Change points (if any) in years and results of the BDS test for the commodity time series.

BDS tests the null hypothesis that the standardized residuals of the change point model come from a stationary stochastically independent process. A low P value rejects the hypothesis of stationary independence. ‘Inference’ is our interpretation of the statistics. Change point model fits, GARCH fits, and results of bootstrapped BDS P values are presented in Supplementary Information.