For thread-level feedback, we use karma points of the discussion thread itself; for the user-level feedback, we compute each user's subreddit-dependent k-index (Jaech et al., 2015), defined similarly to the well-known hindex (Hirsch, 2005).
a user's k-index k j in subreddit j is the maximum integer k such that the user has at least k comments with karma greater than k in that subreddit.