Traditional autocorrelation and variance ratio tests are based on serial uncorrelatedness rather than martingale difference. As such, they do not capture potential nonlinearity-in-mean, which could lead to misleading inferences in favor of the martingale hypothesis. This paper employs various...

In this paper we examine dynamic relationships among wheat prices from five countries for the years 1981-1999. Error correction models and directed acyclic graphs are employed with observational data to sort-out the dynamic causal relationships among prices from major wheat producing regions:...