How Hacker News ranking really works: scoring, controversy, and penalties
Controversy In order to prevent flamewars on Hacker News, articles with "too many" comments will get heavily penalized as "controversial". In the published code, the contro-factor function kicks in for any post with more than 20 comments and more comments than upvotes. Such an article is scaled by (votes/comments)^2. However, the actual formula is different - it is active for any post with more comments than upvotes and at least 40 comments. Based on empirical data, I suspect the exponent is 3, rather than 2 but haven't proven this. The controversy penalty can have a sudden and catastrophic effect on an article's ranking, causing an article to be ranked highly one minute and vanish when it hits 40 comments. If you've wondered why a popular article suddenly vanishes from the front page, controversy is a likely cause. For example, Why the Chromebook pundits are out of touch with reality dropped from #5 to #22 the moment it hit 40 comments, and Show HN: Get your health records from any doctor' was at #17 but vanished from the top 60 entirely on hitting 40 comments.
Nice analysis! You should check for stories that involve YC companies and/or their competitors. I've often thought that HN gives unfair advantage to stories about YC companies, beyond just the normal echo-chamber effect.
