<p>I believe that is just one of the “methodologies” used. That website describes the methodology as:
"Subject area rankings are solely based on the results from an academic peer review survey. Early in that survey process, respondents are asked to identify their broad faculty area of knowledge from five areas: arts and humanities; engineering and IT; life sciences and biomedicine; natural and physical sciences; and social sciences. Academics then rate schools in the subject area or areas where they have broad knowledge. Respondents are able to nominate more than one faculty area, and the total therefore adds up to more than 100 percent. Those five subject area ratings are then compiled to produce the separate rankings in each of the subject areas.’ and so on for a few paragraphs. </p>
<p>I am not sure what that all means but it seems to be a lot more than “citations per paper”.</p>
<p>The above is the only subject ranking I have ever seen. 000ace00, do you know of any others?</p>