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California Super Tuesday Pollster Comparison

Topics: 2008

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There is quite a bit of disagreement in the California polls, so let's do a Pollster Comparison to see who says what.

The Democratic race has the biggest gap across pollsters. Most see Clinton ahead, but disagree on how much the race has tightened. But Suffolk and Rasmussen put Obama just barely ahead in their final polls. And the big difference is in the Zogby/Reuters/C-SPAN poll that sees Obama not only ahead but expanding his lead to double digits.

That gives us a range of results from Obama ahead by more than 10 to Clinton ahead by 10. Somebody is not quite right here. But who? And why?

Across all the polls, Clinton is relatively flat while Obama has gained. But looking at each poll and each candidate reveals more differences across pollsters.

Both Zogby and the Field poll find some decline for Clinton while others have her flat or rising (SurveyUSA and Rasmussen).

2PollstersCAClinton.png

Everyone sees Obama either flat or rising, with no pollster (who has at least 2 polls) seeng Obama declining. But the extent of the rise, and how high Obama's starting point was, differs quite a bit across pollsters. Survey USA and Rasmussen both see Obama gains, but SurveyUSA offsets that by measuring gains for Clinton as well, resulting in relatively little net change over their last three polls. Rasmussen, on the other hand, has Clinton gains but even bigger Obama gains, resulting in a net decline and a final poll with Obama just barely ahead.

3PollstersCAObama.png

The Zogby polls in contrast find both Clinton declines AND Obama gains, making for a net change that strongly favors Obama and results in his 13 point lead in the final Zogby poll for California.

On the Republican side, we also see substantial differences. Two pollsters see a dramatic tightening of the race. Rasmussen and SurveyUSA estimate that McCain's earlier lead has now collapsed to a dead heat. (A single ARG poll also sees a dead heat, but has no over time data for comparison of trend.) In contrast the LA Times/CNN/Politico and Field polls both find McCain gaining some ground in their polls. These two are a bit stale now, but showed gains even when Rasmussen and SurveyUSA saw declines, so this is not only a difference of survey dates.

Zogby/Reuters/CSPAN is again quite different, finding Romney leading in all three polls and expanding his lead to high single-digits in the last two polls.

4PollstersCAMcCainRomney.png

Across the Republican polls, the differences are almost all matters of the degree of increase for both McCain and Romney. All polls agree that McCain has been increasing his support. But they also agree that Romney is rising sharply. The differences in net support have a lot to do with differing estimates of how fast and how far Romney has risen. Those with the greatest Romney rises have him catching McCain or leading him.

Given the length of time it is likely to take to count the California vote, it may be Thursday before we know which of these polls was closer to the end result.

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6PollstersCARomney.png

Cross-posted at Political Arithmetik.

 

Comments
Chris G:

just eyeballing these it looks like the polls show, at any given time point (roughly), about 1/2 the variability in support for Obama and Romney as they do for Clinton and McCain respectively. is that right? if so I think this implies differences in undecided-vs-front runner that're the most operative here

also, important to keep in mind that release-by-pollster is just as time-dependent as changes in candidate preference. zogby looks to have bias against front runners in both races, and also released 3 polls all since 2/1, giving exaggerated acceleration in support towards underdogs (if you simply average or do your local regression)

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Elliot:

I sense that many independents (who can choose to vote either Repub or Dem once they are at the polls) here in Ca who may have indicated that they would vote for Hillary will, in fact, decide to vote for McCain today. For many moderates, it may be a decision between these two, rather than between Barack & Hillary or Romney & McCain. I think this will affect the democratic race much more then the republican race, mainly because of Hillary's white house baggage & a sense of her husband's leadership failures. As a result, we may see Obama do better than what the polls have been indicating.

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Shane:

"I sense that many independents (who can choose to vote either Repub or Dem once they are at the polls) here in Ca who may have indicated that they would vote for Hillary will, in fact, decide to vote for McCain today."

Two notes:
1.How do you "sense" these things?
2.As far as I know, the Republican primary is a closed primary. I think Independents can only vote Dem....

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Joey Jo Jo:

Incorrect--Independents can only vote in the Dem primary in CA today

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Elliot,

Independents or "decline to state" as they are called in CA cannot vote in the Republican primary.

Sarah

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Joey Jo Jo:

This open Dem and closed Rep primary, by the way, benefits Obama. He has been performing much better among registered independents (DTS voters) in every open primary so far and in CA polling by virtually every pollster.

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Elliot :

My mistake about the open Repub primary! Thanks. I'll need to rethink this, evidently. My immediate thought is that Joey Jo Jo has a good point, probably supported by the fact that DTS voters are generally younger than those who are party affiliated. All of the exit polls I have seen from other states show younger voters leaning towards Obama in primaries.

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richard Pollara:

If Zogby's latest poll proves inaccurate, they will have done a disservice to polling and to voters. MSNBC, in a piece with Tom Brokaw, highlighted Zogby. Brokaw said, "If these numbers hold up, it is very bad news for the Clinton Campaign." It sounded to me like he was "tolling the bell". It is dangerous territory when a poll, which is dramatically at odds with most other polls, becomes both a news event and has the potential to influence voter behavior on election day. Maybe we are at the point where polling ought to stop a number of days before an election? It might make voters think more about the issues and not so much about getting on the winning bandwagon.

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john:

Hillary will win. John Zogby's brother works for Obama so come on...., if it were not for Zogby, Obama would be "Surging"

You guys never learn from NH. I believe Survey USA b/c they are not biased and has been right 18 out of 24 times.

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richard - that would assume that anyone watched Brokaw on MSNBC.

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demkid:

How about percentage of Latino voters? I read earlier that this is a significant difference between Zogby and SurveyUSA. Are there indications that the total Latino percentage will be somewhat different than it was in 2004?

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tilthouse:

I'd be more interested to see the variations can be explained by differences in things like turnout models, demographic models, etc.

Do the Obama-leading polls show a higher turnout? Or a higher youth turnout? Or somesuch thing?

Or is it just noise?

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sam:

No doubt that something is happening out there. Obama is definately picking up steam, not only in California but in polls accross the US.

The question is, what does it mean? I think Hillary will win CA, but by a very tight margin. Given the media's propensity to see Obama "surge", I think a draw favors him going forward.

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richard Pollara:

AVI: By having the most respected figure at NBC, Tom Brokaw, do the story, they make it instantly credible. Had MSNBC said, "there is a 23 point difference between two polls conducted yesterday." that would have been a fair report (and a better news story as well!). But the story line they want to promote is about a 4th quarter comeback. It makes better theater but poor reporting.

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Gavin:

I think Obama's leads have been substantial and show real progress, however Zogby is off the mark and too aggressive in his gains. I guess we will have to wait and see until they can break down the voting that occurred today compared to early voting.

But no doubt that Clinton will win by a good enough margin to have a field day with the press. She will carry the headlines.

Obama came in very tight in key demographics but not enough to push back against her early voting gains; they really tipped her over the mark, in my humble opinion.

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Frank:

"But no doubt that Clinton will win by a good enough margin to have a field day with the press. She will carry the headlines."

I really wonder if this is true. I am very much enamored by both candidates, but I have been dumfounded by how 'in love' the press is with Obama - they have made it very clear - as long as he is not routed tonight he will come out a "winner" and unless Hillary has a decisive double-digit victory she really loses.

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