Using ISI's 'Highly Cited Researchers' to obtain a country level indicator of citation excellence

A high level of citation to an author's work is, in general, a testimony to the fact that the author's work has been noted and used by his peers. High citation is seen to be correlated with other forms of recognition and rewards, and is a key indicator of research performance, among other bibliometric indicators. The Institute for Scientific Information (ISI) defines a 'highly cited researcher' (HCR) as one of 250 most cited authors of journal papers in any discipline. Citation data for 20 years (1981-1999) is used to calculate the share of HCRs for countries in 21 subject areas. We find that the US dominates in all subject areas (US share similar to 40-90%). Based on the number of highly cited researchers in a country, an index of citation excellence is proposed. We find that rank order of countries based on this index is in conformity with our general understanding of research excellence, whereas the more frequently used indicator, citations per paper, gave an unacceptable rank order due to an inherent bias toward very small countries. Additionally, a high value of the index of citation excellence was found to be associated with higher concentration of highly cited researchers in affiliating organizations.