Fig. 3
From: Determining the chaotic behaviour of copper prices in the long-term using annual price data
ln 'divergence' vs. time plot. a Analysis of τ = 1. All m values are appropriate. b Analysis of τ = 2. m = 5 and m = 5 are doubtful. m = 3, 4, and 7 are appropriate. c Analysis of τ = 3. All combinations are rejected
