Looking for a paper topic (or a thesis topic)? Here's a Tor research area that needs more attention. The short version is: for various diversity metrics, how has the diversity of the Tor network changed over time? How robust is it to change or attack? These results can help us make better design decisions.
We'd love to work with you to help answer these questions. Read more here: https://blog.torproject.org/blog/research-problem-measuring-safety-tor-network --Roger