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Closer - The home of longitudinal research

Harmonised data sources

Individual studies

Individual longitudinal population studies may provide harmonised data directly to researchers at the point of download.

See whether the study or studies you are interested in have already generated harmonised data relevant to your research question by checking their available data on their website or where the data is stored (e.g. the UK Data Service). If harmonised data is available, it is normally outlined in the dataset description or documentation.

This could be data harmonised across the separate waves or sweeps of data collection in that study, so the data can be compared over time. For example:

  • The main data files for Understanding Society include the harmonised data from 18 waves of the British Household Panel Survey (BHPS), the study which preceded Understanding Society: The UK Household Longitudinal Study

Alternatively, the files could contain the study data in a format that can be easily harmonised with other data. For example:

  • The data from a sub-study of the English Longitudinal Study of Ageing (ELSA) called the Harmonised Cognitive Assessment Protocol (HCAP) is available in a format that is harmonised with other HCAP studies, so it can be easily merged and compared to these other data sources.

Other data sources

There are also projects and organisations that generate and hold harmonised data from multiple longitudinal population or other types of studies. Harmonised data or derivation code is sometimes provided for download directly from these organisations, or guidance is given on where the harmonised data can be accessed.

Explore some of these harmonised data sources below: