Best-fit β_f and Δ_f from 5% perturbed Z_p. Left: 2D histogram (contours, log10, spacing 0.5, spanning three orders of magnitude) of best-fit β-Δ-values from 100 000 perturbed data sets. We note that the 2D histogram shows two peak values (indicated by cyan dots), none of them co-located with the unperturbed (β = 1/3,Δ = 2/3) pair (red dot). Right: underestimation of Z₅ favors Δ_f = 1. Shown is, for a subset of 1000 perturbed data sets, Δ_f as function of , again for an unperturbed pair (β = 1/3,Δ = 2/3). Colors indicate .