Why is St Andrews ranked so differently in rankings?Watch this thread
If anyone's curious about why St A does well in UK league tables for things like Physics, but not in the world league tables, it's because UK table emphasise things to do with undergraduate teaching more, and world ones emphasise things to do with research citations and research grants. St Andrews is so tiny that it struggles to rank highly in those areas.
The length of time it took me to find this post I'd've been quicker just retyping it...
So basically the tables that only rank UK unis use NSS (how happy are students with the teaching etc at the uni), number of staff per students, how much they spend on facilities, and how they did in the UK's research rating thing (REF). The worldwide league tables are based hugely on these "reputation surveys" of university staff and employers, which are a sort of vicious circle because if a league table tells you X is the best in the world, then next year if you're an academic or employer and you're asked "who's the best in the world" you're more likely to say the ones that did well last year...so it's basically a perception ranking rather than an actual experience-based ranking like the UK-only ones.