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Measuring public opinion: lesson overview

What is public opinion, and why do political scientists measure it?

Public opinion, in short, is a fancy way of saying “what people think.” This might be what people think the government should focus on, how likely they are to vote for a candidate, or whether they pay much attention to politics at all. Political candidates and government officials often determine which policies to pursue in response to public opinion.
Pollsters measure public opinion in a variety of ways, including scientific polling. The results of public opinion polls influence public policies, elections, and the decisions made by government institutions. But not all public opinion data is equally reliable: the type of poll used, the methods and sampling techniques, and the type and format of the questions all affect the accuracy of poll results.

Key terms

public opinionHow people feel about issues, candidates, and public officials. Polls are a common way to measure public opinion.
populationA group of people that a researcher wants to study. This might be a large group, such as all voting-age citizens in the United States, or a smaller group like members of a club or church.
sampleThe group of people a researcher surveys to gauge the whole population’s opinion. Researchers study samples because it’s impossible to interview everyone in a population.
sampling techniqueThe process by which pollsters select respondents to a survey or the sample population for a poll.
sampling errorThe predicted difference between the average opinion expressed by survey respondents and the average opinion in the population; also called the margin of error. As the sample size increases, the margin of error decreases.
random sampleA random selection from a population, random sampling techniques ensures an equal probability of individuals being selected for a survey or poll.
representative sampleA relatively small number of respondents who accurately reflect the variety of opinions, demographics, etc. in the broader population. In political science, a representative sample is usually between 400 and 2,000 respondents.

Types of polls

benchmark pollsPolls conducted by a campaign as a race for office begins. These polls provide the campaign with a basis for comparison for later polls, so that the candidate can see if their likelihood of winning the office is increasing or decreasing.
opinion pollsA poll taken by sampling a small section of the public in an effort to predict election results or to estimate public attitudes on issues.
tracking pollsA survey performed repeatedly with the same group of people to check and measure changes of opinion.
entrance pollsPerformed on Election Day, these surveys are taken as voters enter their voting location.
exit pollsPerformed on Election Day, these surveys are taken as voters exit their voting location. Media outlets often rely on exit polls to determine election results, even before the ballots have been counted.
mass surveyThe most common type of survey; a way to measure public opinion by interviewing a large sample of the population.
focus groupA small, demographically-diverse group of people assembled for an in-depth group discussion. Researchers study the group’s reactions to an idea or candidate in order to gauge how the broader public might react.

Review questions

  1. Rita Skeeter selected 10 students from two of the four houses at Hogwarts School of Witchcraft and Wizardry, Gryffindor and Ravenclaw, to gauge opinions about the best teacher at the school. Six of the students she surveyed responded that Professor McGonagall was the best teacher, three responded that Professor Flitwick was the best teacher, and one responded that Professor Snape was the best teacher. Rita published the results of her survey in the Daily Prophet with the headline “McGonagall Voted Best Teacher at Hogwarts.”
Was Rita’s survey reliable? Why or why not?
  1. Arjun, Caitlyn, and Olivia are all running for class president. On election day, students from the journalism club stationed themselves outside of the voting booth and conducted an exit poll. At the end of the school day, they tallied 321 votes for Caitlyn, 297 votes for Olivia, and 266 votes for Arjun. The next day, after counting the votes, the principal announced that Olivia had won the election with 375 votes.
What likely accounts for the difference between the exit poll and the actual results?

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