Network Diameter

Average minimum distance between pairs of nodes

Complete network diameter = 1.0
  every node connected to every other node

Linear network of N nodes diameter = (N + 1) / 3

  node1---node2---node3---...---nodeN

Such regular networks generally have large diameters

Irregular networks generally have small diameters
  the "small world" phenomenon
  human acquaintanceship network diameter about 6.0