Proxy strengths may vary

Phil Baty (World University Rankings column, 19 August) tells us that citations data are "widely accepted as a strong proxy for research quality" and they "will have a high weighting" in the Times Higher Education World University Rankings 2010. Yet I cannot remember a single instance where your weekly Thomson Reuters table has given us rankings by citation in non-science subjects such as art history, Classics or philosophy.

It seems a mistake to give a high weighting to a measure that may be widely accepted only in some, but far from all, subjects. Even if different weightings were employed for different subjects to reflect this fact, another proxy might be a better alternative in these cases. Will THE reconsider using citations data in all subjects? If not, then I will expect a future "Top Institutions" table on the top universities in art history or philosophy.

Thom Brooks, Editor, Journal of Moral Philosophy, University of Newcastle.