What factors lead to a search result showing up on page 1 or page 5 of Google?
What about the popularity bar in iTunes? How does it work?
Who decides what your salary is compared to the person down the hall?
On this road, in this town, what's the threshold before you'll get a speeding ticket?
In that magazine article, what's the methodology for ranking these semi-famous people?
How did this image show up in recommended?
There are ratings and rankings that ostensibly exist to give us information (and we are supposed to use that information to change our behavior).
But if we don't know what variables matter, how is it supposed to be useful?
Just because it can be easily measured with two digits doesn't mean that it's accurate, important or useful.
[Marketers learned a long time ago that people love rankings and daily specials. The best way to boost sales is to put something in a little box on the menu, and, when in doubt, rank things. And sometimes people even make up the rankings.]