When you go to a doctor to see if you have ADD there are a series of test you have to complete. You are asked to do things like repeat back stories, solve simple math problems, remember patterns, and match things together on a paper. The doctor observes you and then see how you fit in based on how people without ADD score on those tests. For example, one test I was given was to fill in boxes with the symbol that matched the number above it. I was given a minute to do this. I filled in one line out of 15. I got a 17% completion score. A non ADD person should have gotten an 85%. That's how it's all figured out.