| Prior research suggests that members' ongoing participation in a community is influenced by their psychological identification with it, the community's internal structural dynamics, and characteristics of the communication exchanged within the community. However, most of this research has focused on characteristics of the individual members and the community under consideration, taking the existence of the community as a given and giving little attention to the larger context in which the community resides.; This dissertation extends prior research by proposing an ecological perspective when studying community success, taking into account the ecological and relational context of individuals' interaction with an online community. Two empirical studies were conducted to test the impact of context on the ongoing interactions between individuals and communities. The first study develops a theory of online community ecology, focusing on the impact of competition created by other communities in the same niche. Analysis of a longitudinal sample of 241 Usenet newsgroups over 64 months implies that both internal characteristics and external context affect communities' capability to retain members. Specifically, competition---the extent to which a community shares content with other communities and the extent to which the community's members also participate in other communities---represents an external threat that leads to a lower likelihood of members to return in the following time period.; The second study builds on the first to explore the impact of contextual factors on individual members' ongoing participation decisions in online communities. Applying social exchange theory, we propose to treat individuals' interaction with online communities as a series of social exchanges. In addition to the ecological context, relational context, i.e., individuals' prior relationships with an online community, is also expected to shape the ways individuals make decisions about ongoing interaction with communities. A research model based on social exchange theory is proposed and tested, with participation data of 43,758 individuals in seven Usenet newsgroups. The results suggest that an individual's motivation, the prior exchange history with the online community, and the availability of other alternative communities all play a role in the individual's continuance decision. |
