Research assessments tell us what and who did research impact, but say little about the why and how.

The introduction of impact into the 2014 Research Excellence Framework (REF) and the results it provided had a transformative effect on perceptions and approaches to research impact. However, REF 2021 and the results of the first KEF have had a more subdued reception. Vincent W Mitchell argues a reason for this is a lack of focus on tacit knowledge in both exercises, which whilst good at mapping out what universities and researchers do, are poor at providing analyses of how research impact could be improved.