Re:many short responses = LEAST helpful (Score 1)

Here is a short comment: The summary, which you did read, uses the word brief. The research paper (which you might not have actually read) does not measure comment length. It does measure # of messages in threads, and whether a person replies to others or initiates, as well as patterns in network ties. Those attributes predict answering behavior. But you bring up a good point. The length of a post does not necessarily have anything to do with its quality or insightfullness.