There is a common perception that the prices of unrelated commodities move together. This paper re-examines this notion, using a measure of comovement of economic time series called concordance. Concordance measures the proportion of time that the prices of two commodities are concurrently in...

Univariate studies of the hypothesis of unit roots in real exchange rates have yielded consensus point estimates of the half-life of deviations from purchasing power parity of between three to five years. However, least squares-based estimates of half-lives are biased downward. Accordingly, we...

This paper examines the duration and magnitude of commodity-price cycles. It finds that for most 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 rebound in a subsequent boom. There is little evidence of a...

Consensus estimates put the half-life of deviations from purchasing power parity (PPP) at about four years (Rogoff, 1996). However, conventional least squares estimates of half-lives are biased downward. Accordingly, as a preferred measure of the persistence of real exchange rate shocks, this...