Community participation - Joseph Rowntree Foundation

Network dynamics: explaining the pattern
Inequity
Preferential attachment
The social networks surrounding community participation structures in Ely and Benchill
are characterised by a common signature: a few ‘nodes’ (e.g. people or institutions)
have a very large number of connections to other nodes and a much larger number of
nodes have only a few connections. We saw in the last chapter, for example, that Jim
sat on the committee of the Tenants and Residents Association, the Communities First
partnership and the Patient Reference Panel, while Brenda was a governor of two
schools and sat on the board of the Wythenshawe Forum and the SRB partnership.
It turns out that this pattern of a few nodes having a lot of links is a pervasive feature
of contemporary social organisation not confined to community participation. 4
A key idea in trying to explain this phenomenon is what has been termed ‘preferential
attachment’. 5 Suppose that, every time a new node joined a network, it formed a link
with an existing node at random. In that case, we would expect the distribution of
links to be roughly even, some having a few more, some a few less, but no wild
differences between the two. This is clearly not what has happened in Ely and
Benchill. That’s because, in reality, networks don’t tend to work that way. A new node
in the network is less likely to form a link at random than to try to link to a node that
already has a number of connections, because that will be more useful.
To illustrate, think about the strategies that airlines use when developing their routes.
If you wanted to fly from, say, Exeter to Detroit, you would be unlikely to find an
airline offering a direct flight. Instead, you might fly from Exeter to Paris, from Paris to
Newark and from Newark to Detroit. This is what is known as a ‘hub and spoke’
system – flights are routed from a cluster of smaller airports (e.g. Exeter) to a large
central airport or ‘hub’ (e.g. Paris). From there, passengers take flights on common
routes (‘spokes’) to other hub airports (e.g. Newark), from whence they can catch
connecting flights to their final destination (e.g. Detroit). So, when an airline wants to
start flying from a new airport, the best option will be to put on a route to an existing
hub airport. That way, passengers from the new airport will be able to choose from
the widest possible range of final destinations. In other words, rather than form a link
at random, the new node in the network connects to a node that already has many
other links. But, crucially, each time this happens, it makes it more likely that it will
happen again in the future, because it adds yet another destination that passengers
can reach by initially flying to the hub airport. In short, the more links a node in a
network has, the more attractive it becomes to others, and the more likely it is to
acquire new links as a result. This is the law of preferential attachment.
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