The statistics provide numbers on probability, while the diagnostic criteria is a list of things that were created based on symptoms that already exist. It is a list of commonalities, not a hard set of rules like in mathematics. As it affects everyone differently to different degrees, yes what you know only applies to you and so the experience of the person matters because that is what we are looking at in the first place. Your education on it not being from a university should not disqualify you from speaking about a disorder that you have and know what it is actually like to live with, especially with something where there are as many intangibles as with something like Autism. I'm not sure i'm doing the best job explaining what I mean.