The Decline and Fall of Social Networks

Friendster Collapse - the reverse S curve


Interesting article in MIT Review of research looking at why Social Networks collapse (carried out by another of the great Technology universities, the Swiss Federal Institute of Technology in Zurich - here is the paper). In short it's about cost/benefit (or hassle factors, as they were once called) and the number of friends people on average have on the network (the k-core score):

1. Cost/Benefit

When the costs–the time and effort–associated with being a member of a social network outweigh the benefits, then the conditions are ripe for a general exodus. The thinking is that if one person leaves, then his or her friends become more likely to leave as well and this can cascade through the network causing a collapse in membership.

2. k-core

If a large fraction of people on a network have only two friends, it is highly vulnerable to collapse. That’s because when a single person exits, it leaves somebody with only one friend. This person is then likely to exit leaving another with only one friend and so on. The result is a cascade of exits that sweeps through the network. However, if a large fraction of people on the network have, say, ten friends, the loss of one friend is much less likely to trigger a cascade.

Be interesting to see if there is any maths about the interplay of these - is the cost benefit a slow rise thing or a step "last straw" thing? Is there an 80/20 k-core number, where a "state change" occurs, or does stickiness increase with connections linearly, or maybe by Metcalfe's Law?

Anyway, as the paper notes, Friendster got it wrong and everyone left. However, there was a 3rd factor operating then which isn't right now, viz:

3. Where else would they go? Friendster fell apart in a world with Facebook, MySpace and Bebo, so the collapse was very fast. Today, where would one go? Wouldn't a Facebook collapse just be a slow tailing off of activity as the cost/benefit rises, (as is happening in the early facebook countries in fact), but there is not a clear go to alternative Social Network.

Now THAT is the factor to really watch methinks