When I see them I'll ask them. They told me at the time but I've long since spaced it. I remember it had to do with being considerably less rigorous than usually required to make a causality claim. Here is a link one of the guys steered me to. He works for a health insurance company so he keeps a VERY low profile on this issue
http://www.davehitt.com/facts/index.html

We all like to think of ourselves as rugged individualists. But when push comes to shove most of us are sheep who do what we are told. Worst of all, a lot of us become unpaid agents of whoever is controlling the agenda by enforcing the current dogma on the few rugged individualists who actually exist.