Impact of on-topic and off-topic discussions on member participation and contribution in a common-identity online community

This study investigates the effects of various discussion topics on individuals’ decisions to join and contribute to an online community. Based on their relevancy to the community's interests and goals, we distinguish between on-topic (relevant) and off-topic (irrelevant) discussions. The relationships among group discussion, new member acquisition, and current member contribution are simultaneously modeled and estimated using data collected from a question-and-answer website. We employ a latent Dirichlet allocation model to identify different topics posted by community members. The relevancy of each topic is assessed based on relevancy scores collected through a survey. The results suggest that on-topic discussions generally increase the number of new and active members. Intriguingly, off-topic discussions can influence new member acquisition both positively and negatively, while their effect on current member contributions appears to be positive. The implications of this study for sustaining online communities are discussed.