[nick_dm]

I've heard that even at top universities in China there are trends among the subjects that don't really exist at the likes of Cambridge, MIT and Stanford.

For example it might be that CS is currently more popular than maths/ physics/engineering, as a result all most top students (including high scorers in the math or physics olympiads) will apply for CS at university regardless of their interest in the subject. Those with the very best performance on the entrance exams will be accepted for CS at Peking and Tsinghau, the next tier of students would have a choice between math/physics/eng. there or CS at a 2nd tier university, and other students between math/physics/eng. at a 2nd tier university or CS at a 3rd tier university.

On top of that the popular subjects will shift with time, so not only is it hard to judge a student's motivation but you might think that on paper someone is a good student because they were accepted for CS, but perhaps at that time CS was picking up students rejected from engineering.