The REF was a process of expert review. Institutions were invited to make submissions in 36 units of assessment (UOAs). The submissions were assessed by an expert sub-panel for each UOA, working under the guidance of four main panels.
The main panels oversaw the assessment, ensuring the assessment criteria and standards were consistently applied. They were responsible for signing-off the results recommended by the sub-panels. The main panels included international members to provide assurance about the international benchmarking of standards.
The sub-panels reviewed submissions according to a set of assessment criteria and level definitions. All sub-panels included research users that participated in the assessment of impact. Specialist advisers assisted with outputs in languages that the sub-panels were unable to assess.
The main and sub-panels carried out the assessment according to the published 'Panel criteria and working methods'. At the end of the assessment, each main panel and its sub-panels produced an overview report detailing how they operationalised the criteria, and providing general observations about the assessment and the state of research in their discipline areas.
The members of the REF panels were appointed by the four UK funding bodies. The process used for appointing them is detailed in 'Units of assessment and recruitment of expert panels'.