Havard Business School has an interesting study titled Do Friends Influence Purchases in a Social Network?. I would like to get my hands on the raw data (which is from the Korean social site Cyworld), but the outline conclusions seems plausible:
Highly connected people are negatively influenced by purchases in their network. This is consistent with a hypothesis that they are trend leaders who are always looking for new things to differentiate themselves from their group.
Moderately connected people are positively influenced by purchases in their network. This is consistent with a hypothesis that these people are trying to “keep up with the Joneses”.
Weakly connected people (48% of the data set) are not influenced by purchases in their network. The paper rather offhandedly dismisses these people as “the low status group”.
Interesting study and worth considering the implications for your social network analysis. As an aside, I was talking yesterday to a Marketing software company who were exactly focusing on that middle segment in their default parameters for their SNA module. Clever.