“…There have been intensive studies, either qualitative (Aguillo, Bar-Ilan et al, 2010;Angelis, Bassiliades, & Manolopoulos, 2019;Chen & Liao, 2012;Moed, 2017) or quantitative (Anowar, Helal et al, 2015;Çakır et al, 2015;Robinson-García, Torres-Salinas et al, 2014;Selten, Neylon et al, 2019;Vernon et al, 2018), on the comparisons of university rankings. Nevertheless, we wish to emphasize that the techniques required for a comprehensive understanding of this question are nontrivial.…”