What exactly are NADA guides?

Question

Where does NADA get any of their information, because they are way off from Edmunds.com and seem to let dealers charge way more than they need to.

Answer 1

Edmond's in my opinion is more of a pro-consumer site as opposed to NADA which bases their numbers on past transactions of actual sales. NADA's values are recognized by many lending institutions.

Answer 2

NADA gathers statistics and reports based on the average list price for dealers.  This may be the reason they "let dealers charge way more than they need to".

Dealers usually will be willing well below the retail price for any given car.