TNS Opinion was commissioned to conduct the survey using Computer Assisted Telephone Interviews in all countries except Poland, Slovakia, Romania, and Turkey, where lower telephone penetration necessitated the use of face-to-face interviews.
In all countries, a random sample of approximately 1,000 men and women, 18 years of age and older, was interviewed. Interviews were conducted primarily between June 3 and June 27, 2013; they were suspended for a week in Turkey, then resumed and completed by July 2.
For results based on the national samples in each of the 13 countries surveyed, one can say with 95% confidence that the maximum margin of error attributable to sampling and other random effects is plus or minus three percentage points. For results based on the total European sample, the margin of error is plus or minus one percentage point. In addition to sampling error, question wording and practical difficulties in conducting surveys can also introduce error or bias into the findings of public opinion polls.
For trended questions first asked before 2010, averages were weighted on the basis of the size of the adult population in each country to maintain consistency with previous years’ reports. For questions that started in 2010 or later, the results were also weighted so that the sample matches certain population characteristics, including age, gender, education, and region.
When processing is complete, data from the survey are deposited with the Inter-University Consortium for Political and Social Research at the University of Michigan (ICPSR), the Roper Center for Public Opinion Research at the University of Connecticut, and the GESIS-Leibniz Institute for the Social Sciences and are available to scholars and other interested parties.
Note on European averages
Over time, additional European countries have been added to the survey. While the addition of new countries has affected the Europe-wide average, the impact has usually not been statistically significant. Therefore, for ease of presentation, we have treated several different averages as if they were part of one average. When the EU average is reported for previous years, this is based on the EU-7 average from 2002-2003, the EU-9 average from 2004-2006, the EU-10 average from 2007-2010 and the EU-11 average from 2011.
Table of European Averages Reported:
|EU7||2002-2003||U.K., France, Germany, the Netherlands, Italy, Poland, and (2003) Portugal|
|EU9||2004-2006||EU7 countries plus Slovakia and Spain|
|EU10||2007-2010||EU9 countries plus Romania|
|EU11||2011||EU10 countries plus Sweden|
|2002||U.S. + E6||France, Germany, Italy, the Netherlands, Poland, U.K.|
|2003||U.S. + E7||France, Germany, Italy, the Netherlands, Poland, U.K., Portugal|
|U.S. + E10||France, Germany, Italy, the Netherlands, Poland, U.K., Portugal, Turkey, Slovakia, Spain|
|U.S. + E12||France, Germany, Italy, the Netherlands, Poland, U.K., Portugal, Turkey, Slovakia, Spain, Bulgaria, Romania|
|2011||U.S. + E13||France, Germany, Italy, the Netherlands, Poland, U.K., Portugal, Turkey, Slovakia, Spain, Bulgaria, Romania, Sweden|
|France, Germany, Italy, the Netherlands, Poland, U.K., Portugal, Turkey, Slovakia, Spain, Bulgaria, Romania, Sweden, Russia|
|2013||U.S.+E12||France, Germany, Italy, the Netherlands, Poland, U.K., Portugal, Turkey, Slovakia, Spain, Romania, Sweden|