Core Periphery Model
Refers to the characteristic that successfull online collaborative communities often combine a highly engaged core leadership; with various degrees of soft participation by the more loosely affiliated periphery.
Comment by Ross Mayfield
"groupthink is avoided by a social network structure that allows a dynamic and diverse periphery to provide new ideas, but the core of the network needs to be tightly bound to be able to take action. That's the main point of Building Sustainable Communities through Network Building by Valdis Krebs and June Holley. When studying a community over time, they suggest a vibrant community is made up of four stages: 1) Scattered Clusters 2) Single Hub-and-Spoke 3) Multi-Hub Small-World Network 4) Core/Periphery The ideal core/periphery structure affords a densely linked core and a dynamic perhiphery. One pattern for social software that supports this is an intimacy gradient (privacy/openness), to allow the core some privacy for backchannelling."