  Online forums are rich sources of information about user communication
activity over time. Finding temporal patterns in online forum communication
threads can advance our understanding of the dynamics of conversations. The
main challenge of temporal analysis in this context is the complexity of forum
data. There can be thousands of interacting users, who can be numerically
described in many different ways. Moreover, user characteristics can evolve
over time. We propose an approach that decouples temporal information about
users into sequences of user events and inter-event times. We develop a new
feature space to represent the event sequences as paths, and we model the
distribution of the inter-event times. We study over 30,000 users across four
Internet forums, and discover novel patterns in user communication. We find
that users tend to exhibit consistency over time. Furthermore, in our feature
space, we observe regions that represent unlikely user behaviors. Finally, we
show how to derive a numerical representation for each forum, and we then use
this representation to derive a novel clustering of multiple forums.
