Small negative correlation: http://www.journals.uchicago.edu/doi/abs/10.1086/603536 http://www.journals.uchicago.edu/doi/abs/10.1086/603536 (I have the full te

Small negative correlation: http://www.journals.uchicago.edu/doi/abs/10.1086/603536 http://www.journals.uchicago.edu/doi/abs/10.1086/603536 (I have the full text of the paper, but I've not actually read it.)