Frequently Asked Questions

About the ESS


To achieve the breadth of coverage required, the ESS uses a combination of repeated key items (the core section) and rotating modules. The core allows change and continuity across a wide range of social variables to be monitored. The inclusion of rotating modules increases the scope of the survey as they focus on a specific topic in depth.

In addition to the core and rotating sections of the questionnaire, a third section contains (1) the well-established 21-item measure of human values developed by the Israeli psychologist Professor Shalom Schwartz and is used to classify respondents according to their basic value orientations, and (2) a number of repeat measures from the main questionnaire asked in a slightly modified form, using the Multi-Trait Multi-Method (MTMM) approach to evaluate the reliability and validity of the items, in an effort to measure and improve the quality of the questions fielded.

Until ESS Round 7, the 21-item human values scale and experimental tests used to be part of the supplementary questionnaire, which is now incorporated in the main questionnaire.

Two question module design teams (QDTs) are selected following an open call for proposals for multinational teams of leading academics in Europe. Applicants can choose to design a new module, i.e. which has never been featured in the ESS before, or offer to repeat an existing rotating module, choosing to maintain some or all of the items.

The selected QDTs work closely with the Core Scientific Team (CST) to develop the theoretical underpinning of the module and the items used to measure each complex concept and determine how these can be used in analysis. The development of the rotating modules is documented in the Questionnaire Design Templates available on the website.

The ESS questionnaire is currently designed to last no longer than 55 minutes when administered in British English, including the supplementary questionnaire and excluding optional country-specific questions, the interviewer questions, and general administration of the contact procedures.

The topics covered at least once by the ESS since its inception include media and social trust, politics, subjective well-being, gender, household, socio demographics, human values, immigration, citizen involvement, health and care, economic morality, family, work and well-being, timing of life, personal and social well-being, welfare attitudes, ageism, trust in justice, democracy, health inequalities, climate change and energy use, justice and fairness, and digital social contacts.

The ESS develops a source questionnaire in British English, but considers both cross-cultural and translation implications within its design.

Once the source questionnaire is finalised, each participating country must translate it into all first languages that apply to 5% or more of their population. This is to ensure that the questionnaire is available in as many languages as is practical.

To limit the number of errors which might occur during translation, the process must include Translation, Review, Adjudication, Pretesting and Documentation (TRAPD) procedures.

For more details on how the ESS questionnaire is translated, please visit the Translation page.

Up until Round 10 (2020-22), the ESS was administered in-person by trained interviewers, using a standardised interviewing approach (where interviewers are trained to ask questions exactly as they are written), and the interview usually took place in the respondent’s home. The use of computer-assisted personal interviewing (CAPI) has been required since Round 9.

Due to measures implemented to help prevent the spread of Coronavirus, some countries fielded our Round 10 questionnaire using self-completion methods for the first time. As a result of the inclusion of data that was collected using only self-completion modes, we published a short briefing: Notes on ESS Round 10 data release

For more information on the data collection mode used by each country in a specific ESS Round, please consult the relevant Data Documentation Report available in the ESS Data Portal.

To ensure that the ESS data can be used to make inferences about the general population and to minimise the margin of error, each country must achieve a minimum effective sample size of 1500 (after discounting for design effects). For smaller countries (those with a population of less than 2 million), this number is reduced to 800. Taking these factors into account, countries must decide how many participants they will select from their sampling frame, i.e. their gross sample size, and predict how many completed interviews they will need to achieve (their net sample) in order to meet their effective sample size.

For more details on the ESS methodology, please visit the Methodology section.

The ESS fieldwork period lasts at least six weeks within a five-month period (usually the period from September of the survey year to January of the following year) in each country. The National Coordinator (NC) is responsible for the national implementation of fieldwork, the monitoring of fieldwork and the deliverables. The Survey Agency conducts the fieldwork according to the ESS specifications, provides information on the progress of fieldwork to make monitoring by the NC and the Core Scientific Team (CST) possible, and plays a supporting role in the preparation of deliverables.

For more information on the fieldwork in each country, please consult the Data Documentation Report for the relevant round in the ESS Data Portal.

The ESS selects new sample members each round (cross-sectional sampling). To ensure comparability, all countries must use random probability sampling. This means that everyone (aged 15 and over, resident within private households) must have a chance to be selected, and that their chances of selection are known. Once selected, an individual cannot be replaced by anyone else, even if they cannot be contacted, are ill or refuse to take part.

For more details on the ESS methodology, please visit the Methodology section.


ESS data is usually released for the first time in October of the year after fieldwork takes place (e.g. October 2019 for ESS Round 9). A second release usually happens in May of the following year, and additional releases are scheduled as needed.

For each round, the ESS makes available several data sets: an integrated file including data from all countries participating in that round, interviewer’s questionnaire data, test variables data, contact forms data, media claims data. Round-specific themes or data protection reasons might also result in additional data sets being made available for selected variables.

For more details on the available ESS data, please visit the ESS Data Portal.

The ESS data is available free of charge for non-commercial use and can be downloaded from the ESS DataPortal after a short registration.

The data is available either as a country-specific file or in an integrated international dataset, which includes data from all countries for a particular round.

For more details on how to cite ESS data and documentation, please visit the Data access section of the relevant round in the ESS Data Portal.

Users who wish to make use of the time series data are also able to build their own cumulative dataset, choosing to download all variables across all countries for all rounds or tailoring the dataset for their own needs.

Users who wish to analyse the ESS data with reference to the context they live in are able to do so by adding data on countries and regions (4 different levels) to the ESS data.

Sources for contextual data may include Eurostat, OECD, UN, UNESCO, World Bank, Freedom House, WHO, Transparency International, IMF, Bertelsmann Stiftung, CIRI Human Rights Project, Democracy Barometer, The Comparative Political Data Sets and Database of Political Institutions.

If you want to merge data (combine variables for the same respondents) from different files of the same ESS round, you have to use the variables CNTRY (Country) and IDNO (Respondent’s identification number) as merging (“by”/”key”) variables, in that order. All files that you download from this website are sorted by CNTRY and IDNO.

If you prefer to use question numbers rather than ESS variable names, you can download a correspondence table for renaming variables.

ESS1 (2002): XLS

ESS2 (2004): XLS

ESS3 (2006): XLS

ESS4 (2008): XLS

ESS5 (2010): XLS

ESS6 (2012): XLS

ESS7 (2014): XLS

ESS8 (2016): XLS

ESS9 (2018): XLS

ESS10 (2020): XLS (F2F) | XLS (SC)

For other data formats or subsets, please visit the ESS Data Portal.

From ESS9 on, sampling variables (e.g. on clustering and stratification) are included in the main dataset.

For ESS Rounds 1 to 6, the SDDF is available for download as a country-specific file from the ESS Data Portal. Starting with ESS Round 7, an integrated version of the SDDF including all countries is available for download from the relevant Round data page.

In the SDDF, the clustering variable is PSU and the stratification variable is STRATIFY. As applies to other ESS data files (see How do I combine data files? above), the SDDF can be merged with the main dataset using the variables CNTRY (Country) and IDNO (Respondent’s identification number).