Bibliometric measurement of research performance and Price's theory of differences among the sciences

A severe criticism against the use of citation indicators for the measurement of a research group's performance holds that these indicators reflect at least partly the size of the scientific activity in the subfield or topic in which the group works. In this contribution an attempt is made to substantiate this claim within the framework of Price's theory on the processes of knowledge growth. Empirical evidence is presented that among a number of subfields from the natural and life sciences significant differences exist with respect to Price's index, and that the citation scores of research groups tend to be high in subfields showing a high value of Price's index and other characteristics of reference patterns. These findings suggest that groups sharing an intellectual focus with other researchers tend to obtain higher citation scores than groups working more ‘on their own’.