Frequency-averaged TE (left) and EE (right) spectra, not corrected for T-to-P leakage (see text). The theoretical TE and EE spectra plotted in the upper panels are computed from the best-fit model of Fig. 11. Residuals with respect to this theoretical model are shown in the lower panels. The error bars show ±1σ uncertainties. The green lines in the lower panels show the best-fit temperature-to-polarization leakage model, fitted separately to the TE and EE spectra. From Planck Collaboration XIII (2016).