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This is a RUSH transcript from "The O'Reilly Factor," August 5, 2011. This copy may not be in its final form and may be updated.

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JUAN WILLIAMS, GUEST HOST: In the "Factor Investigation" segment tonight: It's well known to the "Factor" audience that liberal bias runs wild in the mainstream media, but you don't hear a university professor admit it very often. Bill O'Reilly spoke this week with UCLA political science professor Dr. Tim Groseclose, author of the new book, "Left Turn: How Liberal Media Bias Distorts the American Mind."

(BEGIN VIDEOTAPE)

O'REILLY: So, Doctor, how do you explain to your predominantly liberal students that the media, in your opinion, is actively liberal? How do you explain that to them?

DR. TIM GROSECLOSE, UCLA PROFESSOR: Well, the main -- the main way is just you get the data. That's what my book does, is it's loads -- I gathered lots and lots of data; 20,000 observations of media content, quantifying this in the data, and then you do the statistical analysis. I show, yes, here's the -- here's the slant. Here's what it is. One other thing that I do. It sometimes helps convince students. I say, you know, look, there's polls of reporters. You ask Washington correspondents who you voted for last election, they will tell you 93 to 7, 93 percent for the Democrat. I ask my students, you know, how could it not be the liberal slant? You know, I know it doesn't prove things.

O'REILLY: But they'll say -- the reporters will say, "Well, yes, I may be liberal in my private life, but I don't let that bleed over."

GROSECLOSE: And that's a fair point. I'm sympathetic to journalists who say that. But that's the point of my book, is that I analyze the content of the media. I look at actually what they say. I'm looking up transcripts, newspapers and translate that into data, and this data shows that, yes, they are indeed liberal.

O'REILLY: How does that affect the general population who may not watch television news, may just floating around? How does the liberal media affect them?

GROSECLOSE: Well, all I know is that from the reviews I've done of academic studies, three of them are in my book. All of them are something like an experiment. And what they do is they show when you change the content of the media in a certain area. For instance, one experiment gave -- called up northern Virginia residents and Washington, D.C. Just before calling them, they would flip a coin, and if it's heads they would give them a subscription to Washington Times. If it's tails give them a subscription to The Washington Post. After two months they called them up and asked who they voted for. And it turns out The Washington Post subscribers indeed voted more liberally, about 3.8 percentage points higher than the Times subscribers. So this change in the content of the media really did affect how people vote.

O'REILLY: And that was not a voluntary thing. You just randomly sent them the newspapers. They didn't, you know, liberal...

GROSECLOSE: That's right. That's right.

O'REILLY: That's fascinating.

GROSECLOSE: They only told people who did not have either one. It was determined by a coin flip who would get which newspaper.

O'REILLY: Right, so, basically, what -- what the experiment did was it sent a certain amount of people a conservative newspaper and a certain amount of people a liberal newspaper, not knowing what their proclivities were, what their opinions were.

GROSECLOSE: Exactly. Exactly.

O'REILLY: And the ones who read the conservatives tended to be more conservative. The ones who read the liberal tended to be more liberal.

GROSECLOSE: Right.

O'REILLY: OK. That's good. Now, you had me in the book and Dennis Miller and Ben Stein under the banner of P.Q., political quotient. What is that?

GROSECLOSE: Right, right. So it's a device that I've constructed just to measure political views numerically. So the political quotient, basically, higher numbers are more liberal. So on this scale, Nancy Pelosi is about 100. Michele Bachmann, Jim DeMint are about a 0. By my estimate, 50 is perfectly centrist. That's the P.Q. of the average voter. And as you said, this was more kind of casual observation.

But I said by my observation, it looks like Bill O'Reilly, Dennis Miller, Ben Stein looked like about a 25, which, if I'm right, puts you the midpoint between perfectly centrist, which by the way, would be something like an Arlen Specter when he was a Republican. So midpoint between Arlen Specter and Michele Bachmann.

O'REILLY: OK. So basically you're saying that "The Factor" and me, we're -- tend to be a little bit more conservative traditional. But we're not in the ideological territory that a Nancy Pelosi or a Michele Bachmann would be in.

GROSECLOSE: Right. Right.

O'REILLY: The other media -- the other media would be in one of the other camps.

GROSECLOSE: Right. Exactly. And so that's -- your political quotient, personally, I would say your slant actually is not as far right on that, because you have liberal guests on sometimes.

O'REILLY: All the time. I mean, I'm an independent. I have always described myself as an independent looking for -- for solutions. Now, you're at UCLA, not known to be a bastion of conservative thought. I mean, this isn't Oral Roberts University out there. And you're presenting a point of view that pretty much goes up against the liberal doctrinaire viewpoint. They don't want you to be telling the world, "Hey, you know, the U.S. media, not really fair and balanced. They're tilting way to the left." They don't want that. Have you gotten any fallout?

GROSECLOSE: Well, some. Not as much from my colleagues. I have to say some people have said, you know, "You're brave to do this." And I have to admit I'm only a little bit brave. I had tenure when I did this. And after that...

O'REILLY: That always helps. Can I get tenure on TV? Is that possible? Tenure means you can't get fired, no matter how big a pinhead you are. You're in there, and they've got to pay you. And so you waited until you got tenured to do the study. That's pretty smart there, Professor.

GROSECLOSE: Thank you.

O'REILLY: Now, do your students give you any jazz on it?

GROSECLOSE: Not as much. You know, believe it or not, I don't teach the media that much. I teach Congress more. In this Congress class, actually, I don't even talk my about my views. The students can't even tell the views. It's more about, you know, the rules and procedures of Congress.

O'REILLY: Yes, but after this interview they're going to know. You're going to get some heat.

GROSECLOSE: They'll know.

O'REILLY: All right. The book is "Left Turn: How Liberal Media Bias Distorts the American Mind." And, Doctor, we really appreciate you taking the time tonight.

GROSECLOSE: Thanks, Bill.

(END VIDEOTAPE)

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