I can't comment on exactly how rigorous the census part of it is. It does ask that one question about our tillage practices, but I wouldn't consider that all that rigorous.
The science behind measuring, seeing how, and interviewing the farmer has been on the same site for those 20 years. They go back to the same spot in those fields to measure it. There is a spot the farmer doesn't even know about, a little piece of metal a foot in the ground they can find, and they go back there repeatedly every five years. The next one coming up will be this coming fall, I think.