Those who defend the sudden tilt toward the Republicans in registered voter samples as a real political trend and not any kind of sampling problem, like to point toward the post-9/11 period as an example of a recent shift in the party ID distribution. If it happened then, they say, why shouldn't we give full credence to the shift we're seeing now?

But there is a very serious problem with this logic. After 9/11, despite the immensity of the rally effect behind the president and his party, the shift in party ID toward the Republicans was substantially less than what we're seeing now. What polls showed then was not a shift toward a 4-5 point (or more) Republican advantage in party ID--like we're seeing in some current polls--but rather a simple reduction in the Democratic edge or at best parity. Moreover, even this modest shift took place over several months, rather than over several weeks, like the shifts we've seen in some recent polls. (Note: these Republican gains were given back in a year or two, so the Democrats this year have had their a party ID edge at about the same level they had in 2000 and early 2001.)

Given this, how believable is it that we would now be getting not a gradual reduction in the Democratic party ID advantage (as we did after 9/11) but a much more sudden, much larger shift in party ID to produce an actual Republican advantage of 4-5 points or more? Are we really to believe that the GOP convention was such an earthshaking event that it had a bigger effect on the underlying sentiments of the electorate than did 9/11 and Bush's six months of 80+ approval ratings in the post-9/11 period?

And this from a convention that poll data said was viewed with a distinct lack of enthusiasm by the public! According to the Gallup poll, Bush's acceptance speech, which the media fawned over so ostentatiously, was not rated any better by the public than was Kerry's--in fact, it received slightly worse ratings. Kerry's acceptance speech was rated excellent by 25 percent and good by 27 percent; Bush's was rated excellent by 22 percent and good by 27 percent.

In terms of whether the Republican convention made voters more or less likely to vote for Bush, there were almost as many saying the convention made them less likely to vote for Bush (38 percent) as said it made them more likely (41 percent).

That was actually quite a poor performance. The Democratic convention this year had a substantially better 44 percent more likely/30 percent less likely split. In fact, looking back to 1984, which is as far back as Gallup supplies data, no candidate has ever had a more likely to vote for/less likely to vote for split even close to as bad as Bush's this year.

Well, what about the tone of the convention? Did voters think the Republicans got that one right? Nope. Just 39 percent thought the GOP maintained the right balance between criticizing the Democrats and saying positive things about themselves, compared to 50 percent who thought they spent too much time criticizing the Democrats. By contrast, in 2000, 45 percent thought the GOP maintained the right balance in their convention, compared to 38 percent who thought they spent too much time criticizing.

Can anyone seriously maintain, then, that this year's GOP convention was such a blockbuster that it could produce a surge in Republican party ID that dwarfs that produced by 9/11? It just does not compute.

Still not convinced that party-weighting should at least be considered to correct for sudden partisan imbalances in polls? I close with the words of Charlie Cook in his latest online column:

...Pollsters acknowledge variances from one poll to the next in gender, race, income and education, and they correct for it, but refuse to acknowledge that partisan numbers fluctuate just the same, and need to be corrected.

My own view is that samples should be weighted by party to the average party breakdown in a combination of the polls for the last several months, linking it to a very large sample of combined surveys to reduce sampling error. While this method might be a bit sluggish if party identification is changing dramatically, it would mean that when a candidate is gaining or dropping, it is most likely because they really are, not because of a sample that is too tilted in favor of one party or the other. If Republicans are indeed gaining in party identification, it will show up after a couple of polls in the average.

You tell 'em, Charlie.