interact together. you can follow somebody's else stories, comment on them, and refer to them sometimes without any distance restrictions between you and him/her or any techniqual knowledge of using the internet. That's why the blogosphere is considered a manifestation of a social network and reflects a kind of social relationship between users. A social network is defined as a collection of nodes (social actors) and links between the nodes (the interconnections) and the social network analysis (SNA) only cares about the relationships between the actors without any concern with the actors themselves.

Graph theory is one of the foundations of SNA and the formulation of social networks consists of a social graphs and a social relation matrices.
Common concepts of social network analysis:

1- Degree
The degree of a node is the number of links to this nodes. In a directed graph, there is an in degree and an out degree. The out degree of node i is the number of links pointing out of this node, and the in degree is the number of links pointing to this node. If both the in-degree and out-degree are zero, ten the node is called an isolated node.

2- Geodesic path
The shortest path between two nodes.

3- Geodesic distance
The distance of the geodesic path d(i, j) .

4- Diameter
The distance of the longest geodesic path. D= Max {d(i, j)}

5- Density
A measure of the closeness of a network. The more links between a particular number of nodes, the larger the density of the network.


ρ= 2l / n *(n − 1) for directed graph

ρ= l / n *(n − 1) for undirected graph

where ρ is the density, l is the number of links, and n is the number of the nodes.

6- Power and centrality
Social scientists measure power from the prespective of "relationship".
The centrality is used to express the concept of power. Centrality tells what central role a node plays in a social network.

Links categories
In a Blogosphere, the individual blogs are represented as nodes in the graph and the inter-links between them are directional links in the graph.
There are four categories of links:
1- The link put by the BSP (Blog Service Provider); these links are present on all blogs under the same blog site.
2- The citation of other blogs intentionally put in the page by the owner of the blog.
3- Links to other blogs in a special fixed location on a blog's page layout.
4- Links left by visitor of a blog in reviews and comments.