Methodology: Citations per faculty
Citations, evaluated in some fashion to take into account the size of institution, are the best understood and most widely accepted measure of research strength. Often calculated on a "per paper" basis, the THE - QS World University Rankings has adopted a "per faculty member" approach since its inception in 2004. The Citations per Faculty score contributes 20% to the overall rankings score.
For the calculation of this indicator, QS gathers two distinct datasets:
Total citation count for the last five years
There are three major sources of pubication and citation data worldwide, these are the Web of Science from Thomson Reuters; Scopus from Elsevier and Google Scholar. In the first three years of the THE - QS World University Rankings, results from the Essential Science Indicators (ESI), a subset of the Web of Science were used. In 2007, the switch was made to Scopus for a number of reasons, but principally due to broader journal coverage leading to results for a larger number of institutions.
Full Time Equivalent (FTE) faculty
Faculty numbers used are totals... whilst it would be ideal to separate the notions of teaching and research and use the former for calculating the Student Faculty Ratio and the latter for this indicator, it has not been possible to do so as data to that degree of distinction has so far proved unavailable for many countries in the study. The definition of exactly what data we request has evolved gradually over the years to minimize ambiguity.
2008 citation counts are based on a version of Scopus dated 23rd June
Scopus is a rapidly evolving system, data included in the THE - QS export may differ significantly from the current content of Scopus online.
Many commentators have suggested that, given the accepted validity of citations, this measure should carry a significantly higher weighting than it does. Ultimately, however, this places extremely strong emphasis both on medical and life sciences and on intitutions from countries where the principal medium of instruction is English.
Whilst it has its critics, the Academic Peer Review places equal emphasis on Arts and Social Sciences as it does on Natural and Life Sciences. This is its great strength and, above all, the reason why it carries such a high weighting.
At time of writing, Scopus is working to add more books to its index, which ought to help in less scientific fields ad QS and Times Higher Education continue to seek alternative measures to evaluate outputs from lower citing disciplines.