owg:
you said: "Taking the July 2004 value of 445.6 as an estimate of the index for 2004, we may be in for a 10% increase. Where did that come from?"
As commodities are world-priced in US$, then over the short run the value of the dollar index (DX) can be seen as an important driver of of the materials-component of prices. The Dollar Index goes down, and prices go up. Beyond that of course, since prices are set at the margin, China is an important (and growing) contributor to global GNP so thereby one could see this as useful data to consider.
I happen to live in a causeless choiceless world (yet that is quite another story LOL) and tend to see everything as already in the price of the index. "what is, is" ... so to speak.
However my analytical sense is, looking from an economics "causal" point of view - and if the data were available - a useful study would be to see how global GNP, US bond prices, and DX would be related to the CEPCI. I have not analyzed these, however.
Peace
Silverbaron