I think the research by Casey is good except I'm not so sure of the conclusions.

The supply / demand argument has been used for a long time for gold but supply/demand applies to commodities. Since gold is not "consumed" and above supplies can come back at any time, it is an interesting vehicle to value.

In addition, reserves have been decreasing due to gold price and gold companies high-grading. The first reason is due to accounting measures that the gold companies cannot use uneconomic ore to count for their reserves. If gold were to rise and settle comfortably at higher levels, we could magically see gold companies re-catorgorize uneconomic ore as "reserves".

Bottom line, I'd rather focus on when economies and currencies go south which will make gold rise in a more substantial and convincing manner than supply/demand.