Pew Research Center conducted surveys among 24,599 adults (ages 18 and older) across 15 countries in Western Europe between April 2017 and August 2017. Interviewing was carried out under the direction of GfK Belgium using both cellphones and landlines. The questionnaire was designed by Pew Research Center staff in consultation with subject matter experts and advisers to the project. The wording of several questions was subjected to cognitive testing, and the full survey questionnaire was pretested in all countries prior to fieldwork. Survey questions address attitudes toward religion, respondent income, key social issues, general opinions about religion's role in society.
