Pollster.com: Zogby Internet Poll Trial Heats are Odd

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The cable networks — and certain “rival campaigns” — are all over the news that Hillary Clinton is suddenly losing in national trial heats against all five Republican hopefuls… including mike Huckabee. Charles Franklin at Pollster.com takes a close look at why these polling results are, as he says, “odd.” (I think he’s understating the case.)

The problems in this poll go beyond the selection issues that plague “interactive” polls of all types, and show themselves in the results themselves:

If Clinton really has suddenly become 10 points less attractive, we’d expect all four Republicans paired against her to do BETTER than their trend estimates when facing her. But what happens is Clinton goes down and they don’t do any better. That is hard to reconcile with a real change in Clinton’s support….

The Zogby Internet polling has a questionable track record in statewide races for Senate and Governor in 2006, where they often far over-estimated the competitiveness of races compared to conventional phone polls taken at the same time. One way to make sense of those problems turns out not to help much here. It is reasonable that the people who volunteer to take political polls over the internet are considerably more interested in politics (and likely more strongly partisan) than is a random sample of likely voters. That should be expected to lead to fewer people with “don’t know” responses as better informed and more partisan respondents are likely to both know more about the candidates and to have made up their minds sooner than a proper random sample. That helps explain why Zogby’s 2006 internet polls looked as they did.

But this does no good in Clinton’s case. What we see is that MORE internet respondents are undecided about their vote between Clinton and four Republicans than the trend estimates based on less involved and partisan phone samples show….How could it be that a sample that is almost certainly more involved, knowledgeable and partisan can be LESS decided about Cinton, the single best known figure in the race? Again, a tortured story might be constructed, but I think a simpler explanation is that this result is not consistent within the Zogby data itself, or in comparison with outside polling.

Where does this leave us? Puzzled. If these results came from voting machines, I’d suspect that something in the ballot design or the recording mechanism caused a modest but consistent undercount of the Clinton support. The effect seems confined only to that one candidate, and not to any others, Democrats or Republicans. And there was no boost in support for the Republicans paired against Clinton. In this case, I’m similarly inclined to wonder if there is the possibility that the Zogby online survey had a glitch that caused a systematic “undervote” for Clinton. Certainly if my research assistant brought me these results, I’d want to check the software for mistakes before I published it.

Now, I suspect, Clinton’s support is soft, and that as the race heats up, things will tighten. But this poll isn’t proof of that. (For a discussion of how you might tell if her support is soft, please suffer through this lower-fi than usual podcast here.)

UPDATE: A markedly less “odd” poll from Gallup that puts Clinton — and Obama — ahead in trial heats.