The chart was derived from a survey I did of 200 randomly-chosen biographies.
Think about this: there are roughly 1 million bios on English WP.
If about 1.5% of them are defamatory, that's 15,000 people being defamed.Stubs, you say? Let me tell you about stubs on Wikipedia.
(IMG:
http://i583.photobucket.com/albums/ss273/metasonix/articlelengthpiechart.png)