kelticwizard wrote:With Rasmussen an obvious property of the Republican party since 2000, this year's GOP hireling is the Gallup organization. With no evidence whatsoever, Gallup has decided that the electorate this year will consist of 40% Republicans and 33% Democrats, and that their polls will be arranged to reflect that notion. So any Gallup poll has a built-in 7% slant towards Bush, any way you look at it.
The "evidence" the Gallup poll bases its numbers on is, quite simply, the number of Republicans and Democrats they encounter in their likely voter sample. No more and no less. The striking (and controversial) point about their polls is namely that, unlike other pollsters, they do
not "arrange" their numbers to meet certain proportions of party ID. That's what they're being criticized for.
Two points to make here. One: a number of polls (Zogby, TIPP, the ABC/WaPo tracking polls) weight the results they get from their polling sample by party ID. Eg, if they pull in a sample of 1000 that includes 400 Republicans and only 300 Democrats when, back in 2000, Dems and Reps each represent about a third of the voters according to the exit polls, they will weight these numbers to make them conform to those 2000 proportions. That is, they'll give each of those 400 Republicans less weight than each of the 300 Democrats, so in the end both subsets weigh in on the final result roughly the way they did in 2000.
Gallup does not do this. Gallup does not believe in weighting by party ID. And there is a good case to be made against such weighting: after all, it assumes the proportions of self-described Democrats and Republicans in the electorate will be the same this year as last time. This got pollsters in a lot of trouble in 2002, when suddenly a lot more Republicans turned up at the polls - or a lot more voters at the polls described themselves as Republicans - than past record would have suggested.
So in response to your post the point here is that Gallup has not "decided" that the electorate consists of 40% Republicans. In fact, it is one of the pollsters that does
not add a decision of their own on what proportion of party IDs can realistically be expected to turn up at the vote into the mix when calculating likely voter results. If they got 40% Republicans, its because thats what they happened to find in their likely voter sample.
Which brings us to the next question and a more reasonable explanation of why Gallup has polled so Republican-favourable this year: what is up with their likely voter sample, if it yields such counterinstinctually high proportions of Republicans?
First off, it needs to be said in re: to your post, that of all pollsters, Gallup has by far been the most open and transparent about its methodology. Mystery Pollster (a Democratic analyst, by the way)
writes:
Quote:We are able to nitpick their model largely because Gallup has been extraordinarily open about their internal procedures, more so than other pollsters. They have patiently answered questions from the most critical of outsiders. They routinely turn their raw data over to the Roper Center after each election, where academics can scrutinize their methods and search for flaws. That Gallup has been punished, in effect, for its openness has not been lost on competitors who remain considerably less forthcoming. So while it is appropriate to question Gallup's model, we ought to give them credit for their transparency. By opening themselves up to criticism this way, they are advancing the art and science of survey research.
In the same post, Mystery Pollster provides an
excellent summary of what their methodology actually is, so no reason for me to repeat. After a
follow-up post summarising some main points of critique levelled at it, he then
explains the main problem. He doublechecks the assertion that Gallup has come up with strikingly Bush-friendly numbers this year (it has), and then analyses what the reason behind it could be. No, its not that Gallup has been "bought" by the Republicans. But the Gallup poll might well be "simply screening out too many voters who do not typically vote in presidential elections". First-time voters, for example. Self-reported first-time voters were just 6% of the Gallup poll's likely voter sample, while they constituted 9-10% of the LV sample in rival polls - and of the turnout in 2000. And if anything, their proportion now should be even higher than in 2000. This is significant because both opinion polls now and the 2000 results suggest that the Democratic candidate enjoys a huge advantage among first-time voters, netting a 10-20% lead among them.
Basically, the Gallup poll is so rigorous in its elaborate system of weeding out likely voters, that it appears to risk grossly overreporting the ever-reliable, ever-informed voters, and underrepresenting the less sure-footed ones. In turn this has led it to underreport the low-income and minority vote - Gallup LV samples have had fewer blacks and hispanics than other pollsters'. Other polls, like Fox and DemCorps, would have compensated such discrepancies a little still by their application of regional weightings, to make the sample reflect the regional turnout numbers from the previous election. But Gallup does not apply those either.
The difference between Gallup and other polls shows up so conspicuously this time because this year's elections involve such an increased interest among new and irregular voters. This has made other polls stretch up their classification of likely voters, encompassing a greater share of registered voters than normally. A NYTimes poll for FL released today for example (see Daly) defined 96% of registered voters as "likely to vote". That would be a huge turnout. And there's the rub, because Gallup does apply the one weighting: on turnout. They recalculate their LV sample as much as they need to to make it reflect a 55% turnout. So while other polls have increased their definition of who is likely to vote on the basis of the answers they got, Gallup kept counting only the 55% of respondents who best fit their criteria of being likely to vote. Excluding those new or irregular voters that boost Kerry's numbers in other polls.
Gallup has listened to the criticisms and will apparently raise their cutoff for likely voters on their last survey, coming up this weekend, to 60%. Let's see if that will indeed show up a different proportion of Reps and Dems, and what effect that in turn will have on their horserace numbers ...
In a final link, this is MysteryPollster's
uncharacteristically impassioned response, as one Democrat to another, to the MoveOn anti-Gallup ads.