COM 411

Today’s Dad Joke

Bro, can you pass me that leaflet?



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

Reflection summary

  • Good
    • Activities
    • Class discussion
  • Bad
    • 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.



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

Undirected: Multiply by 2


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?
  • Did this make you think differently about metadata?
    • About privacy?


  • Reading
  • Keep working on R