On this one occasion, a Left Turn is permitted on NLT. Tim Groseclose is the author of Left Turn: How Liberal Media Bias Distorts the American Mind. Scott Johnson contends that "it may be the book of the year."
Professor Groseclose measures media bias with social-scientific methods and concludes that: (i) all mainstream media outlets have a liberal bias, and (ii) while some supposedly conservative outlets--such as the Washington Times or Fox News Special Report--do lean right, their conservative bias is less than the liberal bias of most mainstream outlets.
None of this is new, of course, but Groseclose provides fresh evidence and methodology to support the obvious conclusion. Peter Robinson interviews the author here.