Monday, September 20, 2004

Gallup poll biased toward Bush?

In case you're spending all your time on right-leaning blogs, be aware that the left-leaning blogs are saying that the recent Gallup poll—which showed Bush leading by 13% among likely voters—is biased toward Bush.

...Gallup oversamples greatly for the GOP [40% of sample], and undersamples for the Democrats [33% of sample]. Worse yet, Gallup just confirmed for me that this is the same sampling methodology they have been using this whole election season, for all their national and state polls.

If Gallup's sampling methodology is consistent over time, then Gallup is showing a real Bump for Bush, regardless of whether the underlying sampling is accurate. (Gallup had Bush with a 7% edge in likely voters immediately following the Republican convention.) But it is unclear what the real numbers are.

And it is far too soon for Bush supporters to get cocky. The Washington Times reports that three other polls are showing the two candidates within a percent of each other among likely voters.

Update: Turns out weighting by party ID may be a bad idea. See Mystery Pollster and Kausfiles for more details.

Update: Chris Graham of The Augusta (Va) Free Press (which carries the tagline, "Our only agenda is the truth") is reporting,
And then you have to factor in Fox News, which makes no secret of its bias, and which was saying a couple of weeks ago that the election was too close to call, according to its own polls. [Emphasis added.]
Mr. Graham, please let me know where Fox News has acknowledged an organizational bias in the election. This is a major scoop if you can find it.