By

Stephanie Condon /

CBS News/ October 19, 2012, 3:30 PM

Confused by all the polls? Pollsters explain the variation

As recently as two weeks ago, political prognosticators were looking at polls and declaring, "If Romney would have to pull off a miracle to close the gap in national polling, he has no shot at matching the president in the electoral college."

This week, with Gallup polling showing Mitt Romney with a strong national lead over President Obama, some conservatives are pointing to the Republican candidate's likely victory.

The latest polls out of Wisconsin and Iowa, meanwhile, show Mr. Obama with a modest but clear lead in the two battleground states.

For what it's worth, a CBS News/YouGov simulation this week showed that, had the election been held at that point in time, Mr. Obama would have held a slight Electoral College edge. This simulation, however -- as with every survey -- represents no more than a snapshot in time.

"Poll results reflect the mindset of voters during the time the poll was conducted," CBS News director of surveys Sarah Dutton explained. "Those voters can change their minds later, or decide not to vote, or not be able to get to the polls on Election Day to vote."

Even among polls conducted over the same span of time, different methodologies -- whether it's differences in the way survey samples are chosen or differences in the way the surveys are conducted -- can lead to different results.

"It's certainly important to understand whether a poll includes calls to cell phones, whether it's done online, whether live interviewers ask the questions, when the poll was conducted - those are all part of a poll's methodology," Dutton said. "Consumers of polls should be aware that not all polls are conducted the same way, and some utilize a more rigorous methodology than others."

Furthermore, some polls track registered voters while others track likely voters -- and pollsters may differ in how they determine who is a "likely voter." Some polls look at people who say they will definitely vote, Dutton said, while others identify likely voters based on their responses to a number of questions, such as past vote history, whether they know where their voting place is, and whether they will definitely vote in this election.

Gallup's tracking poll provides a daily, seven-day rolling average of both likely voters and registered voters. This week's figures show a noticeable difference between the two groups: Today, Romney led Mr. Obama by six points among likely voters, 51 to 45 percent. His lead among registered voters, however, was just one point, 48 percent to 47 percent. Gallup editor-in-chief Frank Newport told the Washington Post that Gallup's likely voter model "takes into account changes in the response to questions about how closely they're following and how enthusiastic they are." The relatively large difference between the likely voter numbers and registered voter numbers may be because the likely voter model is, as Newport said, "very sensitive to changes in enthusiasm."

Polling experts discourage using any single poll to predict the outcome of an election. That said, looking at poll averages, and multiple polls over time, can provide insights into broader overall trends in the election. Quinnipiac University Polling Institute assistant director Peter Brown emphasized that it's only worth comparing trends from the same polling outfit -- there would be no use, for instance, in comparing a Gallup poll with a CBS News poll because of the different methodologies.

This month, there have been some clear trends.

"Clearly, two weeks and three days ago before the first debate, there were an awful lot of people who, according to the polls, thought Mr. Romney's chance of victory were small," Brown said. "Obviously, the polls have changed. Overall, Mr. Romney's certainly doing better than before the first debate."

© 2012 CBS Interactive Inc. All Rights Reserved.
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    Stephanie Condon is a political reporter for CBSNews.com.

182 Comments Add a Comment
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stupa5 says:
See what the top GOP thinks about the flip flopper Romney

http://www.youtube.com/watch?v=hRJa2OaiwWw
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fredimeier says:
Human beings are by nature more motivated to start something new, other than to support something existing.
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NicholasKrizman replies:
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There is nothing new about Mittens - just a Mormon version of GW Bush - remember the asshat that drove the country into the ground.
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hnferiw says:
Romney will lose the election...
because everybody will remember his lies about the auto industry when they vote!
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fredimeier says:
Human beings are by nature more motivated to start something new, other than to support something existing.
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Johnthinker says:
As we watch Hurricane Sandy tear up America, I hear Romney's words echoing in my head 'I will burn all the dirty coal I can find: open every oil well, I will stop research into clean energy'.

And I wonder what the storms of the future will be like. You now will decide what storms your children will face.
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seabass6251 replies:
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As we watch Hurricane Sandy tear up America, I hear Romney's words echoing in my head 'I will burn all the dirty coal I can find: open every oil well, I will stop research into clean energy'.

You must have taken that straight from transcript. Can you post the link???
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mturner1938 says:
Did anyone read where Rahm Emmanuel says that Obama is ahead in the early voting? Anyone, like me, wonder where he is getting his information before the votes are tallied up?
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agelmers replies:
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You are talking about the evil one. You know where the evil one gets his information.
Clofitas1 replies:
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In some states voters much register by party, so it is assumed that most people who are registered as Democrats are voting for Obama and most people registered as Republicans are voting for Romney. I think that is where he is getting his info. Based on what I read Democrats are winning the early vote count by a margin of about 2:1.
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Passthebeer says:
If you think these polls are on the up and up read how Chris Christie knew in advance of the first debate that the polls would change dramatically after the first debate. How could anyone have so accurately predicted this? http://codeforeblog.com/?p=1207
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Clofitas1 replies:
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Because he knew Romney was going to make a shift to the center. By changing his conservative views he attracts more independent voters and he seems more likeable to people who thought he was disgusting before. I think that is how Christie was able to make that prediction.

It is unfortunate that Obama gave him the opening by allowing him to win that first debate. I think Obama was trying to not seem the "angry Black man". After the last debate, I read comments on several websites that Obama seemed angry...lol. What a huge double standard. Romney can lie and interrupt and get caught in a lie and Obama was the one being criticized.
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Passthebeer says:
BS. Read this. Understand these pollsters. How is it that Chris Christie knew in advanceof the first debate that the polls would dramatically change infavor of Romney. How did he know that? Read how. http://codeforeblog.com/?p=1207
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ronhum says:
Does no one follow any of the meta analysis polls?
Obama 291 Romney 247 Likelyhood of Obama re election - 87-96 percent. Polls are stable and the cake seems to be baked. Bar some black swan, Obama will get a second term.
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eroteme2 says:
Good Sarah Dutton enlightens us, informing that 'Poll results reflect the mindset of voters during the time the poll was conducted'. What fantastic insight! Thank you, Sarah. It is no wonder you have been selected to serve as CBS News Director of Surveys.
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