Ratios of power spectra for Planck and WMAP over the joint Planck/KQ75+Planck point source mask with f_sky = 56.7%. The Planck 70/100 and 143/100 ratios can be compared to the bottom middle panel in Fig. 6 for f_sky = 59.6%. Here we limit the horizontal scale because the WMAP noise beyond ℓ = 400 makes the ratios uninformative. The general shape of the Planck ratios is the same; however, it is clear (as it was in Fig. 6) that changes in the sky fraction change the ratios significantly within the uncertainties. This underscores the importance of strict equality of all factors in such comparisons.