# COM 411

Bro, can you pass me that leaflet?

Brochure.

## Housekeeping

• Thursday Dr. Lee will be visiting
• Next Thursday is an in-class exam

## Reflection summary

• Good
• Activities
• Class discussion
• Six Degrees book
• Sorry!
• Brightspace + wiki
• Not sorry ;)
• Confusing
• What kinds of goals to set?

## What to know from Six Degrees

• How closely connected are people who are geographically/socially distant?
• People are clustered: our friends are friends with each other, so it feels like it should be distant
• High clustering coefficient
• Human networks have short diameter
• We are all connected within a surprisingly small distance

## Homework Review

• Questions about networks in R?

# Power in Social Networks

## What is power?

• Long, varied history in the social sciences
• One version is the capacity to achieve one’s will
• How do we do that? Through capital
• Social networks are one way of measuring “social capital”
• Who has power in a social network?

## Degree Centrality

• Counts the number of edges each node has
• In, out, or all

## [1] "Degree Centrality:"
## 1 2 3 4 5 6 7 8
## 4 3 1 2 2 4 2 2

## Closeness Centrality

Average distance to all other nodes

## Betweenness Centrality

Counts the number of shortest paths that go through each node. This is based on the value of being in a “structural hole”

Which of these has the highest betweenness?

## Eigenvector Centrality

Who is connected to the most important people? If you have only one friend, but that friend is the President, then you are still powerful.

## Density

Directed $\frac{\sum(edges)}{N * (N-1)}$

Undirected: Multiply by 2

## Centralization

How unequal is the centrality between nodes?

## Using metadata to find Paul Revere

• Where did the data come from?
• What kind of network was it?