figuring out potency...how do i?

I was just wondering how i figure out the potency in the cooked/baked foods. I've seen in clubs, for example, a brownie labled 3X (3Xdosage), and the same sized brownie, made by the same person have a lable saying 9x. How is this figured? Can someone help a girl out? Thanks in advance.

It depends on the amount of flower,hash or keef used in the mix be cafull THC is processed through your liver so that means you will get 3X higher when consumed than smoking