OMG: brains can’t handle all our Facebook friends. The size of social networks. Ross Mayfield's Weblog: Augmenting your Dunbar Number. The the latest issue of First Monday has an interesting study by Bernardo Huberman and other researchers at HP's Social Computing Lab on Social Networks that Matter: Twitter Under the Microscope.
Among other things, it reveals a hidden network of relationships underpins those declared in our use of Twitter: In conclusion, even when using a very weak definition of “friend” (i.e., anyone who a user has directed a post to at least twice) we find that Twitter users have a very small number of friends compared to the number of followers and followees they declare. This implies the existence of two different networks: a very dense one made up of followers and followees, and a sparser and simpler network of actual friends.
Life With Alacrity: Community by the Numbers, Part One: Group Th. We often think of communities as organic creatures, which come into existence and grow on their own.
However, the truth is they are fragile blossoms. Although many communities surely germinate and bloom on their own, purposefully creating communities can take a tremendous amount of hard work, and one factor their success ultimately depends upon is their numbers. If a community is too small you'll often have insufficient critical mass to sustain it.
Conversely, if it's too large you can end up with a community that's too noisy, too cliquey, or otherwise problematic.