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Thoughts on Groseclose book on media bias

Respected political scientist Tim Groseclose just came out with a book, “Left Turn: How Liberal Media Bias Distorts the American Mind.” I was familiar with Groseclose’s article (with Jeffrey Milyo) on media bias that came out several years ago–it was an interesting study but I was not convinced by its central claim that they were measuring an absolute level of bias–and then recently heard about this new book in the context of some intemperate things Groseclose said in a interview on the conservative Fox TV network.

Groseclose’s big conclusion is that in the absence of media bias, the average American voter would be positioned at around 25 on a 0-100 scale, where 0 is a right-wing Republican and 100 is a left-wing Democrat. (Seeing as the number line is conventionally drawn from left to right, I think it would make more sense for 0 to represent the left and 100 to be on the right, but I guess it’s too late for him to change now.) Groseclose places the average voter now at around 50, so, by his assessment, media bias is a huge deal.

After some further blog discussion, I became curious enough to head over to the local Barnes & Noble and take a look at the book.

Before I get to the details, let me again link to Brendan Nyhan’s thorough methodological discussion of the Groseclose and Milyo article from 2004.

Journalism as one of many institutions that affect politics

Stepping away from the data for a moment, it makes sense that the news media would generally fall on the left side of the political spectrum. Whether this is good or bad is another question, but newspapers generally seem to position themselves on the side of the underdog. Consider, for example, the slogan that a newspaper should “comfort the afflicted and afflict the comfortable.”

Another way to think about media bias is to think about the communication industry as a whole. I imagine that “journalism,” taken as a whole, leans left, while “public relations,” taken as a whole, leans right.

And if most of the news media in a country moved from journalism to public relations (as in Berlusconi’s Italy), I could imagine it could make a difference in the country’s politics.

The question, “What would public opinion be like if journalists expressed views comparable to the average American?”, while interesting, could perhaps be combined with similar questions such as, What would U.S. politics be like if there were no public relations industry? Or, What would U.S. politics be like if campaign contributions were given equally to the left and the right? Or even, What would U.S. politics be like if religious leaders were, on average, in the political center?

My point is: Thinking of all the different institutions affecting political attitudes, it makes sense a priori to suppose that journalism in particular is on the left. Traditionally, journalism and universities have been on the left, and business and religion have been on the right. There are lots of exceptions, from Martin Luther King to Silvio Berlusconi, but my first guess would be that journalism is one of the left-leaning institutions in the U.S.

It makes sense for Groseclose, as a conservative media analyst, to want to shift journalism to the right, just as, from the other direction, a liberal businessman might want to persuade businesses to move in the other direction.


Policy and politics are multidimensional. For example, Slate magazine notoriously polled its staff a few years ago and found 55 out of 57 supporting Obama. On the other hand, a Slate writer (who I’d guess is an Obama supporter) wrote this:

If we can find other ways of overcoming the simmering resentment that naturally accompanies wage cuts, workers themselves will be better for it in the long run.

The “we” at the beginning of the sentence does not seem to be the same as the “workers” at the end of the sentence. This is just an anecdote (n=1, and not a randomly sampled n=1 at that) but I do think it reflects a general attitude in the big media, to by default take the perspective of the employer or rich person rather than the employee or lower-income person. (Think of all those famously obnoxious NYT or WSJ lifestyle pieces.)

The multidimensionality of political attitudes should not discourage us from studying bias but it’s worth keeping in mind.

In the U.S. context I think there’s asymmetry in political bias, with Democratic reporters–a survey a few years ago found that twice as many journalists identify as Democrats than as Republicans–biasing their reporting by choosing which topics to focus on, and Republican news organizations (notably Fox News and other Murdoch organizations) biasing in the other direction by flat-out attacks.

I’ve never been clear on which sort of bias is more effective. On one hand, Fox can create a media buzz out of nothing at all; on the other hand, perhaps there’s something more insidious about objective news organizations indirectly creating bias by their choice of what to report.

But I’ve long thought that this asymmetry should inform how media bias is studied.

What is media bias?

Before getting to measures of media bias, let’s think of some ways that a news organization could be politically biased:

– Reporting that the unemployment rate today is twice as high as it was during Bush’s presidency . . . or reporting that it doubled during the two years leading up to July 2009 and has slightly declined since then.

– Reporting economic news more frequently when the economy is improving with one party in power or declining when the other party is in power. (See here and here.)

– Reporting on the sex scandals of David Vitter and Newt Gingrich . . . or reporting on the sex scandals of Anthony Weiner and Al Gore.

– Interviewing an attractive person who’s out of a job and has no health insurance . . . or interviewing an attractive person who had to shut down a business because of high taxes.

– Running a warm-and-fuzzy human interest story about an up-and-coming conservative Republican politician . . . or running that same story about a liberal Democrat.

– A clip of a cute same-sex couple getting married . . . or footage of scary-looking people at a gay pride parade.

– A feature on tax-subsidized corporate jets . . . or on the big salaries paid to union bigwigs.

Linking John McCain to an official bio while linking Barack Obama to mocking cartoons . . . or vice-versa.

– Coverage of political rallies etc.

– Giving Democrats or Republicans, or liberals and conservatives, opportunities to address the audience directly in op-eds, softball interviews, etc.

– Flat-out endorsements.

– Using politically-loaded terms such as “Star Wars” for the missile-defense program or “death tax” for the estate tax.

Some of these biases have been studied. For example, a Media Matters report found that the Sunday talk shows (Meet the Press, etc) had more Republican than Democratic panelists in the 1997-2005 period.

