Pew Research Center regularly conducts public opinion surveys in countries outside the United States as part of its ongoing exploration of attitudes, values and behaviors around the globe. To date, the Center has conducted more than 800,000 interviews in over 110 countries, mainly in conjunction with the longstanding Global Attitudes and Religion & Public Life projects but including others such as a 20-country international science study and another on digital connectivity in 11 emerging economies.

Cross-national studies constitute the bulk of Pew Research Center’s international survey research. Such studies pose special challenges when it comes to ensuring the comparability of data across multiple languages, cultures and contexts. To learn more about the challenges and best practices of polling in foreign countries and in multiple languages, see here.

Pew Research Center staff are responsible for the overall design and execution of each cross-national survey project, including topical focus, questionnaire development, countries to be surveyed and sample design. The Center’s staff frequently contract with a coordinating vendor to identify local, reputable research organizations, which are hired to collaborate on all aspects of sample and questionnaire design, survey administration and data processing. Both coordinating vendors and local research organizations are consulted on matters of sampling, fieldwork logistics, data quality and weighting. In addition, Pew Research Center often seeks the advice of subject matter experts and experienced survey researchers regarding the design and content of its cross-national studies.

Field periods for cross-national studies vary by country, study complexity and mode of administration, typically ranging from four to eight weeks. To the degree possible, Pew Research Center attempts to synchronize fieldwork across countries in order to minimize the chance that major events or developments might interfere with the comparability of results.

Pew Research Center’s cross-national studies are designed to be nationally representative using probability-based methods and target the non-institutional adult population (18 and older) in each country. The Center strives for samples that cover as much of the adult population as possible, given logistical, security and other constraints. Coverage limitations are noted in the detailed methods for each country.

Sample sizes for Pew Research Center’s cross-national studies are usually designed to yield at least 1,000 interviews, though larger samples may be required for more robust within-country comparisons. Reported margins of error account for design effects due to clustering, stratification and weighting.

In the case of both telephone and face-to-face surveys, weighting procedures correct for unequal selection probabilities as well as adjust to key sociodemographic distributions – such as gender, age and education – to align as closely as possible with reliable, official population statistics. To learn about the weighting approach used for U.S. surveys using the nationally representative online American Trends Panel, visit here.

Pew Research Center is a charter member of the American Association of Public Opinion Research (AAPOR) Transparency Initiative.