Is there data or research on the tradeoffs associated with allowing anonymous posting on forums like Piazza?
I have used Piazza in many mathematics courses. I can say, anecdotally but confidently, that students LOVE the anonymity option. Not everyone uses it, but I have had plenty of them tell me, either in person or (anonymously!) on course evaluations, that they appreciate the option since they can ask a seemingly "dumb" question without fear of appearing ignorant or uninformed. Perhaps this is particularly relevant in mathematics, where anxiety and performance-based fear is, alas, quite normal, but I'd imagine students in other disciplines would make similar comments.