"It is obvious that China will climb up university rankings in the years to come."This statement from Phil Baty, editor of the Times Higher Education World University Rankings, lines up with China's optimism that it will produce world-class universities. But there are still difficulties to overcome, experts say. Universities from China's mainland slipped in the 2011-2012 Times' global rankings. Peking University dropped 12 places from last year to 49th, and Tsinghua University fell to 71st place. Among Asian universities, Peking is ranked No. 4 and Tsinghua No. 8. A combination of factors determines rankings -- research output, study environment, reputation and international outlook. Due to China's economic development, investment   in education and research has increased, but the quality of education and research in Chinese academia seems not to have kept pace. The gauge   is the number of papers published in highly respected English-language journals, so while many papers are being produced in China, it appears not all are good enough to attract international attention. Still, higher education in China is developing quickly, thanks in part to huge government investment. China spent an amount equal to 3.69 percent of GDP on education last year, according to Ministry of Finance data. China has the largest and one of the fastest growing higher education systems in the world -- 2,723 schools for 31 million students. Enrollment   has increased more than four times from 2001 to 2011. All the following are factors that determine a university's ranking EXCEPT   _  .
the quantity of its published papers how good its study environment is the number of its graduates how well-known it is