Social Influence vs. Selection

First, a couple of definitions:
* Selection is a person's characteristics (mutable or immutable) that drive link (friendship) creation.
* Social Influence is the propensity of a person's friendships to drive characteristics.

The first, for example, would be an ethnic group finding a neighborhood where members of the same group live. The second would be how the discovery of a new music act by one friend drives the adoption of the same act by their friends.

I came across some research that looks at selection vs social influence in the context of page editors of wikipedia. The question posed is, how does friendship influence the pages editors work on? How Crandall et al approached this was to look at the similarity (ie the number of common articles they edited) between two editors pre- and post- meeting.

The following graph is an aggregate/ average of many pairs of editors, but the surprising conclusion is the positive-linear nature of similarity and the ramp up/down surrounding when the meet. Of course, there's a level of historical retrospective going on here (looking at behaviors of people that met in the past), but it's interesting to see the build up pre-meeting (selection) and the continued ramp post-meeting (social influence).


Here's the full presentation from "Proceeding of the 14th ACM SIGKDD international conference on Knowledge discovery and data mining":

Feedback Effects Between Similarity And Social Influence In Online Communities

View more presentations from Paolo Massa.