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Do Skewed Polls Tilt To Obama?

Are polls overstating President Obama's lead over Mitt Romney

That's become a serious question for some analysts as several opinion polls show large leads for Obama, but the number of Democrats surveyed far exceed the number of Republicans.

A Quinnipiac/New York Times/CBS News survey on Wednesday found Obama leading Romney in Florida 53%-44% and in Ohio 53%-43%.

Yet Democrat respondents exceed Republicans by 9 percentage points in the poll, 36%-27% in Florida and 35%-26% in Ohio.

This Is Not 2008 That roughly matches up with the 2008 turnout in Ohio, where exit polls showed 39% of voters were Democrats vs. 31% Republicans, but not with Florida where Democrats exceeded Republicans by only 37%-34%.

Furthermore, this is not 2008. It's unlikely that Democrat voters will exceed Republicans to the extent they did four years ago, especially since many polls show that the GOP is more motivated to vote than Democrats. Indeed, the Quinnipiac polls find that among voters who are most enthusiastic, Republicans top Democrats 52%-48% in Florida and 53%-43% in Ohio.

By contrast, polls with closer partisan breakdowns tend to show closer results.

Rasmussen Reports' daily tracking poll shows a 46% tie, while its tracking poll of key swing states gives Obama a slim 46%-45% edge. Rasmussen's partisan breakdown is about 38% Democrat and 36% GOP.

'Two Schools' On Party ID "There are two schools of thought on partisan breakdown," said Raghavan Mayur, president of TechnoMetrica Market Intelligence, which conducts the IBD/TIPP poll. "One school says that party identification is a fleeting feeling rather than a hard demographic like gender or age. The second school weights the data for party identification based on what they estimate the partisan breakdown is.

Mayur uses a hybrid approach. If he gets a result that deviates significantly from previous polls, he will weight the party identification based on the average of his three previous polls.

Rasmussen weights the data based on what projected turnout looks like over a six-week time period based on a sample of likely voters. The resulting targets are applied to its daily samples.

Quinnipiac belongs to the first school of thought. While it does weight for demographic characteristics like age and race, it considers party identification to be a shifting characteristic.

"There is no standard for party ID," said Peter Brown, assistant director at Quinnipac. "Our recent poll reflects the fact that President Obama has had a good month and last week Romney's comments dominated the news media.

That impacts the party breakdown in the Quinnipiac poll, and respondents may be less willing to identify as Republicans and more willing to identify as independents.

That may be reflected in the fact that in the survey Romney is winning independents in Florida 49%-46% and in Ohio 47%-46%.

On the other hand, polls showing Romney slightly ahead among independents but trailing badly overall in key swing states may indicate Democrat oversampling.