What, Why, HOW

Lately I've gone through roughly 15 books about social psychology, crowd behavior, group emotions contagion, irrationality, and topics involving people in the society, don't panic, just for fun, no special academic interest really. It seems to me that they can be either categorized as theoretical or empirical, easy to understand right? For theoretical books, they are more like textbooks, emphasizing on definitions, principles and some sort of related examples, yuck. While for empirical thesis, more experiment-oriented, more human factors involved, and more lively. The approaches scientist/ psychologists adopt to get clear of a question is actually extremely similar: background - theory proposal - experiment - result - conclusion. It's fun to watch people acting as candidates, being tested, sometimes not aware, and giving out unexpected results at the end. Here strongly recommend Dan Ariely's books. What a fun guy!

These book enlightened me about the reason to carry out studies, the utility to define new stuff, the reason of existence of all the experiments and theories. Because if they serve only to stuff the bookshelf and can't be utilized to do anything, then they are purely junk.

So here it go. I want to concisely evaluate the utility of several factors that we calculate for SNA. I've put all stuff in my own words, so they are really lifelike and trivial...So what do they describe, and why them?

HOW -- lecture notes thanks... = =

WHAT:
Let's see some SNA analysis key factors:

Degree centrality:
the more neighbor an actor has, the easier it is for him to catch new information
Closeness centrality:
the smaller the distance, the larger the speed to spread information
Betweenness centrality:
the number of times an actor acts as a bridge along the shortest path between two other actors -- the participation of the actor during high-efficiency information propagation (since only shortest lines are counted)

WHY:
I always believe things exist for a reason, and the reason why these factor exist in the place of others is their unique irreplaceable usage.

These three factors describe the connectivity, distance and intermediate function of an entity. Imagine the flow of information: income from a neighbor->outcome to all neighbor->propagate. That's correspondingly related to degree, betweenness and closeness.  Degree stands for the incoming power, betweenness describes the probability of occurence of such an action, and closeness gives the flow of information, which is a continuous process.

No matter the object is an actor or a group as a whole (as when a group is treated as a whole, it's again an actor), these three factors ideally define the life cycle of information propagation. And why not other factors like "location", "traffic load", etc? Because the fundamental structure of a network is defined by the connectivity and relationship between people (that's why we call it social network).

So here's my belief: they exist to serve functions. And there's no need to panic about the dirty maths, since after all, it's just maths. What's lying behind is the true thing that matters.

HOW
Finally I plan to go back to where I started with. It seems that we've learnt many theoretical ideas in the class. Even given some examples, it still appears quite distant from us. So to fully comprehend the idea behind SNA as well as to utilize SNA, we should design our own experiments, implement our own analysis systems to really get to know social networking. Maths is maths if left alone, however maths is everything if combined with real life cases. That's really why we need SNA and how SNA can help us mine data, grab the essence of the trends of social networks, and come up with brand-new solutions.