Ivan Carter makes an excellent observation in Media Studies — Including Yesterday's in LA Times, Have Major Flaw which appears at Daily Kos. Here's the start of it:
The study that was widely cited yesterday, and reported in the LA times, is inherently flawed.
It found that the media's coverage of Barack Obama was negatively slanted in comparison to that of John McCain. But to the extent the facts favor McCain, what the study concluded would not necessarily be true.
And to the extent the facts tend to support Obama, the study's conclusion of media bias against Obama (or in favor of McCain) would understate the bias that is in fact present. And, perhaps more importantly, the stronger the case in favor of Obama (and the weaker the actual case in favor of McCain) the more this would be so.
There is no unwritten rule of politics or sociology dictating that the objective facts, in the context of every single voting American's personal beliefs, were they to have perfect knowledge, must invariably favor both candidates equally.
In other words, just we should not expect coverage of Osama bin Laden to be 50% positive, so too it does not follow that the two major candidates will be equally truthful, equally coherent, equally sensible, equally gaffe-prone, and so on. Yet that is the baseline which media bias studies such as the LA Times's use.
Even with the 50/50 baseline they find that McCain gets a better press than Obama. But when you consider that facts have a liberal bias, that result is particularly striking.