I am trying to compare the forecast accuracy of a number of methods using MAPE across different commodity markets, such as corn, wheat, soybeans, coffee, cotton. Obviously the relative MAPE’s area impacted by the relative volatilities of each commodity: a high MAPE for wheat may simply reflect a volatile market, not necessarily a poor forecast.
I am wondering how to correct for this: some kind of vol-adjusted MAPE I suppose, but I cannot find any literature on this. Alternatively, I was thinking of comparing the MAPE of a certain forecast method with the MAPE of a naïve forecast…this should also correct for the vol difference somewhat, I suppose.
Any further suggestions/comments are greatly appreciated.