Results of a study by Disqus on commenter quality, circa 2012, where "quality" is based on an aggregate of likes, replies, flags, spam reports, and comment deletions.  (Note that the original graph is erroneous and does not have the correct bar lengths.)  https://web.archive.org/web/20130923094305/http://disqus.com/research/pseudonyms/
Own work
Omegatron