This paper examines the duration and magnitude of cycles in commodity prices. We find that for the majority of commodities, price slumps last longer than price booms. How far prices fall in a slump is found to be slightly larger than how far they tend to rebound in a subsequent boom. We also find little evidence of a consistent `shape' to cycles in commodity prices. For all commodities, the probability of an end to a slump in prices is independent of the time already spent in the slump, and for most commodities, the probability of an end to a boom in prices is independent of the time already spent in the boom.
Cashin, Paul, John McDermott and Alasdair Scott (2002). ‘Booms and slumps in world commodity prices’, Journal of Development Economics, Elsevier, Volume 69(1), Pages 277-296, DOI: https://doi.org/10.1016/S0304-3878(02)00062-7.