Expert pollster John Zogby is "95 percent certain" that around 650,000 Iraqis civilians have died since the U.S. invasion of Iraq in 2003. A new study by Iraqi physicians and Americans from Johns Hopkins University polled 1,800 Iraqis to calculate an approximate number of casualties since the beginning of the war.

In an interview on CNN International, Zogby explains that the methodology used in the study is very reliable. "The methodology, from what I've seen of the survey, is quite good," he remarked. He is also in agreement with the study's estimate of 650,000 casualties, saying, "I can't vouch for it 100 percent, but I'll vouch for it 95 percent, which is as good as it gets in survey research."

At a press conference earlier in the day, President Bush said that he did not agree with the study's results, saying, "I think that methodology has been pretty well discredited."TRANSCRIPT

VASSILEVA: Well, that figure is some 655,000 Iraqis. That's far greater than any number we've heard so far.

HOLMES: Yes, multiples higher. That's right. Back in December, U.S. President Bush, for example, estimated about 30,000 Iraqi civilians had lost their lives. That's about 20 times lower than the deaths cited in this report.

VASSILEVA: A private Iraq body count group estimated the number of civilian deaths falls between about 44,000 and 49,000. It bases its statistics on media and eyewitness accounts.

HOLMES: All right. We are joined now from our Washington bureau by John Zogby. He's president and CEO of Zogby International, that conducts political polls in the U.S., as well as opinion polls in Iraq.

And thanks for your time.

You do this for a living. Why such a massive increase in the numbers in the numbers? Is the methodology good?

JOHN ZOGBY, ZOGBY INTERNATIONAL: The methodology of the survey, I think, from what I've seen so far is quite good, following all the rules of random sampling to a degree that it's possible in a country like Iraq, and cluster sampling. zeroing in on sampling points that are representative.

I think where some of the disconnect may very well be is that this was indeed according to the methodology statement that I read a nationwide survey, including clusters of areas that are not within the daily purview of where the media are and where many public officials are who report those body counts.

And so, I mean, translated, the media clustered in about five or six cities, and that's where much of the body count comes from. There is so much more to Iraq than just five or six cities.

HOLMES: You make a really good point. I've been there many times, and as recently as last month. When we were there then, we were talking about these numbers, and how rubbery, if you like, they are. The U.S. would say numbers are down, and then you'd find out they weren't counting car bomb victims. And as you say, the Baghdad morgue is perhaps the biggest source of death tolls, but it's just one morgue. And a lot of people aren't taken to that morgue. Do you think that this could really be an accurate figure?

ZOGBY: I can't vouch for it 100 percent, but I'll vouch for it 95 percent, which is as good as it gets in survey research. I know PIPA, the group at the university that conducted the polling in the U.S. I know of the group that -- the university that published and conducted the survey on the Iraq side. In fact, we've used them ourselves. These are good researchers. I have read their methodology statement. It is a good one and a sound one.

I don't know the specific questions they asked. One of the things I'd like to know is, above and beyond the count, where they place blame, where the public places blame for the deaths. That can get a little squidgy, in the sense that you're going to get a lot more people blaming allied forces, blaming America than might be directly involved in the killings.

But in terms of the sampling of methodology that was used, this is sound and this is going to generate quite a bit of debate.

I don't think that there's anybody in my business who responsibly believes that 30,000 to 40,000 or 45,000 Iraqis have been killed since March of 2003.

HOLMES: Right. That was always a nonsense figure. I mean, you just needed to do the math day to day with 100 people being found in the streets some days.

ZOGBY: Excuse me, Michael. But 100 people found in Baghdad, or Mosul or Al Ramadi (ph).

HOLMES: Yes, absolutely. Actually normally just in Baghdad. And there are a couple of areas in Iraq that are far more violent than Baghdad itself, believe it or not.

Just finally, John, do you think this group being fairly reputable. The number I saw being criticized. The number of the sampling, I think was 1800 people, but that's a decent-sized sample. We recorded our own CNN poll today there was only 1,000 people.

ZOGBY: And CNN, and my company are others are able to call U.S. elections and European elections with pinpoint precision using a sample of a thousand; 1,800-plus sample in a country like Iraq is more than enough to do the job and to get the ballpark figure that they got here.

HOLMES: Right. Very, very important coming from you, John. Appreciate that. John Zogby of Zogby International. A lot of criticism over this report already from the White House, saying it's not credible. But as you say, there's a lot there to be taken very seriously.

Thanks, John.

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