What do global university rankings really measure? The search for the X factor and the X entity

Most academic rankings attempt to measure the quality of university education and research. However, previous studies that examine the most influential rankings conclude that the variables they use could be an epiphenomenon of an X factor that has little to do with quality. The aim of this study is to investigate the existence of this hidden factor or profile in the two most influential global university rankings in the world: the Academic Ranking of World Universities (ARWU) of the University of Shanghai Jiao Tong, and the Times Higher Education (THE) ranking. Results support the existence of an underlying entity profile, characterized by institutions normally from the US that enjoy a high reputation. Results also support the idea that rankings lack the capacity to assess university quality in all its complexity, and two strategies are suggested in relation to the vicious circle created between institutional reputation and rankings.