Winning the Media Campaign 2012 | Project for Excellence in Journalism (PEJ)
"The study also reveals the degree to which the two cable channels that have built themselves around ideological programming, MSNBC and Fox, stand out from other mainstream media outlets. And MSNBC stands out the most. On that channel, 71% of the segments studied about Romney were negative in nature, compared with just 3% that were positive-a ratio of roughly 23-to-1. On Fox, 46% of the segments about Obama were negative, compared with 6% that were positive-a ratio of about 8-to-1 negative.
These made them unusual among channels or outlets that identified themselves as news organizations."
(The "normal" ratio is 2-to-1 negative.)