I don't anything about the methodologies etc but I liked the quote so-
"Of the LAMP stack, Perl had the best defect density well passed standard deviation and better than the average," Chelf said.
Perl had a defect density of only 0.186. In comparison Python had a defect density of 0.372 and PHP was actually above both the baseline and LAMP averages at 0.474.
Other popular projects included in the 32 projects that made up the baseline are: Firefox (0.355), Gaim (0.352), Gnome (0.458), GCC (0.202) and Samba (0.695), among others.
Now I can say Python is twice as buggy as Perl. And I know it's true because I read it on the Interwebs.