Polling: a look inside the machinery of public opinion surveys

Sampling has been complicated by the rise of cellphones. In Gallup's June survey, 40 percent of respondents were reached on a cellphone. Young people are more likely to have only a cellphone, while older Americans tend to still have land lines.

Michael Traugott, a professor of political science and communication studies at the University of Michigan, says that though it can cost twice as much to reach people on cellphones – usually calls have to be made several times – it's imperative to include that population.

"If there is a greater proportion or probability of young people and minorities adopting cellphones early, earlier than the rest of the population, and you have a candidate who is strongly favored among both, like Barack Obama, you could underestimate his support if you exclude cellphone-only or cellphone-primarily people from your sample," Mr. Traugott says.

Experts caution consumers to be wary of the results if a poll doesn't contact respondents via both means. This isn't always easy to determine, however. Disclosure of poll methodology is not uniform, though some organizations offer online links to information.

Krosnick believes that media outlets should require pollsters to disclose their methodologies in a standard format to get news coverage.

The call-cubicle-to-voter connection

Gallup's Omaha call center is similar to many cubicle-lined work spaces. Workers post personal keepsakes at their desks – pet pictures, a teddy bear, even a book of Psalms. They stash snacks for breaks – sodas, Red Bull, a box of Nips hard candies.

Unlike many offices, though, there's a steady buzz of chatter. Everyone in the room – approximately 140 callers – is talking at once. Most are not working on the political poll. Even one of America's premier pollsters needs to make money – and that largely comes from conducting satisfaction or employee surveys for corporate clients. (Gallup wouldn't discuss the cost of its June political poll, but Pew's Mr. Keeter estimates it can cost between $30 and $50 per respondent – or about $30,000 to $50,000 for a survey of 1,000 people. As for pay, Gallup interviewers are given an hourly quota of calls and receive bonuses if they go over that, says a veteran Gallup caller.)

Jablonski has been with Gallup since 1991. He interviewed for the June political poll with alacrity. He snagged a willing respondent on the phone and dived right in. (For legal reasons, the Monitor was not permitted to listen to the respondents' side of the calls.) This female interviewee, age 19, Jablonski said later, is supporting Obama because she likes his views on gay marriage and that he led the effort to kill Osama bin Laden. She says she doesn't trust anyone else running for president.

Dressed casually in shorts and flip-flops, Jablonski encourages her participation.

"I want you to know you did a really good job, and I really appreciate your time," he says.

Jablonski said after the call that he gets excited when he sees Gallup's surveys mentioned online or on cable TV. "We don't represent Barack Obama. We don't represent Mitt Romney. We represent the American people," he said.

"There's a real sense of pride in that [work]," he added. "To know that's data I collected."

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