The work on media bias and media markets by economists is really taking off. John Lott and Kevin Hassett’s paper Is Newspaper Coverage of Economic Events Politically Biased? finds that "American newspapers tend to give more positive news coverage to the same economic news when Democrats are in the Presidency than for Republicans."
Predictably, the research was trashed (read to the bottom), without argument, by some people who have a visceral reaction to the name John Lott. Those who take this position, however, have to contend with new research from different authors using different methods and different data that nevertheless find similar results.
Riccardo Puglisi, for example, is an LSE graduate student out on the market this year. One of his dissertation chapters is Being the New York Times: The Political Behaviour of a Newspaper. Here is the abstract:
I analyze a dataset of news from the New York Times, from 1946 to 1994. Controlling for the incumbent President’s activity across issues, I find that during the presidential campaign the New York Times gives more emphasis to topics that are owned by the Democratic party (civil rights, health care, labor and social welfare), when the incumbent president is a Republican. This is consistent with the hypothesis that the New York Times has a Democratic partisanship, with some watchdog aspects, in that it gives more emphasis to issues over which the (Republican) incumbent is weak. Moreover, out of the presidential campaign, there are more stories about Democratic topics when the incumbent president is a Democrat.