Other questions are leading. Such as this example Krosnick suggests: "Some people believe that Barack Obama was born outside the United States. How much do you agree or disagree?"
The question sends a signal that the interviewer – or survey sponsor – might have an agenda. A more neutral way to ask would be to also include a mention that others believe Obama was born in the US.
Yet another way to skew results, says Krosnick, is to target respondents who favor a candidate or issue. "If you prefer to slant a poll in a particular direction, then you can make decisions about who to go after and how to go after them," he says. "If a candidate does better in higher socioeconomic status [areas], use more respondents in [those areas]."
Once Newport and his colleagues formulate poll questions, the survey is sent to Tara McGhee, a survey design editor in Omaha. Ms. McGhee takes every path through the survey to make sure it's programmed correctly; in other words, depending on a respondent's reply – if he or she offers support for Romney or Obama, for example – that person is branched through the survey questions differently. Follow-up questions are prompted by their answers. She also checks spelling and grammar.
"We are expected to be perfect," says McGhee, who has been with Gallup for 10 years. "We are the last set of eyes on it. My personal mission is quality."