"Knowledge is power"

- Sir Francis Bacon


"Knowledge is power if you know it about the right person."

- Ethel Mumford


"It's not what you know, it's who you know."



What is a social network?

A network is any group of interconnected things.

Computer networks

Road networks

Networks are often depicted visually by nodes and ties.

In the case of social networks, nodes are people and the ties represent the types of relations between people.

What is social network analysis?

Rather than observing the attributes of individuals, we focus on the relationships between actors in a network. By mapping how organizations of people are connected, researchers can reveal ways that networks influence the world.

Who knows who (video):

Small world phenomenon

In 1967, Stanley Milgram made the famous “small world experiment” which claimed to prove that people in the world are separated by at most 6 links. While the experiment is considered to have many flaws, the notion of six degrees of separation has persisted in popular culture.

6 degrees of Kevin Bacon

What are weak ties? Why are they valuable?

In 1973 a sociologist named Mark Granovetter wrote a paper called "the Strength of Weak Ties". He studied how people get jobs and found that most frequently they got them from loose acquaintances (weak ties) rather than from people close to them.

Weak ties are a source of novel information and therefore incredibly valuable. Groups with close ties (families, friends) tend to have access to and recirculate the same information.

In this model, individuals with who can broker connections between social networks exercise influence (power).


Enron Explorer

Mark Lombardi

Mapping terror networks

Musical affinities


Other social network projects

Social Networking Websites

These are online services that attempt to enhance the abilities of communities of people who share common interests to create social networks.

The common features of these websites are the ability to construct an identity (profile) and then to publicly display your connections to other online identities. Users can subsequently traverse the resulting network.






Who cares?

- the top 10 social networking sites (MySpace, Blogger, YouTube, Facebook) are attracting nearly 50% of all web users [article]

- Facebook may be valued at nearly $10 billion [article]



Issues and Directions

Privacy - where is the line between public and private. Is there even a line anymore?

Mobile social networks