The EVS methodology has been greatly strengthened for the current wave to bring the data quality to a high level. Each national survey conforms to guidelines designed to ensure quality and consistency.

Here below a summary of the main aspects of EVS2017 methodology. Read more about what has been done in EVS2017 to reach data quality.

• Respondents are interviewed face-to-face for approximately one hour. However, in the 5^th wave of EVS, there is the possibility to carry out a mixed-mode data collection.
• The Countries translated the Master Questionnaire following a team approach. The process was managed, implemented, and documented on a web-based platform, the Translation Management Tool (TMT).
• In each country, the Master Questionnaire was translated in each language spoken by at least 5% of the population.
• Countries sharing a language (e.g., French, German, Russian) cooperated for the harmonization between the same-language translations of the EVS2017 questionnaire. Some countries cooperated in the whole translation process, in other cases one country’s translation was used as a basis for the other countries’ questionnaires.
• The national effective sample size is 1200 [countries with a population over 2 million] and 1000 [countries with a population below 2 million]
• Random samples give full coverage of the target population (persons 18 years and older resident in private households, regardless of nationality or language).
• Information is provided for weighting purposes, including the complete hierarchical structure of the sampling design, the size of the stages/clusters at each step, population distributions, and so on.
• Repeated revisits are made to interview the person randomly selected.
• The questionnaire contains pre-classified variables for education, income, political parties, religion, and region, and open questions for occupation, nationality, and language, which are coded according to pre-classified country-comparable classifications.
• Trial interviews are conducted, and interviewers are thoroughly trained before going into the field.
• Quality control checks are carried out and documented on a sample of respondents, refusals, and non-contacts.

Methodological Guidelines designed by the EVS advisory groups for all EVS member countries.