The three longest established and most influential global rankings are those produced by Quacquarelli Symonds (QS), Times Higher Education (THE) and ShanghaiRanking Consultancy (the Academic Ranking of World Universities; ARWU). All of these, along with other global rankings, primarily measure the research performance of universities rather than their teaching. They have been criticised for being "largely based on what can be measured rather than what is necessarily relevant and important to the university", and the validity of the data available globally has been questioned.