Virtually all of us who identify ourselves as libertarians or conservatives (I’m the former) have believed, for as long as we have been paying attention, that the mainstream media, whether print or electronic, have a left-wing bias. The late columnist Edith Efron, in her 1971 book The News Twisters, documented that bias among the three major television networks of the time–ABC, CBS, and NBC. Now, University of California, Los Angeles political scientist Tim Groseclose has actually measured the bias, not just of the three traditional networks, but also their present-day network competitors and major newspapers.

Most of his findings will probably not surprise most readers of this publication. Groseclose concludes that, indeed, the mainstream media do tilt left. Why then do I review a book that tells us what we already “know”? There are four reasons: First, most of us don’t know it to the extent Groseclose knows it–his argument is an empirical tour de force. Second, he is so numerate that he makes clear with the data just how extreme the left-wing bias is. Third, there are some surprises in the data, particularly about the Fox News Channel and the Wall Street Journal. Fourth and finally, Groseclose shows that the biased information people get causes them to vote to the left of their true positions.

This is from my review of Tim Groseclose’s Left Turn: How Liberal Media Bias Distorts the American Mind. The review appears in the current issue of Regulation. Some further excerpts:

The bias shouldn’t be surprising given the political views of reporters. Surveys show that Washington correspondents vote for the Democratic candidate at a rate of 85 percent or more, Groseclose notes. Studies of contributions to presidential campaigns have found that more than 90 percent, and as many as 98.9 percent, of journalists who contribute to a presidential campaign give to the Democratic candidate. These overwhelming numbers mean, Groseclose says, that residents of left-wing academic communities like Cambridge, Mass. and Berkeley, Calif. are, on average, much more conservative than Washington media correspondents.

Groseclose examines a few issues to show the bias at work. The first item he discusses is a Los Angeles Times article on the number of black students at UCLA. Groseclose dissects the story to show that the reporter, Rebecca Trounson, presents the data and reports interviews in a biased way. For instance, to buttress her case that the UCLA admissions process discriminates against black people, she cites six people, five of whom are on the political left, and only one of whom is conservative. Moreover, she pulls a favorite trick of left-wing reporters: identifying the ideology only of the conservative. Trounson’s L.A. Times colleague, Ralph Vartabedian pulled the same trick on me–although, unlike Vartabedian, Trounson at least got the ideology right. (Vartabedian described me as a conservative. See my August 18, 2010 blog post, “Media Bias and the L.A. Times” for more.)

I should note that the UCLA admissions process is racist. As Groseclose notes, UCLA discriminates, probably illegally, in favor of black applicants. One problem he identifies with Trounson’s approach is that she missed the big story: the rising percentage of Asians at UCLA and the falling percentage of whites.

And finally:

In an interview with the Hoover Institution’s Peter Robinson, Groseclose explained it another way: Currently, the average U.S. voter has the same political quotient as the average Iowa voter. But with no media bias, the average U.S. voter would, instead, be like the average voter in Kentucky or Texas.

I do have one criticism, early in the review, of Groseclose’s misstating an important bill before Congress and a couple of criticisms at the end. But the bottom line is that Left Turn is an outstanding book.