I'm sure there is some kind of formula being used to arrive at the numbers, but I doubt it is a serious formula.
Interesting too, that the courses are mostly in order by their "score", but there are a few which are not ranked correctly ... in fact, there are a handful (Merion and Royal Melbourne included) which had a higher "score" than the #1 ranked course ... but they wouldn't have made anyone notice.
And, even though it's not serious, I will bet anyone who wants to take the action $100 that within a year I can find an advertisement or another article which mentions that Carne, Fancourt, or Poipu Bay were ranked in the top 20 courses in the world.