Methodological Bias in the Clarivate Highly Cited Researchers List: International Comparisons and the Case of Portugal

The annual list of Highly Cited Researchers (HCR), published by Clarivate Analytics, is widely used as an indicator of scientific excellence and institutional prestige. However, growing evidence suggests that the methodology underlying this ranking contains significant structural limitations that may distort the measurement of research influence. This paper critically examines the methodological foundations of the HCR list and evaluates their implications for international comparisons of scientific performance. Using Portugal as an illustrative case study, the analysis reveals substantial inconsistencies when HCR results are compared with those obtained from the Stanford Scientists Ranking. Evidence from the scientometric literature—together with empirical comparisons involving Nobel laureates—suggests that the HCR list may systematically misrepresent scientific influence across countries and disciplines. The findings indicate that, unless substantial methodological reforms are implemented, the HCR list will continue to distort assessments of scientific excellence and may influence global university rankings that rely on it as a key indicator.