Although analyzing user behavior within individual communities is an active
and rich research domain, people usually interact with multiple communities
both on- and off-line. How do users act in such multi-community environments?
Although there are a host of intriguing aspects to this question, it has
received much less attention in the research community in comparison to the
intra-community case. In this paper, we examine three aspects of
multi-community engagement: the sequence of communities that users post to, the
language that users employ in those communities, and the feedback that users
receive, using longitudinal posting behavior on Reddit as our main data source,
and DBLP for auxiliary experiments. We also demonstrate the effectiveness of
features drawn from these aspects in predicting users' future level of
activity.
One might expect that a user's trajectory mimics the "settling-down" process
in real life: an initial exploration of sub-communities before settling down
into a few niches. However, we find that the users in our data continually post
in new communities; moreover, as time goes on, they post increasingly evenly
among a more diverse set of smaller communities. Interestingly, it seems that
users that eventually leave the community are "destined" to do so from the very
beginning, in the sense of showing significantly different "wandering" patterns
very early on in their trajectories; this finding has potentially important
design implications for community maintainers. Our multi-community perspective
also allows us to investigate the "situation vs. personality" debate from
language usage across different communities.

本文研究多社区交互的用户行为，从 Reddit 的长期发帖行为和 DBLP 的实验中，考察社区发帖顺序、语言使用和反馈对用户预测活性的影响，并探讨多社区环境下用户的行为特点，发现用户将更加多元化，且早期表现的 “漫游” 模式具有重要的设计意义。同时，利用不同社区的语言使用比较探讨了 “情境 vs. 个性” 的论点。