Detecting social networks via email

Detecting social networks via email. The trio wondered if they could identify distinct communities within Hewlett-Packard's research lab simply by analysing the IT manager's log of nearly 200,000 internal emails sent by 485 employees over a couple of months.

They plotted the links between people who had exchanged at least 30 emails with each other, and found the plot included 1110 links between 367 people. In a network as large and complex as this, the plot alone will not tell you which groups people are.

So to pick them out, the researchers used a computer algorithm that looks for the critical links that form bridges between separate groups – what the team calls links with high “betweenness”. By severing these links one by one, the algorithm gradually isolates people into different communities of groups who are emailing each other.

To make sure the order in which links are severed does not distort the picture, the team repeated the task 50 times, each time cutting a different link first. Most individuals popped up in the same group every time; they were excluded from a group only if they failed to appear in it at least four times. [Smart Mobs]

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