Mean normalized covariance matrix, Corr, as a function of for the three lowest values of . The top figures are for Δr_⊥ = 0, with the righthand panel showing only points with Corr_AB< 0.1. The bottom two figures are for Δr_⊥ = 4 h^-1 Mpc (left) and Δr_⊥ = 8 h^-1 Mpc (right). Shown are the correlations given by the sub-sampling, by the sum of all the diagram expansion, and by the shuffle of forests. The shuffle technique fails for (Δr_⊥> 0,Δr_∥< 30 h^-1 Mpc) where inter-forest correlations dominate.