For the calculation of Citations per Faculty, Citations per Paper, Paper per Faculty, H Index and International Research Network indicator, QS gathers two distinct datasets: paper count over a five-year period and citations count for six years for papers published over a five-year period.
We collect data on research publications and citations from our partners at Elsevier Scopus. An extract is provided to us in Q1 of each year which is used for the new cycle of each ranking, beginning with the World University Ranking. You can read more on Elsevier's page at Elsevier Scopus and Rankings
Adjustments
We apply the following significant adjustments to the papers and citations we index.
1. Affiliation Cap.
The cap is variable and calculated individually for each QS subject, ensuring no more than 0.1% (0.001) of research is excluded in a given field. Affiliation caps screen out papers with more than a given number of Scopus Affiliation IDs from the bibliometric analysis either overall or in the given subject only (see attached document in the bottom of this article for more details).
For example, in Agriculture (AGR01), we may exclude all papers with more than 20 co-authoring institutions resulting in 1140 papers and accounting for 0.1% of that subject overall. This may differ from Anthropology (ANT01) where the affiliation cap is only 11 co-authoring institutions and only 62 papers, but results in the same 0.1% exclusion rule.
Please find the link to the current affiliation caps by subject in the bottom of this page. This year it represented around 1.41% of the database and prevents highly cited material produced by very large research groups conferring too much credit on institutions who have only contributed in very small part to the work. Whilst often high-profile and important research, these papers cause distortion for a university that may not be especially research-active otherwise.
2. Paper-type exclusions. See here.
3. Self-citations exclusion. We use an author-level definition of self-citations, as opposed to a journal-level or institution-level definition (https://www.elsevier.com/research-intelligence/resource-library/research-metrics-guidebook).
4. Faculty Area Normalization (only in QS World University Rankings and QS University Rankings by Region). Due to publishing patterns and practices, a straight ratio of citations per faculty, citations per paper or papers to faculty places a strong emphasis on life sciences and medicine, as well as on natural sciences. In consultation with our advisory board and sector, QS has opted to adopt a model which aims to broadly equalize the influence of research in our five key faculty areas. A more detailed technical explanation of how this works can be found here. Classification of papers into faculty areas is based on Elsevier's ASJC codes (see 'ASJC Mapping' section here).
Please refer to our QS Scopus User Guide for help in interpreting the various research counts provided for institutions.