meet these objectives, the REF assesses institutions in terms of (1) research output, (2) societal impact of the research, and (3) the environment supporting the research. Here, we are concerned only with the assessment of research output. In the REF 2014, the assessment of research output accounted for $65\%$ of the overall assessment of institutions. Each output evaluated in the REF 2014 was awarded a certain number of stars: four stars indicates world-leading research, three stars indicates internationally excellent research, two stars indicates internationally recognised research, and one star indicates nationally recognised research.

The three above-stated objectives are each addressed in a different way. The overall *proportion* of high-quality research that has been produced is relevant for the first objective. Indeed, the REF 2014 website boasts that $30\%$ of the submitted UK research was world-leading four-star research: public investment results in high-quality science. The *proportion* of research outputs awarded a certain number of stars also provides a reputational yardstick for institutions and thereby serves the second objective. Indicators based on these proportions feature in various league tables constructed by news outlets such as the Guardian and Times Higher Education. Such indicators may influence the choice of students and researchers regarding 