Survey Methods

What does the migration to online polling mean for the country's trove of public opinion data gathered over the past four decades?

How does the way a poll is conducted influence the answers people give?

Pew Research Center conducts surveys over the phone and, increasingly, online. But these two formats don’t always produce identical results.

Evolution remains a contentious issue. When asked about it, highly religious Americans' responses can vary depending on how the question is asked.

Measuring public opinion on evolution has never been an easy task for survey researchers.

The way polling questions are asked can influence people's answers. Survey experiments are one way to measure the degree to which different questions elicit different answers.

Detailed information on Pew Research Center international survey meethodology, such as mode of interview, sampling design, margin of error, and design effect, for each country we survey, organized by survey, country and year.

Pew Research Center uses benchmarking questions to ensure our surveys are accurate. Learn why and how we use these questions.

On election night 2018, besides the exit polls there will be an additional source of data on who voted and why, developed by The Associated Press, Fox News and NORC at the University of Chicago and based on a very different methodology. That means that depending on where you go for election news, you may get a somewhat different portrait of this year's electorate.

Given the wide range of people we speak to for our polls – and the issues we ask them about – it’s important to be as clear as possible about exactly who says what. In research circles, this practice is sometimes called “defining the universe."