Methodological Research

Pew Research Center’s American Trends Panel (ATP) is now the Center’s principal source of data for U.S. public opinion research.

Response rates to telephone public opinion polls conducted by Pew Research Center have resumed their decline, to 7% in 2017 and 6% in 2018.

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.

Pew Research Center now uses 1996 as the last birth year for Millennials in our work. President Michael Dimock explains why.

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.