How Is It Different Polls Produce Different Results?
LINDA WERTHEIMER, Host:
Let me just begin by asking you to look at a couple of polls from last week. There's a Rasmussen poll that shows Republicans are leading, nationally, by about three points, and a Gallup poll that in one scenario has Republicans leading by 18 points. Now, why would you have a difference like that?
MARK BLUMENTHAL: So, we know from many of years of studies that the true likely electorate is going to be a lot older, better educated. It's going to be a little more affluent. It's going to be less-minority and a little more rural than the larger pool of registered voters. And so all pollsters are trying to give that larger sample a nudge toward the demographics of the likely electorate.
WERTHEIMER: Well, let's talk a little bit more about that likely voter, because a likely voter is not exactly the same as a registered voter. It seems to be that people generally tell pollsters that they're going to vote because that's the right thing to say.
BLUMENTHAL: That's right.
WERTHEIMER: So what does the likely voter look like?
BLUMENTHAL: The best they can do is say we know this is sort of a picture of the most likely electorate and this is a picture of a much wider than likely electorate, and we know that the truth is somewhere in between.
WERTHEIMER: Well here's another evaluation question. You're looking at a poll. It was done by a Democratic candidate. Do you think that's a reliable poll?
BLUMENTHAL: So we do find when we look at all of the polls released by campaigns that the ones by Democrats tend to be a few points better for the Democrats, on average, and vice versa.
WERTHEIMER: Do you have any lurking fears in your heart that somehow this thing could just get completely blown up? I mean I know it's not the same thing, but there was the year when the exit polls were horribly wrong.
BLUMENTHAL: I think every pollster worries about that, but I think that we might reassure ourselves, for the last ten to fifteen years they've been pretty good and they've been pretty good in general elections. Primaries have been more difficult. The intellectually honest thing to do is to be open to that possibility, but within reason.
WERTHEIMER: I can't possibly do without them, so I certainly hope you're right.
BLUMENTHAL: Alright, well we're glad to hear that.
WERTHEIMER: Mark Blumenthal of the Huffington Post. He's also the co-founder of pollster.com. Thank you very much for coming in.
BLUMENTHAL: Thank you for having me.
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