A new dataset covering key demographic information from five major European survey programmes has been added to the NextGen Harmonised Data Gateway, developed as part of the Infra4NextGen project.

The new dataset brings together information on sex, age, education, employment status, place of living (urban/rural), legal partnership status and religious affiliation from five major cross-national survey programmes:

• Eurobarometer

• European Quality of Life Survey (EQLS)

• European Social Survey (ESS)

• European Values Study (EVS)

• International Social Survey Programme (ISSP)

The dataset complements the five thematic datasets published in February 2026, which cover the five pillars of the NextGenerationEU recovery plan: Green, Strong, Equal, Digital and Healthy.

But what is harmonised data?

When researchers want to compare data from different surveys, they often encounter a problem: even when two surveys collect information about the same topic, they may do so in different ways.

For example, one survey might ask respondents about their employment status using the categories "employed", "unemployed" and "inactive", while another might distinguish between full-time employment, part-time employment, unemployment, retirement and other categories.

Although both surveys collect information about employment, their results cannot necessarily be compared directly.

Data harmonisation addresses this problem by making information from different sources more consistent and comparable.

As part of the harmonisation process, researchers identify equivalent variables across surveys and standardise how their responses are coded and organised. This includes aligning response categories, numerical scales and how missing information is recorded.

The result is a dataset that makes it easier for researchers to combine and compare information from different surveys, without having to carry out all these adjustments themselves.

What does the new dataset mean for researchers?

The new demographics dataset provides a common set of background variables for respondents included in the five thematic harmonised datasets published earlier this year.

This allows researchers to examine how factors such as age, education or employment status relate to attitudes and behaviours across the five NextGenerationEU themes.

For example, a researcher interested in the green transition could investigate how attitudes towards environmental policies differ between age groups or levels of education, using harmonised data from several European survey programmes.

The new dataset also includes demographic information from participants in CRONOS-3, the self-completion panel survey conducted as part of Infra4NextGen. Attitudinal and behavioural data from CRONOS-3 will be incorporated into the second version of the five thematic datasets.

A syntax file is included with the download to help researchers merge the demographic information with the existing thematic datasets.

Accessing the harmonised data

All datasets are available through the NextGen Harmonised Data Gateway, which provides access to three main resources:

• Variable Database: Explore the variables used in the harmonisation process.

• Harmonisation Toolbox: Access resources and tools for understanding and carrying out data harmonisation.

• Data: Download the harmonised datasets for further analysis.

Researchers interested in learning more about the process can also access the free interactive online course Data Harmonisation.

The NextGen Harmonised Data Gateway was developed by a team of researchers led by Dr Insa Bechert at GESIS – Leibniz Institute for the Social Sciences.

For more information about the new dataset, visit the demographics dataset documentation or contact the data harmonisation team.