Survey Organization

Mid-Life in the United States (MIDUS)

Midlife in the United States (MIDUS) is a national longitudinal study of health and well-being. It was conceived by a multidisciplinary team of scholars interested in understanding aging as an integrated bio-psycho-social process. Since its inception in 1995 MIDUS has continued to grow, such that it now includes data from over 10,000 individuals, comprising thousands of variables in different scientific areas among distinct cohorts.

LISS (Longitudinal Internet studies in the Social Sciences)

This online panel survey, administered by CentERdata, a research institute located in Tilburg in the Netherlands, documents its data using DDI 3 through a backend called Questasy.

General Social Survey

The General Social Survey (GSS) is one of NORC's flagship surveys and its longest running project. Begun in 1972, the GSS and has been monitoring social change and the growing complexity of American society.

Gallup Europe

Gallup serves the European Union by providing public opinion tracking in the candidate region. Authorized users can access and download the full data files of all publicly available Candidate Countries Eurobarometer surveys Gallup has carried out in the past four years through the Nesstar interface.

European Social Survey (ESS)

The European Social Survey (ESS) is an academically driven cross-national survey that has been conducted every two years across Europe since 2001. The survey measures the attitudes, beliefs and behaviour patterns of diverse populations in more than thirty nations.ESS data are provided in the Nesstar online analysis system.


A key part of the CLOSER project is the creation of a Uniform Search Platform allowing users to search the metadata from all of the projects included to find key variables for their research. The metadata will be substantially enhanced and made available in DDI-Lifecycle format.