Predicting the President

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People at a political conference complete a straw poll in Maryland. A straw poll is an unofficial poll taken to gauge people’s opinions on certain issue.

On Tuesday, November 8, voters will cast their ballots for the next president of the United States. But even before the votes are counted, people want to know: Which candidate has the best shot at winning?

To answer that question, we turn to pollsters. These political pros interview voters and use their responses to make predictions about who will win an election. Polls can also be used to find out what voters think and care about. Pollsters use data—and math—to make smart guesses about these topics.

Tuesday, November 8 is election day. Voters will cast their ballots for the next president of the United States. But even before the votes are counted, people want to know something. Which candidate has the best shot at winning?

To answer that question, we turn to pollsters . These political pros interview voters. Then they use their responses to make predictions about who will win an election. Polls can also be used to find out what voters think. And what they care about. Pollsters use data and math. This information helps them make smart guesses about these topics.

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A voter leaves a polling place during the Maryland primary on April 26.

Pollsters can’t speak to every possible voter. Instead they talk to a small group called a sample.

“The trick is that the sample has to represent the much bigger number of people who vote,” says J. Ann Selzer. She’s the president of Selzer & Co., her polling company in WestDes Moines, Iowa.

Pollsters might ask people in the sample which candidate they support, what issues they care about, and how likely they are to vote. Then pollsters sit down to do some math.

“The most important quality in a pollster is a math-centered mind,” says Selzer. “We do division daily. We take the number of people who gave a certain answer and divide it by the total number we talked to.” Pollsters use the result to calculate a percentage.

These percentages allow pollsters to make comparisons between groups, such as men and women or older and younger voters. This helps pollsters predict how certain groups of people will vote on election day.

Pollsters can't speak to every possible voter. Instead they talk to a small group. It's called a sample .

"The trick is that the sample has to represent the much bigger number of people who vote," says J. Ann Selzer. She's the president of Selzer & Co. That's her polling company in West Des Moines, Iowa.

Pollsters might ask people in the sample which candidate they support. Or what issues they care about. Or even how likely they are to vote. Then pollsters sit down to do some math.

"The most important quality in a pollster is a math-centered mind," says Selzer. "We do division daily. We take the number of people who gave a certain answer. Then we divide it by the total number we talked to." Pollsters use the result to calculate a percentage.

These percentages allow pollsters to make comparisons between groups. These groups include men and women. Or older and younger voters. These comparisons help pollsters predict how certain groups of people will vote on election day.

Rue des Archives/The Granger Collection

President Harry S. Truman displays the front page of a newspaper after polls incorrectly predicted victory for his opponent in 1948.

Polls aren’t always 100 percent correct. Sometimes they’re totally wrong! The most famous example of this happened in 1948. Pollsters predicted that Thomas E. Dewey would win the presidency over Harry S. Truman. The polls favored Dewey so strongly that the Chicago Daily Tribune printed a headline declaring Dewey’s victory. Imagine everyone’s surprise when Truman won!

Polls can be misleading for many reasons. Questions with confusing wording can skew results. If the sample of respondents isn’t diverse enough, the poll won’t correctly reflect the opinions of all voters. Professional pollsters take great care to minimize these errors.

Polls aren't always 100 percent correct. Sometimes they're totally wrong! The most famous example of this happened in 1948. Pollsters predicted that Thomas E. Dewey would win the presidency over Harry S. Truman. The polls favored Dewey very strongly. The Chicago Daily Tribune even printed a headline declaring Dewey's victory. Imagine everyone's surprise when Truman won!

Polls can be misleading for many reasons. Questions with confusing wording can skew results. Sometimes the sample of respondents isn't diverse enough. In that case, the poll won't correctly reflect the opinions of all voters. Professional pollsters take great care to minimize these errors.

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To be eligible to vote, a person must be an American citizen at least 18 years of age.

Reliable polls serve an important function in democracy. They help politicians understand what voters are thinking. They also let the public know which candidates are in the lead.

Most important, “polls are a way for the voice of the people to be heard,” says Julia Clark. She’s a senior vice president at the polling company Ipsos in Chicago, Illinois. “I think that’s good for politics and good for everyone.”

Reliable polls serve an important function in democracy. They help politicians understand what voters are thinking. They also let the public know which candidates are in the lead.

Most important, "polls are a way for the voice of the people to be heard," says Julia Clark. She's a senior vice president at the polling company Ipsos in Chicago, Illinois. "I think that's good for politics and good for everyone."

Let’s say students at one elementary school took a poll to find out their favorite president of all time. The results are below.

Display this data in a pictograph.

What would you title your pictograph?

What amount does each picto represent?

Say you wanted to display the results of the tally from No. 1 as a bar graph. What increment would you choose for the scale of the bar graph?

A pollster asks 1,000 people what issues they consider the most important. Fill in the blanks below to show how you would graph the results of this poll.