the cynical1,
Ambrian worked out the enterprise value of each AIM-listed producer and explorer (ie Mkt Cap + debt - cash, etc).
For each producer they divided the Ev by annual production oz - hence gained a figure for value/oz assigned by the market at that time.
They then calculated the average/oz for all producers - it came out at £2k/oz.
They repeated the same process for all non-producers on AIM (based on their reported Jorc M.I.I. resources) and therefore produced an average value/oz assigned by the market.
It is admittedly a very rough guide to estimation of what a company may be worth. I take it as a starting point for deeper investigation. It tends to highlight those companies at a large discount or premium to their peers and hence worthy of closer investigation as to reasons (political/country risk, management, costs, minelife, metallurgy, environmental, et al).
Chip