<p>I'd like to rank my stories based on "controversy" quotient. For example, reddit.com currently has "controversial" section: <a href="http://www.reddit.com/controversial/" rel="nofollow noreferrer">http://www.reddit.com/controversial/</a></p>

<p>When a story has a lot of up and a lot of down votes, it's controversial even though the total score is 0 (for example). How should I calculate this quotient score so that when there's a lot of people voting up and down, I can capture this somehow.</p>

<p>Thanks!!!</p>

<p>Nick</p>

The easiest method is to count the number of upvote/downvote pairings for a given comment within the timeframe (e.g. 1 week, 48 hours etc), and have comments with the most parings appear first.  Anything more complex requires trial-and-error or experimentation on the best algorithm - as always, it varies on the content of the site and how you want it weighted.
Overall, it's not much different than a hotness algorithm, which works by detecting the most upvotes or views within a timeframe.