How could you establish a base to compare 2 unique entities to...

How could you establish a base to compare 2 unique entities to apply an kind of apples for apples discount.

I don't think baseless.. i think it would be an estimate between two similar companies and a snapshot in time. I have used a ratio based on market cap between two similar companies to work out the WA premium / Africa Discount: EG BGS (46m) compared to KDR (460m). (1:10) and say eg: would you rather have 9 BGS's or 1 KDR? (or Africa Discount).

I'd love to see the formula for a generic application - but for now, estimates are convincing enough that the discount is well and truly alive and kicking on the ASX.. even with ballpark back of paper calculations its extremely compelling (and possibly that 90% is an accurate ballpark for January 2019 Lithium stocks - but if it's not apples and apples bear in mind the differences may be rather impactful)