Dr. Tim Groseclose, a professor of political science and economics at UCLA, has spent years constructing precise, quantitative measures of the slant of media outlets. He does this by measuring the political content of news, as a way to measure the PQ, or "political quotient" of voters and politicians.

Among his conclusions are: (i) all mainstream media outlets have a liberal bias; and (ii) while some supposedly conservative outlets--such the Washington Times or Fox News' Special Report--do lean right, their conservative bias is less than the liberal bias of most...