Fig. 27.

Effect of profiling on the relative uncertainties of the valence up-quark distribution $\mathit{\delta }x{u}_{\mathrm{v}}(x)/x{u}_{\mathrm{v}}(x)$ (left) and the valence down-quark distribution $\mathit{\delta }x{d}_{\mathrm{v}}(x)/x{d}_{\mathrm{v}}(x)$ (right) as a function of Bjorken-x at a scale of $Q^2=1.9{\text{GeV}}^2$. The top row shows the MMHT14 PDF set and the bottom row shows the CT14 PDF set