Eurofound survey methodology

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Each of Eurofound’s pan-European surveys targets a different population to gather high-quality information on living conditions, working conditions and workplace practices.

Despite the differences target population, Eurofound aims to harmonise survey methodology whenever possible, to ensure that lessons learned in one survey are implemented in the others.

As with all research projects, both Eurofound stakeholders and experts in the relevant field are involved in the development, implementation and evaluation of each survey edition, ensuring their relevance for European and national-level policymakers and social partners.

Validity and reliability

By involving experts in the questionnaire development, and also national-level experts in the translation process, Eurofound aims to ensure that all survey questions capture the real-world phenomena they are intended to capture.

It is also important to ensure the consistency of survey measurements. Eurofound does so by carefully selecting representative samples, choosing the most suitable mode of administering the questionnaires using state-of-the-art technology, recruiting experienced interviewers and providing comprehensive training for interviewing and coding, as well as through minute checking of the collected data, sophisticated weighting and appropriate analysis.

Eurofound’s commitment to producing high-quality information is further shown in its quality assurance strategy for surveys.

Sampling

Regardless of whether individuals, workers or establishments are the target population of a survey, it is not feasible to collect information from all members of that population. Therefore, a sample of respondents is chosen to be as representative as possible of the total population.

Eurofound aims to use sampling frames of the highest possible quality. In each country, it tries to find a register which covers at least 95% of the target population. For the ECS, it is preferable that these registers contain the contact information for establishments, otherwise company registers are used. For the EWCS and the EQLS, the registers usually contain address information of households or individuals. When no such register is available, Eurofound uses a so-called ‘random route’ procedure to generate a list of possible respondents.

Eurofound also aims to draw samples that are large enough to give valid results on the level of individual countries and that reflect the distribution of the European population well enough to enable generalisations to Europe as a whole.

The first aim requires that the sample size on a country level is at least 1000 respondents, reducing the margin of error to an acceptable level. The second aim is the reason for selecting bigger samples in bigger countries, as done in the most recent EWCS and EQLS.

Coding

Sometimes it is necessary to ask open-ended questions, which are not directly answerable by a pre-determined set of responses. This may be the case for sector, for example. The interviewer will first note the given answer in all detail and later on assign it to the appropriate category in the Europe-wide statistical classification of economic activities (NACE).

Coding will typically have to be applied for open-ended questions related to income, the respondents’ educational level (via ISCED), as well as the region they are living in (via NUTS).

Weighting

Once the fieldwork phase is completed, the datasets are weighted to compensate for various possible causes of imbalance in the sample. The fact that different people have a different probability of being selected for the survey has to be taken into account statistically. The bigger the unit (household/company) people are living or working in, the smaller their chances of being interviewed. Also, variations in the level of willingness to participate in a survey may result in the underrepresentation of certain respondent groups. The differences in the size of the workforce in the various countries are not (fully) reflected in the national sample sizes. Therefore, weighting ensures that larger countries weigh heavier in the EU-level results.

The European Labour Force Survey (LFS) is frequently used as a source of reference data for judging the extent to which the data are representative of the population.

Eurofound adapts the methodology to the specific requirements of each survey. More information is available on the individual survey pages.