We considered 3 models of authority: (1) (emerging topic detection) ETD uniform (i.e., equal weight); (2) ETD PageRank; and (3) bellwether. For 1 and 2, we built a directed graph of user activity, using thread coparticipation to define edges. Each EIN post was text tokenized, POS-tagged, and had stop words removed. We use a time window t 0 5 days to aggregate messages terms and a decay parameter d0 60 days. We identified emerging terms using an energy threshold approach, where emerging is defined as any term where energy! k*m energy over the interval t, where k is some constant; we used k 0 1.3. Any term identified as emerging that occurs in the postsubject line is flagged as important. For the bellwether model, we algorithmically selected 80 and 90 authors from the year prior to the one under analysis and flagged threads as important when one of those bellwethers participated in it. We also conducted 1000 random trials of selecting subsets of 80 users to follow.