Results of the spectral fit to simulated data with uncertainties derived from the E2E simulated maps. Distinct symbols and colours represent the different sky regions (see top row). The dashed lines in plots of β_s and β_d are the input values of our sky model. We retrieve these input values without any bias. The sky model has a non-zero correlation between dust and synchrotron polarization at low ℓ, which is consistent with the value of ρ found by fitting the simulated data.