World University Rankings created by Times Higher Education takes into account the reputation of research done by universities and how often papers produced by universities were quoted around the world.
Academic Ranking of World Universities offered by Shanghai Jiao Tong University focuses on the number of award-winning scientists, most cited researchers from the listed universities, and their contribution to the scientific community.
QS Rankings created by TopUniversities.com surveys a large number of academic experts about the reputation of universities and also measures the quality of teaching.
Best Global Universities Rankings created by USNews.com analyses university graduation rates and how many students remain enrolled in their second year of studies. It also surveys university representatives on the performance of universities.