(a) Scatter plot χ² versus innermost slope ω of the fits for the three potentials resulting from the MCMC navigation of the posterior. The large times symbols represent the best fit obtained with unconstrained f(ϵ), which yield unphysical f(ϵ) < 0. The vertical gray line marks ω = −0.01. (b) Histograms of the distribution of innermost slopes for the points in (a). (c) Histograms of χ² for the points in (a). The arrows represent the χ² of the best fit obtained with unconstrained f(ϵ). Panels a, b, and c share the same color code as indicated in the insets.