Network Analysis in R

Networks: History & Terminology

In this section we will discuss

1. A, very brief, history of network analysis in academic literature
   • Grannovetter (1978) . . . forbidden tryads
2. Key terminology needed in discussing network attributes.
   • Measures of centrality
     • Degree
     • Betweeness
     • Closeness

History

Social networks have been a prominent part of sociological theory since the very beginning.

History

In 1978, Mark Granovetter published his seminal paper, The Strength of Weak Ties, which introduced a concise and coherent theory of how information flows in networks.

1. The Forbidden tryad

   [definition] If two people are connected to the same person, they are inherently connected.

Graph Centrality

It is often helpful to identify key people or nodes in graphs. Specific individuals – such as the company boss – can be specified before hand with prior knowledge.

But, just because an individual is the boss – and in a position of authority, they may not be influential within the network.

Measures of centraility help us better identify key nodes in a network graph.

An example

Suppose we have a network comprise of all group members in marketing company. This group has 4 team leaders. Looking at the graph below, which member is most closely connected to all others?

Degree

The degree of a graph vertex of a graph is the number of graph edges which touch.

Closeness

Closeness is the sum of the length of the shortest paths between the node and all other nodes in the graph. Thus the more central a node is, the closer it is to all other nodes.

Betweenness

The betweenness centrality for each vertex is the number of these shortest paths that pass through the vertex.