[giantg2]

I work for a large company. There are four ratings you can be assigned - 'not doing your job', 'need more improvement', 'you're doing your job average to well', and 'exceptional' for about 8% of people.

I can't really tell you how it's measured or anything like that. The company has policies about it, but more often than not those policies are blatantly violated. It basically comes down to the subjective opinions of your manager, the department head, and the business people you interact with.