Results show that the variable that best predicts the chances of a community to survive is its level of heterogeneity: the greater the member turnover, the higher the chances that the group will sustain itself over time. On the other hand, the number of members and the number of actual message posters do not predict the chances of survival.
According to the current study, another reliable predictor is the number of messages that are posted between members of an online community.
via physorg.com