Lecture 13 - Influencing People in Social Networks

Facebook is…

The largest social networking site today.

Measuring Influential Power: Analysis

Companies charting influential power on Twitter through followers and retweets.

Measuring Influential Power: Synthesis

Marketing campaigns buy off influential people and seed them with products.

Social Graph:

Illustrates soical relationships

Nodes

Are people

Links

Relationship between nodes

Centrality

Measure of node importance

Degree Centrality

Number of nodes connected to node, do not need to distinguish in-degree and out-degree.

Closeness Centrality

Degree does not factor in distance. Refers to number of links on path between two nodes.

Path

Set of links connecting two nodes

Shortest Path

Path between two nodes with shortest distance

Diameter

Longest of the shortest paths considering all node pairs

To find the closeness centrality for each node:

Find shortest path lengths to others and then take average of these (divide)

Closeness = 1 / average shortest path length

Betweenness Centrality

Want to factor “connectivity” in