Over the past few years, increasing efforts have been made to evaluate research output using different markers of quality.1 This is most clearly reflected by the work of the Research Exercise Framework, a huge undertaking that was completed in 2014 and ranked subject areas in all UK universities according to the societal impact of research and the environment in which it was conducted, alongside the quality of research publications and other outputs. Still, in this Framework, 65% of the weighting was towards outputs and the approach used was a variant of peer review in which contributions were read and discussed by panel members.2 ,3 In 2015, the amount of allocated funding will be made proportionate to a university's ‘research power’, which is calculated by multiplying a weighted average score of the aforementioned quality criteria by the total number of full-time equivalent staff members working there.2 Similar considerations also apply to universities and individual researchers in relation to grant-funding, appointment and promotion.

A key determinant in most of these decisions is the impact factor of the journal in which research is published. Journal impact factors have historically been the preserve of one organisation, Thomas Reuters (formerly the Institute of Scientific Information or ISI), which publishes them every June or July in its Journal Citation Reports (JCR) for each journal that meets a basic set of rules, …