Social network analysis (SNA)

Social network analysis (SNA)

Social network analysis is the mapping and measuring of relationships and flows between people and community. Each participant in the community is called an actor and depicted as a node.  The nodes in the network are the people and groups while the links show relationships or flows between the nodes. Social network can be represented in graphical representation – Sociogram. This network effectively shows the distinction between the three most popular individual centrality measures: Degree Centrality, Betweenness Centrality, and Closeness Centrality.


SNA Measurements



 
Above social network can be represented in a matrix:

	Alice	Bob	Carol	David	Eva
Alice	-	1	1	1	0
Bob	1	-	0	1	0
Carol	1	0	-	1	0
David	1	1	1	-	1
Eva	0	0	0	1	-

Density

The density is used to measure the closeness of a network, is an indicator for the general level of connectedness of the graph.
Density = (L/ [g(g-1) / 2]) = 2* 6/20  = 0.6


Degree Centrality

Degree centrality of a node refers to the number of edges attached to the node.

	Alice	Bob	Carol	David	Eva
Degree centrality	3	2	2	4	1

Degree centrality can be normalized as below:

	Alice	Bob	Carol	David	Eva
Normalized	0.75	0.5	0.5	1	0.25

Closeness Centrality

An actor is considered important if he/she is relatively close to all other actors. Closeness represents the mean of the geodesic distances between some particular node and all other nodes connected with in

	Alice	Bob	Carol	David	Eva
Closeness centrality	0.2	0.17	0.17	0.25	0.14

Closeness centrality can be normalized as below:

	Alice	Bob	Carol	David	Eva
Normalized	0.8	0.67	0.67	1	0.57

We can find that David got the highest Closeness Centrality. He is most influential because he connected to all other nodes within the network.


Betweenness Centrality

Betweenness centrality is a measure of a node's centrality in a network equal to the number of shortest paths from all vertices to all others that pass through that node.

	Alice	Bob	Carol	David	Eva
Closeness centrality	0.5	0	0	3.5	0

Betweenness centrality can be normalized as below:

	Alice	Bob	Carol	David	Eva
Normalized	0.083	0	0	0.58	0

Result

After getting above measures for Social network analysis, we can find that David got the highest value both Degree Centrality, Closeness Centrality and Betweenness Centrality. David is the center within the social network and is the most influential one.

Second Post for Lecture 4-5

After having 2 more lectures, I learn more about Social Network. We have Social Media, Blogoshere and Social multimedia computing.

Social Media

In the world of Web 2.0, people share information on the internet. This facilitates interactions between people in social network. By making use of social media, people become easier to read information and share resource under Web 2.0.

Blogoshere

 People write blog to share information. If blogs are connected together to create a network, the bloggers form an online community. These kind of online community is very useful. Bloggers can share information in the network. Company also can prompt their product or find out potential client in the social network.

Social multimedia computing

Social multimedia computing makes the social network become more interactivity. Interaction-driven social networks become a major research topic of social network.. 

Direct Social Content Creation

 When we talk about Direct Social Content Creation, the most poplar web site is Wikipedia. Most of the people will think about Wikipedia firstly as an example of Direct Social Content Creation. Wikipedia allows users to create any kind of information. All users can write the content, edit and add recourse and relevant links. However, I think Direct Social Content Creation is everywhere in social network, such as Facebook, Blog, etc… 

After I shared some new or links in my Facebook, my friends may share their opinions on the same topic. We are writing some content on the same topic. It just like Direct Social Content Creation in Wikipedia. The difference is we only share the content to my friends inside Facebook instead of public in the internet. We cannot edit the format in Facebook like Wikipedia. However, the idea of creating the same content is the same. 

I wrote about Direct Social Content Creation in this article of my blog. After several people left comment to discuss Direct Social Content Creation on my article, we created an article about Direct Social Content Creation. The format of my article and comment is different from Wikipedia, but the idea is the same.

We can find that Social Network makes use of Direct Social Content Creation. Or we can say that our Social Network is also made up of Direct Social Content Creation.