UStwo...we can debate the merits of the two studies on another thread if you like.
Suffice it to say, numerous flaws in the methodology and conclusions of the Groseclose/Milyo study have been pointed out...starting with assigning scores to media outets based on the number of times the outlet refers to think tanks and policy groups. There are a number of reasons why a media outlet would refer to a particular think tank/policy group that dont have anything to do with bias...the most obvious being the expertise of the group.
Just one example: if a media outlet referred to the NAACP on a story about race ,it would get a score that would identify it to the "left" because the NAACP is "liberal". No matter that the NAACP is often reffered to in many outlets because of its recognized history and leadership on issues regarding race. (I made the example a bit more simplistic than the actual practices in the study, but it gets at the core problem.)
I wont bore others here with more.