The Ruby ecosystem has very strong emphasis on tests and test driven development. Perhaps bugs in Ruby simply often are fixed before they're committed because t

The Ruby ecosystem has very strong emphasis on tests and test driven development. Perhaps bugs in Ruby simply often are fixed before they're committed because the test suites have better coverage. Also I think Ruby developers are more likely to be professional (as in paid and educated to be programmers), whereas python developers might (slightly more) often be mathematicians, scientists or sysadmins. As is noted in the paper, all other factors that were controlled for were strongly dominant. That means who you are and what you are doing is much more important than what language you do it in.