A study doesn’t actually compare the nature of negativity – "McCain’s out of touch" is not regarded as anything different than "Obama’s an enemy of the troops" – but simply codes ads as positive, negative and contrast ads (both negative and positive). The bottom line:
Looking at the tone of all of McCain’s advertising from June 4 to October 4, we found that 47 percent of the McCain spots were negative (completely focused on Obama), 26 percent were positive (completely focusing on his own personal story or on his issues or proposals) and 27 percent were contrast ads (a mix of positive and negative messages). What about Obama? Our analysis reveals that 39 percent of all general election Obama TV ads have been positive (solely about his record, positions or personal story), 35 percent have been negative (solely focused on McCain) and 25 percent have been contrast ads – mixing a bit of both. So, on a proportional basis, the McCain campaign is and has been more negative than Obama.
Then the study tries to say that because of the volume of Obama’s ads, it’s a draw. No way.
The Dish 