ΛCDM best-fit C_ls along with C_ls plotted for two values of w, close to our ﹩99.7 \% ﹩ CL values. In the lower panel, the standard cosmological parameters are held at the ΛCDM best-fit values when w is varied, and in the upper panel they are varied in order to mask the effect of w. All curves as well as the Planck data points and their error bars have been transformed by ﹩{C}_{{\ell }}\to {C}_{{\ell }}+10({C}_{{\ell }}^{{\rm{\Lambda }}\mathrm{CDM}}-{C}_{{\ell }})﹩, effectively enlarging the residuals by 10 and shifting the mean values accordingly, to make them more visible. Comparison of the upper and lower plots shows how the degeneracies that w has with the standard cosmological parameters act to limit the constraints on w.