And Gentzkow and Shapiro implemented a generalization of Groseclose and Milyo’s method to evaluate what they call the “slant” of different newspapers based on how often they use phrases that distinguish the two parties (for example, Republicans talkes about “personal accounts” for Social Security, while Democrats used the term “private account”).

An indirect measure of bias

Setting aside the methodological criticisms raised by Nyhan and others, my big problem with the Groseclose and Milyo estimates of media bias is that they are indirect.

Consider first some simple, direct measures of bias: Counting how many Democrats and Republicans, or liberals and conservatives, appear on op-ed pages or TV interviews. Tabulating the frequency of political sales terms such as “death tax” or “Operation Freedom” or “Affordable Care Act” (as compared to “estate tax” or “Iraq war” or “the Obama health care plan”). Measuring the prominence of positive or negative economic stories (is the bad news always on page 1 and the good news on page 14?).

With some thought we could probably come up with more. My point is that all the above are direct measures of bias. If you do more of X and less of Y, you’re biasing the news in one direction or another–you’re directly sending out a message that can influence people.

In contrast, the Groseclose and Milyo measure–citations of research and advocacy groups–is almost entirely indirect. Sure, if you quote the Family Research Council, you’re likely to be making a conservative point (or providing the conservative perspective in a he-said, she-said story). But it’s not directly an influence; rather, it’s indicative that the news organization might be taking the side of this source.

Here’s another example: the Poole and Rosenthal measures of legislators’ positions. You can argue about their methods, but their estimates are ultimately based on votes in Congress. The way a congressmember gets placed on the left or the right is by voting on the left or right in actual votes. Similarly with various ideal-point estimates on the Supreme Court. The methods aren’t perfect but, again, they’re based on actual votes. Or Bafumi and Herron’s estimates (featured in Red State Blue State) that most voters are less extreme on the issues, compared to congressmembers. These positions are based on how survey respondents say they would have voted on particular issues. You get placed to the left or the right based on actual political positions.

The Groseclose and Milyo estimates aren’t like that. This is not to say they’re definitely wrong, just that any interpretation of them is inherently much more fragile than various more direct measures of bias in communication.

From bias to political outcomes

Groseclose’s model takes several steps:

1. From different rates of mentions of research and advocacy groups, to relative measures of political position of media organizations.

2. From relative to absolute positions: thus, it’s not that Fox News is to the right of CNN, it’s that Fox is near the center and CNN is biased to the left.

3. From absolute positions to the effects of hypothetical changes (for example, how would Americans vote if all their news media had the political slant of Fox News?).

4. From effects of changes in the media environment to the inference about the Americans’ true political positions that they would have if the media reflected their views.

In Groseclose’s endgame, a balanced media might include some TV networks promoting the view that abortion should be illegal under all circumstances and subject to criminal penalties, whereas others might merely hold that Roe v. Wade is unconstitutional; some media outlets might support outright discrimination against gays whereas others might be neutral on civil unions but oppose gay marriage; and on general politics there might be some newspapers that endorse hard-right Republican candidates (0 on Groseclose’s 0-100 scale) whereas those on the left would endorse the positions of Senator Olympia Snowe).

I don’t have much to say about steps 3 and 4 above; as noted earlier, I find it plausible that a Berlusconi-style media environment could shift U.S. politics far to the right, but given the effort it would take to maintain such a system (in Italy, Berlusconi has the power of the government but still has continual struggles with the law), it’s hard for me to think of this as an equilibrium in the way that it is envisioned by Groseclose. This just seems like a counterfactual that would require resources far beyond what was spent to set up Fox News, the Weekly Standard, and other right-leaning media properties.

It is more difficult for me to evaluate Groseclose’s steps 1 and 2. For the reasons expressed by Brendan Nyhan, I am skeptical about the steps used to get the estimates, and for the reasons given above, I worry that the estimates are so indirect that if anything goes wrong in the model, there is no reason to believe them at all. On the other hand, it seems completely plausible that the news media lean left on many issues. I think the most useful approach might be to consider positions on an issue-by-issue basis.


  1. Steve Sailer says:

    Groseclose's methodology privileges causes that have enough money behind them to have their own thinktanks. I'm more interested in the ideas that are in the general public's interest but not any deep-pocketed special interest's. Those have a hard time getting heard.

  2. Corbett says:

    Those ‘Thoughts on Groseclose’ distill down to :

    ” I was not convinced by {Grosclose’s} central claim that they were measuring an absolute level of bias

    … it makes sense that the news media would generally fall on the left side of the political spectrum.

    My point is… it makes sense a priori to suppose that journalism in particular is on the left.

    … my big problem with the Groseclose and Milyo estimates of media bias is that they are indirect… This is not to say they’re definitely wrong. I worry that …. if anything goes wrong in the model, there is no reason to believe them at all. “


    So you basically agree that the “news media” & “journalism are politically left, but quibble that Groseclose has not absolutely and definitively measured that reality to your satisfaction (??)

  3. andrewgelman says:


    If Groseclose or anyone else wants to say that journalists are mostly Democrats, that's fine. If you want to say that your claim of an absolute bias is backed up by statistical evidence, then it's hardly a quibble to consider what your evidence is.

    Groseclose's contribution in his book is not merely to state that journalists are mostly on the left. Lots of people are writing books about that. Groseclose's contribution is his quantitative model and evidence, and that's what I'm addressing.

  4. kdk says:

    Has anyone written anything assessing why journalists skew Democratic? Selection into field? Experiences after choosing the profession? Editorial discretion? Urban location? Do we have a measure of skew by party over time?

    Also, it seems obvious to me that it's better to be in a 25% minority, since then one is guaranteed to become the majority…